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Unit 1 (Botany) B Sc 2nd Semester Ecology, Ecological Factors and Plant Communities Introduction to Ecology: The two components of the nature, organisms and their environment are not only much complex and dynamic but also interdependent, mutually reactive and interrelated. Ecology, relatively a new science, deals with the various principles which govern such relationships between organisms and their environment. The term ecology was coined by combining two Greek words, oikos (meaning house or dwelling place) and logos (meaning the study of) to denote such relationships between the organisms and their environment. Thus, literally ecology is the study of organisms at home. There is some controversy about the author who coined the term ecology and first included it in the literature , but there is consensus that the German biologist, Ernst Haeckel first gave substance to this term, Ernst Haeckel gave definition and substance to the term, which he first used in 1866, in the following statement written in 1870: ‘By ecology we mean the body of knowledge concerning the economy of nature the investigation of the total relations of the animal both to its inorganic and to its organic environment; including above all, its friendly and inimical relation with those animals the plants with which it comes directly or indirectly into contact-in a word’. Ecology is the study of all the complex interrelations referred to by Darwin as the conditions of the struggle for existence. More recently Kerbs (1985) has defined ecology as the scientific study of the interactions that determine the distribution and abundance of organisms. Soil origin, composition and formation Soil profile Soil: Soil is the surface layer of land. Soil is not a single factor but it is a complex of several soil factors, which together constitute the soil complex. With the exception of parasites and epiphytes all plants are dependent directly on the soil for mechanical anchorage, minerals and water supply. Type of land plants and animals are determined by grain size, porosity, pH and mineral composition of the soil. The principle components of the soil are the minerals and water which are responsible for the distribution of the plants. Formation (origin) of soil The process of soil formation is generally divided into two stages: a) Weathering and b) Soil development or Pedogenesis. a) Weathering: Breakdown of bigger rocks into fine, smaller mineral particles is known as weathering. The weathering processes are physical, chemical. (i). Physical weathering: Physical processes may be of following types. 1. Wetting-Drying: It is the disruption of layer lattice minerals which swell on wetting. 2. Heating-Cooling: It is disruption of heterogenous crystalline rocks in which inclusions have differential coefficients of thermal expansion. It occurs particularly in dry climates, where due to sun heating large boulders flake at surfaces. 3. Freezing: This is the disruption of porous, lamellar or vesicular rocks by frost shatter due to expansion of water during freezing. 4. Glaciation: Larger masses of snow and ice glaciers, while falling may cause physical erosion of rocks through grinding process. Page 2 of 22

5. Solution: Some more mobile components of rocks, such as calcium chlorides, sulphates etc., are simply removed by agents like water 6. Sand blast: In arid, desert conditions the rocks are disrupted by physical action of wind sand etc. (ii). Chemical weathering: Chemical processes include the following. 1. Hydration: As a result of taking water, due to reversible changes of haematite to limonite

(Fe2O3 ← Fe2O3H2O), the rock swell. This swelling causes the disruption of sandstones etc. 2. Hydrolysis: In this process, components like alumino-silicates of rock breakdown during which elements such as potassium and surplus silicon are washed out which give rise to simpler mineral matter like clay alumino-silicates. For example, hydrolysis of orthoclase to kaolinite. 3. Oxidation-Reduction: Some oxidation-reduction chemical reactions such as reversible change of Fe3+ to Fe2+ cause disruption of rocks because Fe2+is more soluble than Fe3+. 4. Carbonation: Some chemicals produced in the atmosphere and those during the metabolism of microorganisms bring about carbonation. As for example reversible change of CaCO3 to Ca(HCO3)2 leads to solution loss of limestone or disruption of CaCo3 cemented rocks as the hydrogen carbonate is more soluble than the carbonate. 5. Chelation: Some chemical exudates, produced through biochemical activity of microorganisms like lichens, Bacteria etc., are able to dissolve out mineral components of the rocks. these metals dissolved with organic products of microbial activity are known as chelates. For example, acids produced by lichens and bacteria have strong chelating properties. b) Pedogenesis: During weathering, the rocks are broken down into smaller particles. But this is not true soil and plants cannot grow in this matter. The weathered material undergoes further a number of changes which is a complex process, known as pedogenesis or soil development. It is a complete biological phenomenon. During this phenomenon, living organisms such as lichens, molluscs, bacteria, fungi, algae, microarthropods etc; as a result of secretion of organic acids, enzymes, CO2 production and addition of organic matter after their death, bring about geochemical, biochemical and biophysical processes. Due to all this, the crusts of weathered rock debris are converted to true soils consisting of complex mineral matrix in association with a variety of organic compounds, and a rich microorganism population. Composition of soil (Basic soil components): A soil is simply a porous medium consisting of minerals, water, gases, organic matter, and microorganisms. The traditional definition is: Soil is a dynamic natural body having properties derived from the combined effects of climate and biotic activities, as modified by topography, acting on parent materials over time. There are five basic components of soil that, when present in the proper amounts, are the backbone of all terrestrial plant ecosystems. 1. Mineral: The largest component of soil is the mineral portion, which makes up approximately 45% to 49% of the volume. Soil minerals are derived from two principal mineral types. Primary minerals, such as those found in sand and silt, are those soil materials that are similar to the parent material from which they formed. They are often round or irregular in shape. Secondary minerals, on the other hand, result from the weathering of the primary minerals, which releases important ions and forms more stable mineral forms such as silicate clay. Clays have a large surface area, which is important for soil chemistry and water-holding capacity. Additionally, negative and neutral charges found around soil minerals influences the soil's ability to retain important nutrients, such as cations, contributing to a soils cation exchange capacity (CEC). Page 3 of 22

The texture of a soil is based on the percentage of sand, silt, and clay e.g. if a soil contains 20% clay, 40% sand, and 40% silt then it is a loam. The identification of sand, silt, and clay is made on the basis of their size. Sand: 0.05 – 2.00 mm in diameter Silt: .002 - 0.05 mm in diameter Clay < 0.002 mm in diameter

2. Water: Water is the second basic component of soil. Water can make up approximately 2% to 50% of the soil volume. Water is important for transporting nutrients to growing plants and soil organisms and for facilitating both biological and chemical decomposition. Soil water availability is the capacity of a particular soil to hold water that is available for plant use. The capacity of a soil to hold water is largely dependent on soil texture. The smaller particles in soils, the more water the soil can retain. Thus, clay soils having the greatest water holding capacity and sands the least. Additionally, organic matter also influences the water holding capacity of soils because of organic matter's high affinity for water. When water is bound so tightly to soil particles, it is not available for most plants to extract, which limits the amount of water available for plant use. Although clay can hold the most water of all soil textures, very fine micropores on clay surfaces hold water so tightly that plants have great difficulty extracting all of it. Thus, loams and silt loams are considered some of the most productive soil textures because they hold large quantities of water that is available for plants to use. 3. Organic matter: Organic matter is the next basic component that is found in soils at levels of approximately 1% to 5%. Organic matter is derived from dead plants and animals and as such has a high capacity to hold onto and/or provide the essential elements and water for plant growth. The percentage of decomposed organic matter in or on soils is often used as an indicator of a productive and fertile soil. Over time, however, prolonged decomposition of organic materials can lead it to become unavailable for plant use, creating what are known as recalcitrant carbon stores in soils. 4. Gases: Gases or air is the next basic component of soil. Because air can occupy the same spaces as water, it can make up approximately 2% to 50% of the soil volume. Oxygen is essential for root and microbe respiration, which helps support plant growth. Carbon dioxide and nitrogen also are important for below ground plant functions such as for nitrogen-fixing bacteria. If soils remain waterlogged (where gas is displaced by excess water), it can prevent root gas exchange leading to plant death, which is a common concern after floods. 5. Microorganisms: Microorganisms are the final basic element of soils, and they are found in the soil in very high numbers but make up much less than 1% of the soil volume. A common estimate is that one thimble full of topsoil may hold more than 20,000 microbial organisms. The largest of these organisms are earthworms and nematodes and the smallest are bacteria, actinomycetes, algae, and fungi. Microorganisms are the primary decomposers of raw organic matter. Decomposers consume organic matter, water, and air to recycle raw organic matter into humus, which is rich in readily available plant nutrients. Other specialized microorganisms such as nitrogen-fixing bacteria have symbiotic relationships with plants that allow plants to extract this essential nutrient. Such "nitrogen fixing" plants are a major source of soil nitrogen and are essential for soil development over time. Mycorrhizae are fungal complexes that form mutualistic relationships with plant roots. The fungus grows into a plant's root, where the plant provides the fungus with sugar and, in return, the fungus provides the plant root with water and access to nutrients in the soil through its intricate web of hyphae spread throughout the soil matrix. Without microbes, a soil is essentially dead and can be limited in supporting plant growth. Page 4 of 22

Soil profile:

The soil profile is defined as a vertical section of the soil that is exposed by a soil pit. A soil pit is a hole that is dug from the surface of the soil to the underlying bedrock. The soil profile is an important tool in nutrient management. By examining a soil profile, we can gain valuable insight into soil fertility. Components of the Soil Profile: A soil horizon makes up a distinct layer of soil. The horizon runs roughly parallel to the soil surface and has different properties and characteristics than the adjacent layers above and below. The soil profile is a vertical section of the soil that depicts all of its horizons. The soil profile extends from the soil surface to the parent rock material. Master Horizons: There are 5 master horizons in the soil profile. Not all soil profiles contain all 5 horizons; and so, soil profiles differ from one location to another. The 5 master horizons are represented by the letters: O, A, E, B, and C. O: The O horizon is a surface horizon that is comprised of organic material at various stages of decomposition. It is most prominent in forested areas where there is the accumulation of debris fallen from trees. A: The A horizon is a surface horizon that largely consists of minerals (sand, silt, and clay) and with appreciable amounts of organic matter. This horizon is predominantly the surface layer of many soils in grasslands and agricultural lands. E: The E horizon is a subsurface horizon that has been heavily leached. Leaching is the process in which soluble nutrients are lost from the soil due to precipitation or irrigation. The horizon is typically light in colour. It is generally found beneath the O horizon. B: The B horizon is a subsurface horizon that has accumulated from the layer(s) above. It is a site of deposition of certain minerals that have leached from the layer(s) above. C: The C horizon is a subsurface horizon. It is the least weathered horizon. Also known as the saprolite, it is unconsolidated, loose parent material. Physiochemical properties of Soil : (texture and pH):

Soil texture: it refers to the size of soil particles and is of great importance to vegetation because it determines the water holding capacity and soil aeration of particular region it also determines the availability of water for absorption to some extent. Soil pH: it determines the type of soil micro-organisms, solubility of different minerals and type of plants which grow. In alkaline soils (pH above 7) there is reduced availability of Zn, Mn, and Fe. In acidic soils there is abundance of Fe, Mn and Al but deficiency of Ca, Mg and K. availability of minerals is optimum in neutral soils. Plants grow best in neutral and slightly acidic soils. Slight acidity of soil favours forest formation while slight alkalinity promotes formation of grasslands. Different crop plants require different pH. Certain soils possess excess of salts especially those of Na and Mg, they are called saline soils. Salinity increases with excessive irrigation. Saline soils are virtually barren because very few plants grow in such soils. Another type of infertile soil is alkali soil. Page 5 of 22

Water- States of water in environment: Water is a transparent, tasteless, odourless and colourless. Water is the main constituent of Earth's streams, lakes, and oceans, and the fluids of most living organisms. Water covers 71% of the Earth's surface. It is vital for all known forms of life. On Earth, 96.5% of the planet's crust water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapour, clouds (formed of ice and liquid water suspended in air), and precipitation. Only 2.5% of this water is freshwater, and 98.8% of that water is in ice (excepting ice in clouds) and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater (0.003%) is contained within biological bodies and manufactured products. A greater quantity of water is found in the earth's interior. States of water: 1. Solid Water: Ice is frozen water. When water freezes, its molecules move farther apart, making ice less dense than water. This means that ice will be lighter than the same volume of water, and so ice will float in water. Water freezes at 0o Celsius, 32oFahrenheir. 2. Liquid water: is wet and fluid. This is the form of water with which we are most familiar We use liquid water in many ways including washing and drinking. 3. Water as Gas: Vapor is always present in the air around us. You cannot see it, when you boil water, it changes from a liquid to a gas or water vapour. As some of the water vapour cools, we see it as a small cloud called steam. This cloud of steam is a minivesion of the clouds we see in the sky. At sea level, steam is formed at 100o Celsius, 212o Fahrenheit The water vapor attaches to small bits of dust in the air. It forms rain drops in warm temperatures. It freezes and forms snow or hail.

Precipitation: Precipitation is the process by which all forms of water reach back to earth from the atmosphere

Forms of Precipitation:

1. Rain: Rain is the form of precipitation that is in the form of water drops of a size larger than 0.5mm. Rain fall is the predominant form of precipitation Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the earth. It provides suitable conditions for many types of ecosystems, as well as water for hydroelectric power plants and crop irrigation. 2. Snow: Snow consists of ice crystals in a flaky from (Average density 0.1 g/cc). The process of precipitating snow is called snowfall. 3. Drizzle: Drizzle is a light liquid precipitation consisting of liquid water drops smaller than those of rain – generally smaller than 0.5 mm in diameter. Precipitation rates from drizzle are on the order of a millimetre per day or less at the ground. Owing to the small size of drizzle drops, under many circumstances drizzle largely evaporates before reaching the surface and so may be undetected by observers on the ground. 4. Glaze (Freezing rain): The glaze is formed when the rain or drizzle comes in contact with the cold ground at around 0-degree Celsius. The water drops freeze to form an ice coating. 5. Sleet: Sleet is frozen raindrops formed when rainfall passes through the air at subfreezing temperatures. Page 6 of 22

6. Hail: Hail is the type of showery precipitation in the form of pellets or lumps of size greater than 8mm. Hail occurs in violent thunderstorms. Types of precipitation: Precipitation occurs when the moist air mass undergoes condensation. This process happens when the air is cooled and saturated with the same amount of moisture. This process of cooling air mass is performed only when the air mass moves up to higher altitudes. The air mass can be lifted to higher altitudes mainly by three methods based on which there are three types of precipitation namely 1. Cyclonic Precipitation 2. Convective Precipitation 3. Orographic Precipitation 1. Cyclonic Precipitation: It is caused by the lifting of air mass due to pressure difference. A cyclone is a large low-pressure region with circular wind motion. There are two types of cyclones. a). Frontal precipitation: A frontal is called as the hot moist air mass boundary. This precipitation is caused by the expansion of air near the frontal surface. b). Non-Frontal precipitation: This is a cold moist air mass boundary that moves and results in precipitation. 2. Convective Precipitation: The air above the land area gets heated up by some causes. The warmer air rises up and cools and precipitates. It is showery in nature. This type of precipitation happens in varying intensities. The areal extent of convective precipitation is small in range of less than 10 km in diameter. 3. Orographic Precipitation: Moving air masses have chances to strike barriers like mountains. Once they strike, they rise up which cause condensation and precipitation. The precipitation is greater in the windward side of the barrier compared to the leeward side of the barrier. Effect of Light on Plants: Light plays an important role in the species composition and development of vegetation. Light is abundantly received on the surface of the earth. And, on an average approximately only 2-3 per cent of this solar energy is used in Primary Productivity. Light intensity shows special variations due to the factors like atmospheric water layer, particles dispersed in the air, etc. Further, the vegetation of an area may also affect the light intensity. In deep shade under trees, or under water, light becomes limiting below which photo-synthesis is not sufficient for effective growth. Light plays a vital role directly or indirectly in regulating the growth (structure, form, size), metabolism, development and distribution of plants. The plants are influenced by light in the following ways: 1. Effect on Chlorophyll synthesis: The synthesis of chlorophyll in green plants can take place only in the presence of light. It is seen that if a coprophilous plant is kept in prolonged darkness, the chlorophyll amount practically disappears. 2. Effect on number and Position of Chloroplasts: Light has marked effect on the number and position of chloroplasts, the chlorophyll bearing organelle. The upper surface of leaves which receive maximum sunlight has the largest number of chloroplasts arranged in line with the direction of light. On the other hand, the leaves of the plants which shade chloroplasts are very few in number and arranged at right angles to the light rays, thus increasing the surface of absorption. 3. Effect on Photosynthesis: Photosynthesis is a process of conversion of solar energy (light) into chemical energy (in presence of chlorophyll) which is subsequently used for the preparation of carbohydrate from carbon dioxide and water. Page 7 of 22

4. Effect on Respiration: In plants, respiration is a process of the oxidation of carbohydrate (produced in the photosynthesis) into carbon-dioxide and water. According to Calvin (1958), the rate of respiration increases at higher light intensity and it decreases at lower light intensity. 5. Effect on Transpiration: The rise in atmospheric temperature which may be due to the conversion of solar radiation into heat increases the rate of transpiration. The process of opening of stomata (which depends upon light) leading to loss of water from the aerial surface of plants is known as transpiration. 6. Effect on Production of Hormone: Light inhibits the synthesis of auxins or growth hormones in plants as a result of which the shape and size of the plants gets modified. 7. Effect on development of Flowers, Fruits and Vegetative parts: The intensity of light largely influences the growth and development of flowers, fruits and vegetative parts of plants. Light of higher intensity favours development of flowers, fruits and seeds but light of lower intensity promotes the development of vegetative parts and causes delicacy. 8. Effect on Formation of Anthocyanin Pigment: Intense light helps in the formation of anthocyanin pigments in plants. The plants in Alpine regions have beautiful flowers containing this pigment. 9. Effect on Movement: The effect on sunlight in modulating the movement of plants is called phototropism or heliotropism. The elongation of stem towards light is known as positive photo- tropism and the movement of roots away from light is known as negative photo-tropism. The leaves grow transversely to light. 10. Effect on Photoperiodism: The response of plants to the relative length of the day (known as photo-period) is known as photoperiodism. According to the response of the plants to the length of the photo-period, the plants have been classified into three groups: i). Long Day Plants (L.D.P.): The plants which bloom when the light duration is more than 12 hours per day e.g. radish, potato, spinach, etc. ii). Short Day Plants (S.D.P.): The plants which bloom when the light duration is lesser than 12 hours per day e.g. cereals, tobacco, cosmos, dahlia etc. iii). Day neutral Plants (D.KP.): The plants which show little response to the length of the day light e.g. cotton, balsam, tomato, etc. 11. Effect on Seed Germination: The germination of seeds is largely influenced by light. In most of the plants, the red light induces seed germination and, in some plants, blue light promotes the process. In some cases, far-red light is seen to inhibit seed germination. 12. Effect on Distribution of Plants: The duration and intensity of light plays an important role in determining the distribution of plants. Hence the vegetation of different geographical regions is different from one another. 13. Effect on Photo-morphogenesis: The development of plants in seedling stage is controlled by light. The seedlings present in dark condition are non-green and highly elongated with poorly developed root system and no-foliage. However, an exposure of the dark grown seedling to light makes it normal. Effect of Temperature on Plants:

Temperature is one of the essential and obvious changeable environmental factors. It varies not only between climatic regions, but also in the temporal changes of all habitats. It is one of the most extensively studied environmental factors. It penetrates into every region of the biosphere and profoundly influences all forms of life by exerting its action through increasing and decreasing some of the vital activities of plants also. Temperature has a universal influence and acts as a limiting factor for the growth and distribution of plants. The interaction of temperature with certain other abiotic Page 8 of 22 environmental factors such as humidity, air, etc., cause into many other climatic changes which influence the plants in one way or another. 1. Effect on Growth: When the temperature is slightly increased, the seedlings of several plants exhibit the elongation of the hypocotyl. Excessively low temperatures can also cause limiting effects on plant growth and development. For example, water absorption is inhibited when the soil temperature is low because water is more viscous at low temperatures and less mobile, and the protoplasm is less permeable. At temperatures below the freezing point of water, there is change in the form of water from liquid to solid. The expansion of water as it solidifies in living cells causes the rupture of the cell walls. 2. Effect on Transpiration: Transpiration is the process of loss of water from the aerial surface of plants. The rate of transpiration increases with increase in atmospheric temperature and vice versa. 3. Effect on metabolism: All metabolic processes are influenced by temperature since temperature regulates the activities of enzymes. All chemical reactions in the body of plants are controlled by temperature. It affects the rate of transpiration, photosynthesis and respiration in plants. It also affects seed germination. 4. Effect on reproduction: Flowering in plants is affected by temperature through thermoperiodism i.e., the response of plant to rhythmic diurnal fluctuations in temperature. Temperature is an important factor in the phenology of plants. (study of periodical phenomena of plants, as the time of flowering in relation to climate).

Ecological adaptation in Hydrophytes: Hydrophytes may differ from each other in some aspects, but most of the characteristic, morphological and as well as anatomical, are common to all of them. The features of these plants which enable them to become adopted to such hydrophytic conditions. Hydrophytes shows three levels of Ecological Adaptations, they are: (1). Morphological adaptations: (Adaptations in external features) (2). Anatomical adaptations (Adaptations in internal features) (3). Physiological adaptations (Adaptations in metabolic features) 1). Morphological Modifications: I). Roots: Roots in hydrophytes are meaningless as body which is in direct contact with water acts as absorptive surface and absorbs water and minerals. This may probably be the reason why roots in hydrophytes are reduced or absent. i). Roots may be entirely absent in as in Wolfia, Salvinia and Ceratophyllum or poorly developed as in Hydrilla, . In Salvinia submerged leaves compensate for roots. However in emergent forms, as Ranunculus which grow in mud roots are well developed with distinct root caps ii). Root hairs are absent or poorly developed iii). Root caps are usually absent. In some cases as Eichhornia root caps are replaced by root pockets. iv). Roots, if present are generally fibrous adventitious , reduced in length , unbranched or poorly branched. In Lemna roots act simply as balancing and anchoring organs. v). In some plants, as Jussiaea, there develop some floating aerial roots also in addition to normal adventitious roots. Page 9 of 22

Figure 2 Wolfia Figure 3 Hydrilla Figure 4 Eichornia Figure 1 Jussiaea II). Stem: i). In aquatic Submerged plants e.g. Hydrilla and Potomogeton stem is long slender, spongy and flexible. In free floating forms it maty be slender, floating horizontally on water surface as in Azola, or thick or short stoloniferous and spongy as in Eichornia. In forms which are rooted with floating leaves, it is a rhizome, as in Nymphaea and Nelumbo. ii). Vegetative propagation by runners, stolons, stem and root tubers, dormant apices, offsets etc., is most extensive and common method of reproduction. Thus, most of them are perennial.

III). Leaves: i). Leaves in submerged hydrophytes are thin, and are either long and ribbon shapes as in Vallisneria, or long and linear as in Figure 5 Nelumbo Potomogeton, or finely dissected as in Ceratophyllum. Floating leaves are large flat and entire as in Nymphaea and in Nelumbo with their upper surfaces coated with wax; Their petioles are long, flexible and often covered with mucilage. In Eichornia and Trapa petioles become swollen and spongy ii). Emergent forms as Ranunculus and Sagittaria show heterophylly with submerged floating and aerial leaves. iii). Submerged leaves are generally translucent.

Figure 1 Vallisneria Figure 2 Hydrilla Figure 3 Potamogeton Figure 4 Ranunculus

IV). Flowers and seeds: These are less common in submerged forms. Where flowers develop, seeds are rarely formed.

V) Pollination and dispersal of fruits and seeds are accomplished by the agency of water. Seeds and fruits are light in weight and thus they can easily float on the surface of water. Page 10 of 22

VI) Vegetative reproduction is common method of propagation in hydrophytes. It is accomplished either through fragmentation of ordinary shoots or by winter buds. In algae, reproduction is accomplished by zoospores and other specialized motile or non-motile spores.

2). Anatomical Modifications: Anatomically the hydrophytes shows the following characteristics and their anatomical adaptations ensure these features. I). Reduction in protecting structures: II). Increase in the aeration. III). Reduction of supporting or mechanical tissues IV). Reduction in vascular tissues I). Reduction in protecting structures: i). The cuticle is totally absent in submerged parts of hydrophytes. ii). In aerial parts, the cuticle may present as a very thin layer. iii). Epidermis is Not the protecting layer. iv). Epidermal cells contain chloroplasts. v). Epidermal cells can absorb water and nutrients. vi). Hypodermis poorly developed, cells are thin walled. II). Increase in the aeration i). Stomata is completely absent in submerged parts of hydrophytes. ii). Sometimes vestigial stomata present. iii). Exchange of gases in hydrophytes takes place through the cell wall. iv). In floating plants stomata confined to upper epidermis of the leaf. v). The aerenchyma is well developed in submerged plants. vi). Air chambers in the aerenchyma are filed with respiratory gases and moisture. III). Reduction of supporting or mechanical tissues i). Mechanical tissues are absent or poorly developed in hydrophytes. ii). Thick walled sclerenchymatous cells totally absent in hydrophytes iii). In Nymphaea, special type of star shaped lignified cells (asterosclereids) present which will provide mechanical support. iv). Main function of roots is to anchor in the soil (not the absorption of nutrients and water). IV). Reduction in the vascular tissues i). Vascular elements are poorly developed in hydrophytes. ii). Absorption of water and minerals takes place through the cell surface. Thus, very little importance is there for vascular tissues. iv). The xylem is highly reduced in the vascular bundles of hydrophytes. Usually, the xylem is represented by few tracheid’s only. vi). Sometimes the xylem not at all developed. vii). Phloem usually ill developed, sometimes well developed. viii). Vascular bundles are arranged towards the centre of the organ. Page 11 of 22

ix). Secondary growth totally absent.

3. Physiological Adaptations of Hydrophytes

i). Low osmotic concentration of cell sap in hydrophytes. ii). The osmotic concentration is equal or slightly higher to that of surrounding water. This prevents the unnecessary entry of water into the cells. iii). Water is absorbed by the entire plant surface. iv). Nutrients are absorbed by entire plant surface. v). Gaseous exchange takes place through the entire plant surface. vi). Both stem and leaves can do photosynthesis. vii). Oxygen produced by photosynthesis is retained in the air cavities. viii). This oxygen is utilized when required. Page 12 of 22

ix). Transpiration absent in submerged plants. Emerged plants and floating plants have excessive transpiration. x). Mucilage cells produce plenty of mucilage. xi). Mucilage prevents the decay of plants in the water. xii). Vegetative reproduction is the most common method of reproduction xiii). Pollination and dispersal of fruits in hydrophytes are facilitated by water

Ecological adaptations in Xerophytes The features which enable xerophytes to survive under the prevailing xeric conditions are as follows. 1. Morphological (external) adaptations; 2. Anatomical (internal) adaptations; 3. Physiological adaptations. 1). Morphological (external) adaptations: I). Roots: i). Root system is well developed in true xerophytes. ii). They are adapted to reach the area where water is available and to absorb water as much as possible”. iii). Roots will be profusely branched and more elaborate than their stem. iv). Most of the roots in xerophytes are perennial and they survive for many years. v). Roots grow deep into the soil and they can reach a very high depth in the soil. vi). Root surface is provided with dense root hairs for water and mineral absorption. II). Stem: i). Stem woody and hard in some xerophytic plants. ii). Stem usually green and photosynthetic. iii). Stem is covered with thick cuticle, wax and silica e.g. Equisetum. iv). In many plants, the stem is covered with dense hairs e.g. Calotropis v). Stem modified into thorns in Ulex. vi). Succulent and bulbous xerophytes can store water in their stem. Example: Cactus and some species of Euphorbia. vii). Stem may be modified into phylloclades, cladophylls or cladodes. Phylloclades: Stem modified into flattened leaf-like organs (Opuntia). Cladode: Many axillary branches become modified into small needle like green structures which look exactly like leaves (Asparagus). Cladophyll: branches developed in the axil of scale leaves, become metamorphosed to leaf- like structures (Ruscus). III). Leaves: i). Leaves usually absent in xerophytes. ii). If leaves are present, usually they are caducous (fall off easily). iii). Most of the cases the leaves are modified into spines or scales (Casuarina). v). Leaf may modify into phyllode in some plants. Phyllode: leaf petiole or rachis modified (flattened) into leaf like organ Example: Acacia. 2). Anatomical (internal) adaptations: I). Roots i). Root hairs are well developed in xerophytes. ii). Roots with well-developed root cap. Page 13 of 22

iii). In Asparagus, the roots become fleshy and store plenty of water. iv). In Calotropis, root cells are with very rigid cell wall. II). Stem i). In succulent xerophytes, the stem possesses water storing regions. ii). Epidermis is well developed and with thick walled compactly packed cells. iii). Cuticle is very thick and well developed over the epidermis. iv). Hypodermis is several layered; often hypodermis will be sclerenchyma (Casuarina). v). Stomata are present on the stem for gaseous exchange and transpiration. vi). Stomata are sunken type and usually situated in pits provided with hairs (Casuarina). vii). Vascular tissue is well developed with prominent xylem and phloem components. viii). In most of the xerophytes, the bark will be well developed and thick. ix). Many oil and resin canals are present in bark. x). Most of the cases, the stem will be photosynthetic and contains chlorenchymatous cells in the outer ex. xi). In the stem of Casuarina, the chlorenchymatous cells are radially elongated and palisade like tissue in appearance.

III). Leaf i). Epidermis of the leaf is thick and may be multi-layered, covered externally by thick cuticle. In some plants epidermal cells store water. In some monocots, some epidermal cells are larger than rest of the cells.called bulliform cells, which play role in leaf rolling to reduce transpiration. ii). Hypodermis usually present. In Pinus, the hypodermis is sclerenchymatous. iii). Mesophyll is well developed in xerophytic leaves. Many layered palisade tissues present. Spongy tissue is less developed in xerophytes with less intercellular spaces. ix). Leaves of Aloe have water storing region in the mesophyll. x). Stomata are reduced in numbers and are situated only on the lower sides of the leaves called hypostomatic leaves. Stomata are sunken type and usually situated in pits with hairs (Nerium). xi). Vascular tissue is well developed with plenty of xylem elements. xii). Mechanical tissue well developed in the leaves of xerophytes. xiii). Transfusion tissue, if present, will be well developed for the lateral conduction. 3. Physiological adaptations. i). Xerophytic plants are reported to contain pentosan polysaccharides which are reported to offer resistance against drought conditions. ii). Many xerophytes show CAM (Crassulacean Acid Metabolism) cycle. In these plants, the stomata remain closed during day time and open during the night and absorb enough carbon dioxide for the photosynthesis. Absorbed carbon dioxide is converted into malic acid and store in the vacuoles of the cells. The malic acid increases the osmotic concentration of cell sap and this enables the closure of stomata in the day time. iii). Some enzymes such as catalase and peroxidase amylase are more active in xerophytes. iv). They ensure the reduced rate of transpiration loss of water by thick cuticle, distribution of stomata in the lower side of the leaf, sunken type of stomata, and positioning of stomata in pits with many hairs. v). Xerophytes possess high osmotic concentration of cell sap. High osmotic concentration ensures the rapid and effective absorption of water. Thus, cells have high osmotic pressure. High osmotic pressure increases the turgidity of the cells. Due to this high turgor pressure, the wilting of cells is prevented by the extreme heat. vi). Tissue of succulents possesses mucilage to hold large amount of water. vii). Loss of high proportion of body mass with rapid recovery when water is available. Page 14 of 22

viii). Produce brightly coloured, large and showy flowers for attracting pollination agents. ix). Cactoid plants produce large amounts of minute seeds with thick seed coat for protection. Seed surface also possesses mucilage substances to absorb and hold water when it is available. x). Some plants quickly complete their life cycle before the unfavourable conditions.

Ulex stem Some succulent xerophytes

Phylloclades and cladodes Casuarina Pinus needles Plant communities characteristics: A plant community is a recognizable and complex assemblage of plant species which interact with each other as well as with the elements of their environment and is distinct from adjacent assemblages. A plant community is not a static entity, rather it may vary in appearance and species composition from location to location and also over time. What makes each of these communities distinguishable to us is its general physiognomy or physical structure. Characteristics Structure of plant communities can be determined by 1. Analytical characters 2. Synthetic characters. 1. Analytical characters: These are of two types (a) quantitative, which are expressed in quantitative terms, and (b) qualitative, which are expressed only in qualitative way. I). Quantitative characters: These include such characters as frequency, density, cover, basal area and abundance etc.

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i). Frequency: Frequency is the number of sampling units (as %) in which a particular species occurs. Thus, frequency of each species is calculated as follows:

Number of sampling units in which the species occurred Frequency (%) = ------X 100 Total no. of sampling units studied x 100 After determining the percentage frequency of each species, various species are distributed among Raunkiaer’s (1934) five frequency classes depending upon their frequency values as follows:

Frequency% Frequency class 0-20 A 21-40 B 41-60 C 61-80 D 81-100 E

ii). Density: Density represents the numerical strength of a species in the community. The number of individuals of the species in any unit area is its density. Density gives an idea of degree of competition. It is calculated as follows. Total no of individuals of the species in all the sampling units Density = ------Total no. of sampling units identified (iii). Cover and Basal area:

Cover: Cover is primarily the area of ground occupied by the above ground parts of the plant such as leaves stems and inflorescence as viewed from above It is estimated by chart quadrat or point quadrat method. It is a good measure of herbage availability Basal area refers to the ground actually penetrated by the stems and is readily seen when the leaves and stems are clipped at the ground surface. It is one of the chief characteristics to determine dominance. It is measured either 2.5 cm above the ground or actually on the ground level by callipers, line interception or point-centered quadrat method. (iv) Abundance: This is the number of individuals of any species per sampling unit of occurrence. It is calculated as follows— Total no. of individuals of the species in all the sampling units. Abundance = ------No. of sampling units in which the species occurred. II). Qualitative characters: These include physiognomy, phenology, stratification, abundance, sociability, vitality and vigour, life form (growth form), etc.

i). Physiognomy: This is the general appearance of vegetation as determined by the growth form of dominant species. For example, the community having trees and some shrubs as the dominants, it can be concluded that it is a forest. Page 16 of 22

ii). Phenology: Phenology is the calendar of events in the life history of the plant e.g. date and time of seed germination, vegetative growth, flowering and fruiting, leaf fall, seed and fruit dispersal, etc. iii) Stratification: Stratification of communities is the way in which plants of different species are arranged in different vertical layers in order to make full use of the available physical and physiological requirements. iv). Abundance: Plants are not found uniformly distributed in an area. They are found in smaller patches or groups, differing in number at each place. Abundance is divided in five arbitrary groups depending upon the number of plants. The groups are very rare, rare, common, frequent and very much frequent. v). Sociability: Sociability or gregariousness expresses the degree of association between species. Plants of some species grow better when nearer to each other others become weak and dry in such an association vi). Vitality: It is the capacity of normal growth and reproduction which are important for successful survival of species. In plants, stem height, root length, leaf area, leaf number, number and weight of flowers, fruits, seeds, etc., determine the vitality. vii). Life form (growth form): A life form is ―the sum of the adaptation of the plant to climate. On the basis of the position of perennating buds on plants and the degree of their protection during adverse conditions, Raunkiaer classified plants into five broad life-form categories which are as follows: a). Phanerophytes: Their buds are naked or covered with scale, and are situated high upon the plant. These life forms include trees, shrubs and climbers generally common in tropical climates. b). Chamaephytes: In these plants, the buds are situated close to the ground surface which gets protection from fallen leaves and snow cover. Chamaephytes commonly occur in high altitudes and latitudes, e.g., Trifolium repens. c). Hemicryptophytes: These are mostly found in cold temperate zone. Their buds are hidden under soil surface protected by the soil itself. Their shoots generally die each year. Examples-most of the biennial and perennial herbs. d). Cryptophytes or Geophytes: In these plants, the buds are completely hidden in the soil as bulbs and rhizomes. Cryptophytes include the hydrophytes (buds remaining under water), halophytes (marshy plants with rhizomes under the soil) and geophytes (terrestrial plants with underground rhizomes or tubers). e). Therophytes: These are seasonal plants, completing their life cycle in a single favourable season, and remain dormant throughout the rest unfavourable period of year in the form of seeds. They are commonly found in dry, hot or cold environment (deserts). 2. Synthetic characters: These are determined after computing the data on the quantitative and qualitative characters of the community. Synthetic characters are determined in terms of the following parameters: (i) Presence and Constance: It expresses the extent of occurrence of the individuals of a particular species in the community, i.e., how uniformly a species occurs in a number of stands of the same type of community. The species on the basis of its percentage frequency may belong to any of following five presence classes that were first proposed by Braun Blanquet. a). Rare—present in 1 to 20% of the sampling units. b). Seldom present—present in 21-40% of the sampling units. Page 17 of 22

c). Often present—present in 41-60% of the sampling units. d). Mostly present—present in 61-80% of the sampling units. e). Constantly present—present in 81-100% of the sampling units. (ii) Fidelity: Fidelity or ―Faithfulness‖ is the degree with which a species is restricted in distribution to one kind of community. Such species are sometimes known as indicators. The species have been grouped into five fidelity classes which were first formulated by Braun Blanquet: a). Fidelity 1: Plants appearing accidentally (Strangers) b). Fidelity 2: Indifferent plants may occur in any community (Indifferents). c). Fidelity 3: Species which occur in several kinds of communities but are predominant in one (Preferentials). d). Fidelity 4: Especially present in one community but may occasionally occur in other communities as well (Selective). e). Fidelity 5: Occur only in one particular community and not in others (Exclusives). iii). Dominance: It is used as a synthetic as well as analytical characters (Daubenmire, 1959). The number of organisms sometimes may not give correct idea of the species. If one bases his conclusion on number, a single or few trees in a grassland, or few grasses in a forest should be of little value. But if he considers the species on the basis of area occupied or biomass, the situation may be different. Thus, cover is included as an important character in dominance. Relative dominance (cover; RDO) is calculated as follows: Dominance (cover) of the species Relative Dominance (lover) = ------X 100 Total dominance (cover) of all the species (iii) Importance Value Index (IVI): This index is used to determine the overall importance of each species in the community structure. In calculating this index, the percentage values of the relative frequency, relative density and relative dominance are summed up together and this value is designated as IVI or importance value index of the species. It provides the idea of the sociological structure of a species in its totality in the community, but does not indicate its position separately with regard to other aspects. For IVI, values of relative density, relative frequency and relative dominance are obtained as follows: Density of species Relative density = ------X 100 Total density of all the species

Frequency of the species Relative frequency = ------X 100 Total Frequency of all the species

Dominance (cover) of the species Relative Dominance (lover) = ------X 100 Total dominance (cover) of all the species

Ecotone: Page 18 of 22

An ecotone is a transition area between two biomes. It is where two communities meet and integrate, for e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem. Other examples are grassland (between forest and desert), estuary (between fresh water and salt water) and river bank or marsh land (between dry and wet). It may be narrow (between grassland and forest) or wide (between forest and desert). As it is a zone of transition, it has conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension. Usually, the number and the population density of the species of an outgoing community decreases as we move away from community or ecosystem. A well-developed ecotone contains some organisms which are entirely different from that of the adjoining communities. Edge Effect: The edge effect is an ecological concept that describes how there is a greater diversity of life in the region where the edges two adjacent ecosystems overlap, such as land/water, or forest/grassland. At the edge of two overlapping ecosystems, you can find species from both of these ecosystems, as well as unique species that aren’t found in either ecosystem but are specially adapted to the conditions of the transition zone between the two edges. The organisms which occur primarily or most abundantly in this zone are known as edge species. In the terrestrial ecosystems edge effect is especially applicable to birds. For example, the density of birds is greater in the mixed habitat of the ecotone between the forest and the desert. Ecological or biotic succession : changes in a community succession:

The occurrence of relatively definite sequence of communities over a long time in the same area resulting in establishment of stable or climax community, is known as ecological or biotic succession. It is so because the biotic communities are never stable but dynamic, changing more or less regularly over period and space. These are never found permanently in complete balance with their component species or with the physical environment. Ecological succession is an orderly and evolutionary process of community development in a habitat. The first community to inhabit an area are called pioneer community while the last and stable community in an area is called climax community. The intermediate communities between the pioneer and climax communities are called transitional or seral communities. The entire series of communities is called sere.

Causes of Ecological Succession. These can be divided into two categories:

a). Biotic factors. The interactions among the organisms in a community are collectively called biotic factors. These influence the structure, composition and function of a community. In ecological succession, each community drives itself out of its habitat because it makes the area less favourable for itself and more favourable for the next seral community and so on. b). Physiographic factors. These include the physical and chemical factors of the environment which determine the nature and composition of a community. These include landslides, erosion, catastrophic factors, hails and storms, frost, fire etc. Basic types of succession. These are of following types: 1). Primary succession: In any of the basic environments (terrestrial, fresh water; marine), one type of succession is primary succession which starts from the primitive substratum where there was no previously any sort of living matter. For example land formed by volcanic lava or a newly formed estuarine mud bank or sand dunes or glaciated surface. Conditions at extreme so unfit for the growth of most plants and animals. The first group of plants establishing there are known as the Page 19 of 22 pioneers, primary community or primary colonisers. It takes longer period e.g. development of forest climax on a sand dune or barren land may take about 1,000 years. 2). Secondary succession: Another general type of succession is secondary succession which starts from previously built up substrate with already existing living matter. The action of any external force, as a sudden change in climatic factors, biotic intervention, fire etc. causes the existing community to disappear. Thus, area becomes devoid of living matter but its substratum. instead of primitive, is built up. It has organic matter so is biologically fertile. Such successions are comparatively more rapid. Biotic community undergoes several changes and ultimately gives rise to a climax community. Time taken is about 50-100 years in case of a grassland about 100-200 years for a forest. 3). Autogenic succession: After the succession has begun, in most of the cases, it is the vegetation itself which as a result of its reactions with the environment, modifies its own environment and thus causing its own replacement by new communities. This course of succession is known 35 autogenic succession. 4). Allogenic succession: In some cases, however, the replacement of the existing community is caused largely by any other external condition and not by the existing vegetation itself. Such a course is referred to as allogenic succession.

On the basis of successive changes in nutritional and energy contents, successions are sometimes classified as: 1). Autotrophic succession: It is characterized by early and continued dominance of autotrophic organisms like green plants. It begins in a predominantly inorganic environment and the energy flow is maintained indefinitely. There is gradual increase in the organic matter content supported by energy flow. 2). Heterotrophic succession: It is characterized by early dominance of heterotrophs, such as Bacteria, Actinomycetes, Fungi and Animals. It begins in a predominantly organic environment there is a progressive decline in the energy content. Depending mainly upon the nature of the environment (primarily based upon moisture relations) where the process has begun, and thus it may be a hydrosere or hydrarch-starting in regions where water is in plenty e.g. ponds, lakes, streams, swamp, etc. a mesarch-where adequate moisture conditions are present; and a xerosere or xerach-where moisture is - present in minimal amounts such as dry deserts, rocks etc. Sometimes, these are further distinguished: the lithosere initiating on rocks, psammosere-on sand and halosere-in saline water or soil. General process of ecological succession: The whole process of a primary autotrophic succession is actually completed through a number of sequential steps like: 1). Nudation. It involves the development of a bare area without any form of life. The cause of nudation may be topographic (e.g. soil erosion, landslide, volcanic eruption etc.) or climatic (cg. glaciers, hails, storms, fire etc.) or biotic (epidemics, human activities etc.) 2). Invasion. It involves successful establishment of a species in a bare area. It involves three steps: a). Migration (dispersal). It involves reaching of seed, spores. etc. in a bare area through the agencies like air, water etc. b). Ecesis (establishment). After migration of seeds, spores or propagules germinate, seedlings grow and adult start to reproduce. Some of the plants which acclimatise others perish. Page 20 of 22

c). Aggregation. It involves the increase in 'number of organisms through the process of reproduction. 3). Competition and Co-action. It involves the development of intraspecific as well as interspecific competition among the members due to their large number but limited food and space; and development of positive and negative interspecific as well as intraspecific interactions between them. 4). Reaction. It involves the modification of the environment through the influence of living organisms. The modified area becomes less favourable for the existing community so it is sooner or later replaced by another community called seral community and the process is repeated. The whole sequence of communities that replaces one another in the given area is called a sere and various communities constituting the sere are called seral communities. 5). Stabilization (Climax). In this, the final terminal community becomes more or less stabilized for a longer period of time which can maintain itself in equilibrium with the climate of the area, this final community is called climax community and the final stage is called climax stage. The climax community is the most complex and stable, providing food and variety of niches for animals. The climax stage is reached when the existing climax community can tolerate the conditions created by itself and there are no more successful species to replace them. But sometimes there is retrogressive succession in which the organisms exert some destructive effects and the process of succession become retrogressive instead of progressive e.g. replacement of a forest community by a shrubby or grassland community. Hydrosere: Hydrosere, also called hydrarch, involves the ecological succession in the newly formed pond or lake. The various stages together with their chief components of plant species are as under; 1). Phytoplankton stage: In the initial stage of succession algal spores are brought in the body of water. The simple forms of life like bacteria, algae and many other aquatic plants (phytoplankton) and animals (zooplankton) floating in water are the pioneer colonizers. All these organisms add large amount of organic matter and nutrients due to their various life activities and after their death, they settle at the bottom of pond to form a layer of muck. 2. Submerged stage: The phytoplankton stage is followed by submerged plant stage. Some rooted submerged hydrophytes begin to appear on the new substratum. These include Potamogeton, Myriophyllum, Ranunculus, Utricularia, Ceratophyllum,Vallisneria, Chara, etc. When these plants die their remains are deposited at the bottom of the Page 21 of 22 ponds or lakes. As this process of stratification progresses, the body of water becomes more and more shallow, consequently the habitat becomes less suited for the submerged vegetation but more favourable for other plants. 3. Floating stage: When the depth of water becomes less, then the floating plants make their appearance gradually in that area. In the beginning the submerged and floating plants grow intermingled but in the course of time the submerged plants are replaced completely. The most tolerant species in the area are able to reproduce and perpetuate. Their broad leaves floating on the water surface check the penetration of light to deeper layer of water and cause the death of submerged plants. More water and air borne soil and dead remains of plants are deposited at the bottom. Thus, the substratum rises up invertical direction. Important floating plants that replace the submerged vegetation are Nelumbo, Trapa, Pistia, and Nymphaea, etc. 4. Reed-swamp stages: When the ponds and lakes become too shallow and the habitat is changed so much that it becomes less suited to the floating plants, Under these conditions, the floating plants start disappearing gradually and their places are occupied successfully by the plants e.g. Typha, Sagittaria etc. The foliage leaves of such plants are exposed much above the surface of water and roots are generally found either in mud or submerged in water. The foliage leaves form a cover over submerged and floating plants and thus they cut off light from the plant’s underneath them. Further deposition of soil and plant debris at the bottom reduces the depth of water and makes the habitat less suitable for the pre-existing plants. and consequently new successional step follows. 5. Sedge Marsh or Meadow stage: The filling process finally results in a marshy soil which may be too dry for the plants of pre-existing community. Now the plants well adapted to new habitat begin to appear in the pre-existing community in mixed state. Important plants that are well suited to marshy habitat are the members of Cyperaceae and Gramineae e.g. Carex Juncus, are the first invaders of marshy area. As these plants grow most luxuriantly in the marshes, they modify the habitats in several ways. They absorb and transpire a large quantity of water and also catch and accumulate plant debris and wind and water borne soil particles. Consequently, a dry habitat results which may be totally unfit for the growth of normal hydrophytes. Gradually the mesophytes start appearing and after some time the sedge vegetation is totally replaced by them. 6. Woodland stage: In the beginning some shrubs and later medium sized trees form open vegetation or woodland. These plants produce more shade and absorb and transpire large quantity of water. Thus, they render the habitat dry. Shade loving herbs may also grow under the trees and shrubs. The prominent plants of woodland community are species of Acacia, Cassia, Terminalia, Salix, Populus etc. 7. Climax forest: After a very long time the hydrosere may lead to the development of climax vegetation. As the level of soil is raised much above the water level by progressive accumulation of humus and soil particles, the habitat becomes drier and certainly well aerated. In such a habitat, well adapted self-maintaining and self-reproducing, nearly stable and uniform plant community consisting mostly of woody trees develops in the form of mesophytic forest. In the climax forest, all types of plants are met with. Herbs, shrubs, mosses and shade loving plants represent their own communities. At the climax stage, a complete harmony develops between plant community and habitat.

Lithosere:

It is a type of xerosere and involves the ecological succession on bare rock surfaces.

Stages in a Lithosere. 1). Crustose lichens stage: It forms the pioneer community in a lithosere and is represented by lichen species like Graphis Rhizocarpon; Rinodina and Lacanora. The lichens can tolerate desiccation. These produce organic acids which cause weathering of rocks so that minerals essential Page 22 of 22 for proper growth of lichens are released. The lichens hold the fine particles of rock and sand to initiate soil formation. This invites the foliose type lichens. 2). Foliose lichens stage: It includes the lichens like Pamellia, Dermatocarpon etc. Which are large sized lichens with leafy thalli. These foliose lichens retain more water and are able to accumulate dust particles which help in further formation of the substratum. The weathering of rocks and its mixing with humus leads to the development of a fine soil layer on the rock surface which favors the upcoming of hardy mosses. 3). Moss stage: It is characterized by extensive growth of xerophytic mosses like Polytrichum, Torula and Grimmia on thin soil layer on rock surface. Their death and decomposition add more soil and organic matter so the thickness of soil increases. Weathering of rocks also continues. The soil now remained moist for longer periods which favour the growth of moisture-loving mosses like Hypnum, Bryum etc. 4). Herbs stage: The mat formed by mosses on the partially fragmented rock becomes suitable for the germination of seeds of annual hardy grasses like Eleusin, Aristida etc. These grasses have more sand binding properties. Their death and decomposition accumulate more soil so the annual grasses are replaced by perennial grasses like Cymbopogon, Heteropogon etc. 5). Shrub stage: Due to further weathering of rocks and death of the herbs, more soil is accumulated. So the habitat becomes suitable for the growth of shrubs like Rhus, Phytocarpus, Zizyphus, Caparis etc. The shrubs are large in size and their roots penetrate more deeply in the rocky substratum causing more weathering and soil formation. This favours the invasion of the area by next seral stage. 6): Forest stage. It is a climax community in lithosere and is formed of several hardy trees. Further weathering of rocks and increasing humus content of the soil favors the growth of more trees. The vegetation finally becomes mesophytic. Type of climax community depends upon the climate e.g a rainforest in a moist tropical area.

Lithosere

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Unit 2 (Botany) B Sc 2nd Semester Ecosystem and Phytogeography Concept of an Ecosystem: Living organisms cannot live isolated from their non-living environment because the latter provides materials and energy for the survival of the former i.e. there is interaction between a biotic community and its environment to produce a stable system; a natural self-sufficient unit which is known as an ecosystem. An ecosystem is, therefore, defined as a natural functional ecological unit comprising of living organisms (biotic community) and their non-living (abiotic or physico - chemical) environment that interact to form a stable self-supporting system. A pond, lake, desert, grassland, meadow, forest etc. are common examples of ecosystems. Structure and Function of an Ecosystem: Each ecosystem has two main components: (1) Abiotic; (2) Biotic (1) Abiotic Components: The non-living factors or the physical environment prevailing in an ecosystem form the abiotic components. They have a strong influence on the structure, distribution, behaviour and inter-relationship of organisms. Abiotic components are mainly of two types: (a) Climatic Factors: Which include rain, temperature, light, wind, humidity etc. (b) Edaphic Factors: Which include soil, pH, topography minerals etc.? The functions of important abiotic components are given below: Soils are much more complex than simple sediments. They contain a mixture of weathered rock fragments, highly altered soil mineral particles, organic matter, and living organisms. Soils provide nutrients, water, a home, and a structural growing medium for organisms. The vegetation found growing on top of a soil is closely linked to this component of an ecosystem through nutrient cycling. The atmosphere provides organisms found within ecosystems with carbon dioxide for photosynthesis and oxygen for respiration. The processes of evaporation, transpiration and precipitation cycle water between the atmosphere and the Earth’s surface. Solar radiation is used in ecosystems to heat the atmosphere and to evaporate and transpire water into the atmosphere. Sunlight is also necessary for photosynthesis. Photosynthesis provides the energy for plant growth and metabolism, and the organic food for other forms of life. Most living tissue is composed of a very high percentage of water, up to and even exceeding 90%. The protoplasm of a very few cells can survive if their water content drops below 10%, and most are killed if it is less than 30-50%. Water is the medium by which mineral nutrients enter and are trans-located in plants. It is also necessary for the maintenance of leaf turgidity and is required for photosynthetic chemical reactions. Plants and animals receive their water from the Earth’s surface and soil. The original source of this water is precipitation from the atmosphere. (2) Biotic Components: The living organisms including plants, animals and micro-organisms (Bacteria and Fungi) that are present in an ecosystem form the biotic components. On the basis of their role in the ecosystem the biotic components can be classified into three main groups: I). Producers: II). Consumers: III). Decomposers or Reducers.

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I). Producers: The green plants have chlorophyll with the help of which they trap solar energy and change it into chemical energy of carbohydrates using simple inorganic compounds namely water and carbon dioxide. This process is known as photosynthesis. As the green plants manufacture their own food they are known as Autotrophs (i.e. auto = self, trophos = feeder) The chemical energy stored by the producers is utilised partly by the producers for their own growth and survival and the remaining is stored in the plant parts for their future use. II). Consumers: The animals lack chlorophyll and are unable to synthesise their own food. Therefore, they depend on the producers for their food. They are known as heterotrophs (i.e. heteros = other, trophos = feeder) The consumers are of four types, namely: i). Primary Consumers or First Order Consumers or Herbivores: These are the animals which feed on plants or the producers. They are called herbivores. Examples are rabbit, deer, goat, cattle etc. ii). Secondary Consumers or Second Order Consumers or Primary Carnivores: The animals which feed on the herbivores are called the primary carnivores. Examples are cats, foxes, snakes etc. iii). Tertiary Consumers or Third Order Consumers: These are the large carnivores which feed on the secondary consumers. Example is Wolves. iv). Quaternary Consumers or Fourth Order Consumers or Omnivores: These are the largest carnivores which feed on the tertiary consumers and are not eaten up by any other animal. Examples are lions and tigers. III) Decomposers or Reducers: Bacteria and fungi belong to this category. They breakdown the dead organic materials of producers (plants) and consumers (animals) for their food and release to the environment the simple inorganic and organic substances produced as by-products of their metabolisms. These simple substances are reused by the producers resulting in a cyclic exchange of materials between the biotic community and the abiotic environment of the ecosystem. The decomposers are known as Saprotrophs (i.e., sapros = rotten, trophos = feeder)

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Energy Flow in an Ecosystem Energy has been defined as the capacity to do work. Energy exists in two forms potential and kinetic. Potential energy is the energy at rest {i.e., stored energy) capable of performing work. Kinetic energy is the energy of motion (free energy). It results in work performance at the expense of potential energy. Conversion of potential energy into kinetic energy involves the imparting of motion. The source of energy required by all living organisms is the chemical energy of their food. The chemical energy is obtained by the conversion of the radiant energy of sun. The radiant energy is in the form of electromagnetic waves which are released from the sun during the transmutation of hydrogen to helium. The chemical energy stored in the food of living organisms is converted into potential energy by the arrangement of the constituent atoms of food in a particular manner. In any ecosystem there should be unidirectional flow of energy.

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This energy flow is based on two important Laws of Thermodynamics which are as follows

1). The first law of Thermodynamics: It states that the amount of energy in the universe is constant. It may change from one form to another, but it can neither be created nor destroyed. Light energy can be neither created nor destroyed as it passes through the atmosphere. It may, however, be transformed into another type of energy, such as chemical energy or heat energy. These forms of energy cannot be transformed into electromagnetic radiation. 2). The second law of Thermodynamics: It states that non-random energy (mechanical, chemical, radiant energy) cannot be changed without some degradation into heat energy. The change of energy from one form to another takes place in such a way that a part of energy assumes waste

Page 4 of 18 form (heat energy). In this way, after transformation the capacity of energy to perform work is decreased. Thus, energy flows from higher to lower level. Main source of energy is sun. Approximately 57% of sun energy is absorbed in the atmosphere and scattered in the space. Some 35% is spent to heat water and land areas and to evaporate water. Of the approximately 8% of light energy striking plant surface, 10% to 15% is reflected, 5% is transmitted and 80 to 85% is absorbed; and an average of only 2% (0.5 to 3.5%) of the total light energy striking on a leaf is used in photosynthesis and rest is transformed into heat energy. Energy flow in Ecosystems: Living organisms can use energy in two forms radiant and fixed energy. Radiant energy is in the form of electromagnetic waves, such as light. Fixed energy is potential chemical energy bound in various organic substances which can be broken down in order to release their energy content. Organisms that can fix radiant energy utilizing inorganic substances to produce organic molecules are called autotrophs. Organisms that cannot obtain energy from abiotic source but depend on energy- rich organic molecules synthesized by autotrophs are called heterotrophs. Those which obtain energy from living organisms are called consumers and those which obtain energy from dead organisms are called decomposers When the light energy falls on the green surfaces of plants, a part of it is transformed into chemical energy which is stored in various organic products in the plants. When the herbivores consume plants as food and convert chemical energy accumulated in plant products into kinetic energy, degradation of energy will occur through its conversion into heat. When herbivores are consumed by carnivores of the first order (secondary consumers) further degradation will occur. Similarly, when primary carnivores are consumed by top carnivores, again energy will be degraded.

Trophic level: The producers and consumers in ecosystem can be arranged into several feeding groups, each known as trophic level (feeding level). In any ecosystem, producers represent the first trophic level, herbivores present the second trophic level, primary carnivores represent the third trophic level and top carnivores represent the last level.

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Food Chain: In the ecosystem, green plants alone are able to trap in solar energy and convert it into chemical energy. The chemical energy is locked up in the various organic compounds, such as carbohydrates, fats and proteins, present in the green plants. Since virtually all other living organisms depend upon green plants for their energy, the efficiency of plants in any given area in capturing solar energy sets the upper limit to long-term energy flow and biological activity in the community. The food manufactured by the green plants is utilized by themselves and also by herbivores. Animals feed repeatedly. Herbivores fall prey to some carnivorous animals. In this way one form of life supports the other form. Thus, food from one trophic level reaches to the other trophic level and in this way a chain is established. This is known as food chain. A food chain may be defined as the transfer of energy and nutrients through a succession of organisms through repeated process of eating and being eaten. In food chain initial link is a green plant or producer which produces chemical energy available to consumers. For example, marsh grass is consumed by grasshopper, the grasshopper is consumed by a bird and that bird is consumed by hawk. Thus, a food chain is formed which can be written as follows: Marsh grass → grasshopper → bird → hawk Food chain in any ecosystem runs directly in which green plants are eaten by herbivores, herbivores are eaten by carnivores and carnivores are eaten by top carnivores. Man forms the terrestrial links of many food chains. Food chains are of three types: 1. Grazing food chain 2. Parasitic food chain 3. Saprophytic or detritus food chain 1). Grazing food chain: The grazing food chain starts from green plants and from autotrophs it goes to herbivores (primary consumers) to primary carnivores (secondary consumers) and then to secondary carnivores (tertiary consumers) and so on. The gross production of a green plant in an ecosystem may meet three fates—it may be oxidized in respiration; it may be eaten by herbivorous animals and after the death and decay of producers it may be utilized by decomposers and converters and finally released into the environment. In herbivores the assimilated food can be stored as carbohydrates, proteins and fats, and transformed into much more complex organic molecules. The energy for these transformations is supplied through respiration. As in autotrophs, the energy in herbivores also meets three routes respiration, decay of organic matter by microbes and consumption by the carnivores. Likewise, when the secondary carnivores or tertiary consumers eat primary carnivores, the total energy assimilated by primary carnivores or gross tertiary production follows the same course and its disposition into respiration, decay and further consumption by other carnivores is entirely similar to that of herbivores. Thus, it is obvious that much of the energy flow in the grazing food chain can be described in terms of trophic levels as outlined below:

2). Parasitic food chain: It goes from large organisms to smaller ones without outright killing as in the case of predator. 3). Detritus food chain: The dead organic remains including metabolic wastes and exudates derived from grazing food chain are generally termed detritus. The energy contained in detritus is not lost in ecosystem as a whole, rather it serves as a source of energy for a group of organisms called detritivores that are separate from the grazing food chain. The food chain so formed is called detritus food chain

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In some ecosystems more energy flows through the detritus food chain than through grazing food chain. In detritus food chain the energy flow remains as a continuous passage rather than as a stepwise flow between discrete entities. The organisms in the detritus food chain are many and include algae, fungi, bacteria, slime moulds, actinomycetes, protozoa, etc. Detritus organisms ingest pieces of partially decomposed organic matter, digest them partially and after extracting some of the chemical energy in the food to run their metabolism, excrete the remainder in the form of simpler organic molecules. The waste from one organism can be immediately utilized by a second one which repeats the process. Gradually, the complex organic molecules present in the organic wastes or dead tissues are broken down to much simpler compounds, sometimes to carbon dioxide and water and all that are left are humus. In a normal environment the humus is quite stable and forms an essential part of the soil. Schematic representation of detritus food chain is given in Food web: Many food chains exist in an ecosystem, but as a matter of fact these food chains are not independent. In ecosystem, one organism does not depend wholly on another. The resources are shared specially at the beginning of the chain. The marsh plants are eaten by variety of insects, birds, mammals and fishes and some of the animals are eaten by several predators. Similarly, in the food chain grass → mouse → snakes → owls, sometimes mice are not eaten by snakes but directly by owls. This type of interrelationship interlinks the individuals of the whole community. In this way, food chains become interlinked. A complex of interrelated food chains makes up a food web. Food web maintains the stability of the ecosystem. The greater the number of alternative pathways the more stable is the community of living things. .

Food web

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Ecological Pyramid An ecological pyramid (also called trophic pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bio productivity at each trophic level in a given ecosystem. Biomass is the amount of living or organic matter present in an organism. Biomass pyramids show how much biomass is present in the organisms at each trophic level. Ecological pyramids begin with producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat herbivores, then carnivores that eat those carnivores, and so on). The highest level is the top of the chain. An ecological pyramid of biomass shows the relationship between biomass and trophic level by quantifying the biomass present at each trophic level of an ecological community at a particular time. It is a graphical representation of biomass (total amount of living or organic matter in an ecosystem) present in unit area in different tropic levels. Types There are 3 types of ecological pyramids as described as follows: 1). Pyramid of energy 2). Pyramid of numbers 3). Pyramid of biomass. 1). Pyramid of Energy: The pyramid of energy or the energy pyramid describes the overall nature of the ecosystem. During the flow of energy from organism to other, there is considerable loss of energy in the form of heat. The primary producers like the autotrophs there is more amount of energy available. The least energy is available in the tertiary consumers. Thus, shorter food chain has more amount of energy available even at the highest trophic level. ▪ The energy pyramid always upright and vertical. ▪ This pyramid shows the flow of energy at different trophic levels. ▪ It depicts the energy is minimum as the highest trophic level and is maximum at the lowest trophic level. At each trophic level, there is successive loss of energy in the form of heat and respiration,etc.

2). Pyramid of Numbers: The pyramid of numbers depicts the relationship in terms of the number of producers, herbivores and the carnivores at their successive trophic levels. There is a decrease in the number of individuals from the lower to the higher trophic levels. The number pyramid varies from ecosystem to ecosystem. There are three of pyramid of numbers: i). Upright pyramid of number ii). Partly upright pyramid of number and iii). Inverted pyramid of number.

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i). Upright Pyramid of Number: This type of pyramid number is found in the aquatic and grassland ecosystem, in these ecosystems there are numerous small autotrophs which support lesser herbivores which in turn support smaller number of carnivores and hence this pyramid is upright ii). Partly Upright pyramid of Number It is seen in the forest ecosystem where the number of producers are lesser in number and support a greater number of herbivores and which in turn support a fewer number of carnivores. iii). Inverted Pyramid of Number This type of ecological pyramid is seen in parasitic food chain where one primary producer supports numerous parasites which support more hyper parasites.

3). Pyramid of Biomass: The pyramid of biomass is more fundamental, they represent the quantitative relationships of the standing crops. In this pyramid there is a gradual decrease in the biomass from the producers to the higher trophic levels. The biomass here the net organisms collected from each feeding level and are then dried and weighed. This dry weight is the biomass and it represents the amount of energy available in the form of organic matter of the organisms. In this pyramid the net dry weight is plotted to that of the producers, herbivores, carnivores, etc. There are two types of pyramid of biomass, they are: i). Upright pyramid of biomass and ii). Inverted pyramid of biomass. i). Upright Pyramid of Biomass: This occurs when the larger net biomass of producers supports a smaller weight of consumers. Example: Forest ecosystem. ii). Inverted Pyramid of Biomass: This happens when the smaller weight of producers supports consumers of larger weight. Example: Aquatic ecosystem

Figure 1Inverted Pyramid of Biomass of aquatic ecosystem

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Productivity: In ecology productivity refers to the rate of formation of biomass in the ecosystem. It can be referred to as the energy accumulated in the plants by photosynthesis. It is expressed in units of mass per unit volume (or surface per unit time). There are two types of Productivity namely 1). Primary Productivity 2). Secondary productivity 1). Primary Productivity: The fraction of fixed energy a trophic level passes on to the next trophic level is called production. Green plants fix solar energy and accumulate it in organic forms as chemical energy. Since it is the first and basic form of energy storage, the rate at which the energy accumulates in the green plants or producers is known as primary productivity. Primary productivity is the rate at which energy is bound or organic material is created by photosynthesis per unit area of earth’s surface per unit time. It is most often expressed as energy in calories / cm2 / yr or dry organic matter in g / m2 / yr (g/m2 x 8.92 = lb / acre). The amount of organic matter present at a given time per unit area is called standing crop or biomass and as such productivity, which is a rate, is quite different from biomass or standing crop. The standing crop is usually expressed as dry weight in g/m2 or kg/m2 or t/ha (metric tons) or 106g/hectare. Primary productivity is the result of photosynthesis by green plants including algae of different colours. Bacterial photosynthesis or chemosynthesis, although of small significance may also contribute to primary productivity. There are two types of primary productivity i). Gross Primary productivity ii). Net primary productivity i). Gross Primary productivity: The total solar energy trapped in the food material by photosynthesis is referred to as gross primary productivity (G.P.P.). This depends upon the photosynthetic activity and environmental factors. ii). Net primary productivity: A good fraction of gross primary production is utilized in respiration of green plants. This is estimated by the gross productivity minus energy lost in respiration. NPP = GPP – Energy lost by respiration So, the amount of energy bound in organic matter per unit area and time that is left after respiration in plants is net primary production (N.P.P.) or plant growth. Only the net primary productivity is available for harvest by man and other animals. 2). Secondary Productivity: The rates at which the heterotrophic organisms resynthesize the energy-yielding substances is termed as secondary productivity. Secondary productivities are the productivities of animals and saprobes in communities. The amount of energy stored in the tissues of consumers or heterotrophs is termed as net secondary production and the total plant material ingested by herbivores is grass secondary production. Total plant material ingested by herbivores minus the materials lost as faeces is equal to Ingested Secondary Production.

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Environmental factors affecting the production processes in an ecosystem are as follows:

1). Solar radiation and Temperature 2). Moisture. Leaf water potential, soil moisture and precipitation fluctuation and transpiration. 3). Mineral nutrition. Uptake of minerals from the soil, rhizosphere effects, fire effects, salinity, heavy metals, nitrogen metabolism. 4). Biotic activities. Grazing, above ground herbivores, below ground herbivores, predators and parasites, diseases of primary producers. 5). Impact of human population. Pollutions of different sorts, ionizing radiations like atomic explosions, etc. Biogeochemical Cycles (Cycles of Matter): A biogeochemical cycle is defined as the movement of elements through organisms and the environment. A way to remember this is to break apart the word 'biogeochemical' into pieces Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another through cycles that connect living things to the earth. The four chemicals that make up 95% of living things are; carbon, hydrogen, oxygen and nitrogen. These elements are constantly being cycled through living and non-living organic matter. Carbon Cycle: The series of processes by which carbon compounds are interconverted in the environment, involving the incorporation of carbon dioxide in to living tissues by photosynthesis and its return to the atmosphere through respiration, the decay of dead organisms, and the burning of fossil fuels. Together, photosynthesis and cellular respiration form the basis of the carbon cycle. Carbon is found in all of the major macromolecules (carbohydrates, nucleic acids, proteins and lipids) which are necessary for all living systems. The Earth's atmosphere contains carbon in the form of carbon dioxide (CO2). There are five major reservoirs of carbon: 1). The atmosphere 2). the terrestrial biosphere 3). oceans 4). ocean sediments 5). the earth's interior. Processes of the Carbon Cycle:

Photosynthesis: During photosynthesis, plants and other autotrophs use CO2 along with water and solar energy, to build organic molecules (carbohydrates), thus storing the carbon for themselves and other organisms. Cellular Respiration: Both autotrophs and heterotrophs use oxygen to break down carbohydrates during cellular respiration. Consumers obtain energy-rich molecules that contain carbon by eating plants and animals. Volcanic Eruptions and geothermal vents: carbon from deep within the earth's interior is brought back to the surface during eruptions of steam, gasses and lava Decomposition: Carbon is returned to the environment through decomposers and cellular respiration (breathing releases CO2 back to the atmosphere). Combustion: When wood or fossil fuels are burned, the chemical reaction releases carbon dioxide back into the atmosphere

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Deposition: Coal, petroleum, and calcium carbonate rock are deposited in sediment and underground. Calcium carbonate deposits are eroded by water to form carbon dioxide. Large amounts of carbon are tied up in wood, only returning to the atmosphere when wood is burned.

Nitrogen Cycle: All organisms need nitrogen, an important nutrient, to make proteins and nucleic acids. Most nitrogen is found in the atmosphere (80%) as N2, and most living things cannot use it. All organisms rely on the actions of bacteria that are able to transform nitrogen gas into a usable form. Nitrogen- fixing bacteria (Cyanobacteria and Rhizobium) play a key role in the nitrogen cycle. They live in the soil and in the roots of some kinds of plants, such as beans, peas, clover, and alfalfa. These bacteria have enzymes that can break the atmospheric N2 bonds. Nitrogen atoms are then free to bond with hydrogen atoms to form Ammonia (NH3).

Processes of the Nitrogen Cycle: Nitrogen fixation is the conversion of nitrogen gas to ammonia; Ammonia can be absorbed by plants from the soil, and used to make proteins, and enter the food web for consumers. Assimilation: Consumers obtain nitrogen from the plants and animals they eat by digesting the food's proteins and using it to make their own proteins Ammonification: Decomposers return the nitrogen from the remains of dead plants and animals back to the soil. Nitrogen is also returned from animal and plant waste by decomposers (dung, urine, leaves and bark). Through ammonification, nitrogen that would be lost, is recycled back into the ecosystem.

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Denitrification: Denitrification occurs when anaerobic bacteria (chemoautotrophs) break down nitrates and release nitrogen gas back into the atmosphere. Nitrification: Bacteria convert ammonia into nitrogen compounds that plants can utilize more easily. Autotrophs (plants) are therefore dependent on nitrogen-fixing bacteria, and all other organisms are dependent on autotrophs!

Phosphorus Cycle: It is the biogeochemical cycle that describes the movement of phosphorus through lithosphere, hydrosphere and biosphere.

Phosphorus is an important element for all forms of life. As phosphate (PO4). It makes up an important part of the structural framework that holds DNA and RNA together. Phosphate is also a critical component of ATP – the cellular energy carrier - as they serve as an energy release for organisms to use in building proteins or contacting muscles. In the human body 80% of the phosphorus is found in teeth and bones. The phosphorus cycle differs from the other major biogeochemical cycles in that it does not include a gas phasebecause at earths normal temperature s and pressures , phosphorus and its various componds are not gas. The largest reservoir of phosphorus is in sedimentary rocks. Processes of the Phosphorus Cycle: When it rains and weathering cause rocks to release phosphate ions and other minerals. This inorganic phosphate is then distributing in soils and water.

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Plants take up inorganic phosphate from the soil. The plants may then be consumed by animals. Once in the plant or animal, the phosphate is incorporated into organic molecules such as DNA. When the plant or animal dies, it decays, and the organic phosphate is returned to the soil. Within the soil, organic forms of phosphate can be made available to plants by bacteria that break down organic matter to inorganic form of phosphorus. This process is known as mineralisation Phosphorus in soil can end up in water ways and eventually oceans. Once there, it can be incorporated into sediments over time.

Biogeographic regions of India In north India has the mighty Himalayas which form strong boundary in north and in the south, we have Indian ocean because of these boundaries India is naturally delimited as a unique geographical unit. India is a megadiverse country with only 2.4 per cent of the total land area of the world, the known biological diversity of the India contributes 8 per cent to the known global biological diversity. Rodgers and Panwar in 1988 first attempted to classify the biogeographical regions of India. Later on, in the year 202 they revised this classification and divided India into 10

Page 14 of 18 biogeographic zones with 26 biotic provinces on the basis of Biota, altitude, moisture, topography, rain fall etc. Each Biogeographical region has characteristic plant and animal life.

S. No. Biogeographical region Biotic provinces i). Ladakh mountains 1 Trans Himalaya ii). Tibetan Plateau

i). North - west Himalaya, 2 The Himalaya ii). West Himalaya, iii). Central Himalaya, iv). East Himalaya) i). Thar 3 The Indian Desert ii). Kutch

i). Punjab Plains 4 The Semi – arid ii). Gujrat- Rajputana

i). Malabar Plains 5 The Western Ghats ii). Western Ghat Mountains

i). Central Highlands

ii). Chota Nagpur 6 The Deccan Peninsula iii). Eastern Highlands iv). Deccan South v). Deccan South Plains i). Upper gigantic plains 7 The Gangetic plain ii). Lower gigantic Plains

i). West Coast 8 The Coasts ii). East Coat, iii). Lakshadweep i). Brahamputra valley 9 The Northeast India ii). North East Hills. i). Andmans 10 The Islands ii). Nicobars

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1). Trans-Himalayan Region: Trans- Himalayan region has an area of about 2.6 million square kms. It includes the high altitude, cold and arid mountain areas of Ladakh, Jammu & Kashmir, North Sikkim, Lahaul and Spiti areas of Himachal Pradesh. This zone has sparse alpine steppe vegetation that harbours several endemic species and is a favourable habitat for the biggest populations of wild sheep and goat in the world and other rare fauna that includes Snow Leopard and the migratory Blacknecked Crane 2). Himalayan Zone: Although Himalayan Zone, constituting 7 percent of countries surface area, but its natural resources like water and forest are immense. The altitudinal range in this region were plants and animals occur is too great, around 6000 metres. Due to variation in climate and geology in this region,

Page 16 of 18 vegetation varies greatly from subtropical forests to the alpine meadows and scrubs. In this region especially in the lower subtropical belt mixed deciduous forests occupy the lowest elevations. These are replaced by Chir pine (Pinus roxiburgii) and then moving ahead in elevation it is replaced by Banj Oak (Quercus leucotrichophora). It is around 2000 metres. The mega fauna of this belt includes Samber and wild boar. In the temperate belt of this region particularly below 3500 metres several forest types occur these include broad leaf mesophyll forests of maple (acer) and other deciduous species. Second type of forest is broad leaf evergreen forest comprised broadly Oaks, Third type is evergreen coniferous forests mainly comprised of deodar Blue pine (Pinus wallichiana), spruce ( Picea smithiana) Silver fir (Abies pindrow). The typical fauna in this region is includes Musk dear, Monal pheasants etc. The sub alpine forests occasionally scrubs. They have Rhododendrons interspersed with alpine meadows. In general, a high proportion of endemic biota has evolved in Himalayan Region. e.g. These are 60 species of different Balsams (Impatience) 3. Indian Desert: It is the eastward extension of Sahara Arabian desert system. It comprises the Thar desert and the Kutch area of western India. Annual rain fall in this region is less than 400 mm. The region shows extreme seasonality of the rainfall, which mostly occur few weeks in the rainy season. The forests in this region comprises of mostly bushy thorny plants e.g. Acacia nilotica, Prosopis cineraria, Salvadora oleoides. There are also unique wild animals like wild sub species of wild Ass confined to Ran of kutch. The desert fox, Indian desert cat, Honbara bustard, are found only in Thar desert. Migratory birds in this region such as Flamingos find their breeding sites place in Ran of Kutch. 4. Semi-Arid Region: It occupies nearly 17 percent of land area in India. It Transends from parts of Punjab in the north to the Tamil Nadu in the south. It has strong biogeographical affinity with west Asia and north Africa. Some of the plants with African affinity in this region include Accacia, Capparis, Grewia etc. Forests in this region comprise of pure stands of Anogeissus pendula, which occur on gentle slopes of mountain ranges called as Aravalli. The large herbivore includes Chowsingha, and Nilgai. The carnivores in this region are represented by Asiatic lions, are now restricted to the national park in Gujrat. 5. The Western Ghats: It extends from Kanyakumari in the extreme southern tip of India to south of Tapti in the north. This western Ghats rise from sea level to an elevation of 2700 metres. This Ghats have the moist green forests which are most extensive. The region is exceptionally rich and contribute about 4000 species of plants, which account nearly about 27 percent of the Indian total flora. The endemism in the region is quite high nearly 1800 plant species are endemic in this region. On the hill slopes there is fertile soil. Forests have been replaced by plantations of Tea, Coffee, Coca, Rubber, Cardamom and other plantation crops. The western Ghats have a number of endemic animals which are unique to this region. These include primate like Nilgiri Langur, Lion tailed Macaque. The rodents are Spiny Dormouse. Amongst Squirrels there are Grizzled giant squirrel. Among the carnivores there are Malabar Civet, Rusty spotted cat, Shifting to Angolates we have Nilgiri Thar. Among the horn bells there are Malabar grey horn bell. All these animals are endemic and unique to this region. 6. The Deccan Plateau: Deccan Plateau is India’s largest biogeographic region making 42 per cent of the total geographical area. The region contains some conserved forests in the states of Madhya Pradesh,

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Maharashtra and Odisha. This is the main region of the deciduous forests in India, Thorn forests and scrub lands and in few smaller areas we have evergreen forests of Sal (Shorea robusta), Teak ( Tectona grandis). These are the precious timber species in the region. 7. The Gangetic Plain This region stretches from the Yamuna river eastwards across the states like UP Bihar, West Bengal and the coastal plains of Orrisa. The region is topographically homogenous for thousands of kilometres right from New Delhi to West Bengal. It represents one of the most fertile agricultural land in the world. There are large number of seasonal swamps, other small wetlands were aquatic vegetation and wild life occur coexistential. Sal (Shorea robusta), represent typical vegetation along the foot hills and also some mixed dry deciduous occur in this region. In its terrain area there are animals like Rhino, Bengal florican, Hispid hare which are unique to this region. 8. North East Region North East Region constitutes 5.2 per cent of the total geographical area. It is richest in biodiversity particularly it shows high endemism. The region includes the major portion of the area that falls under the states of Assam and also the entire states of Manipur, Meghalaya, Mizoram, Nagaland, and Tripura. In biogeographic point of view the region is of quite interest as it is transition zone between the Indian, Indo-Malayan and Indo-Chinese regions. It is the meeting place of Himalayan mountains in the north and peninsular India. From the floristic point of view Khasi and Janita hills are famous for their biodiversity throughout the Asia. About 40 percent of the total area under this region is densely forested. Among the fauna in this region the horn bills, and small carnivorous, which are represented by many species that two are unique to this region only. Some other animals include Rhinoceros, Buffalo, Elephant, Swap deer, Hog deer, Pygmy hog and other types of animals. 9. The Coasts Coastal region constitutes 2.5 per cent of the total geographical area with sandy beaches, mangroves, mud flats, coral reefs and marine angiosperm pastures make them the wealth and health zones of India. Though the coasts have diverse biological diversity but is still least explored. This region coasts include Dolphin especially in estuarian waters, Salt water crocodile, turtles such as Batgur basker of Sundarbans, avifauna of Mangroves, Mudflats, and lagoons. 10. The Islands This constitutes 0.3 per cent of the total geographical area are one of the three tropical moist evergreen forests zones in India. The islands house an array of flora and fauna not found elsewhere. These islands are centres of high endemism and contain some of India’s finest evergreen forests and support a wide diversity of corals. In India, endemic island biodiversity is found only in the Andaman and Nicobar Islands. The islands have 4 species of Marine turtles also the Dolphin and whales have been recorded from this region Concept of Endemism: Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type, Organisms that are indigenous to place are not endemic to it if they are also found elsewhere. The extreme opposite of endemism is cosmopolitan distribution and refers to a taxon which is extremely widespread in many world regions.

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India has a rich endemic flora and fauna. About 33% of the flowering plants , 53% of fresh water fishes, 60% amphibians, 36% reptiles and 10% Mamalian are endemic species.

Types of Endemism: There are two sub categories of endemism 1. Paleoendemism 2. Neoendemism. Paleoendemism: Paleoendemism refers to a species that was formerly widespread but is now restricted to a smaller area. Neoendemic species: Neoendemism refers to a species that has recently appeared which is closely related to the main species or one that has formed following hybridization and is now classified as a separate species. Characters of endemics: 1. They are localized in distribution because of their narrow ecological amplitude and are unable to invade in fresh areas. 2. They lack potentially to migrate because of saturated genomics. 3. Real endemics never migrate while nonendemic have the potential to migrate. 4. The dispersal propagules are not able to sustain during migration to other area. It may be due to physical barriers.

Factors Responsible for Endemism: Factors responsible for the production of endemics are natural. Crossing among the closely related plants growing under favourable conditions and mutations. If the conditions of isolation are developed the effect becomes more pronounced. Endemism is found in isolated e.g. islands, isolated areas etc. According the Wulff 80 of Hawalii islands and 72% of New Zealand is endemic. Mountains also have more endemic species as they are isolated e.g. 70% of Himalayas is endemic. Climate also is one of the factors e.g. North of Himalaya is dry plateau of Tibet and South Himalayan range has alluvial fertile soil.

Endemic species in India: According to Chatterjee the percentage of endemic species of Dicot plants in India is more than 50. Maximum endemic plants are found in the Himalayas and South India. Indo-Gangetic plains have a very small number of endemic species. 1. Rhododendron (Ericaceae), 2. Beaumontia grandiflora (Apocynaceae), 3. Eleusine coracana (Poaceae), 4. Caryota urena (Arecaceae), 5. Aegle marmelos (Rutaceae), 6. Crotolaria juncea (Fabaceae), 7. Ficus religiosa (Moraceae), and 8. Seasamum indicum (Pedaliaceae). The other species belong to families like Rubiaceae (6 genera), Rosaceae, Asteraceae, Primulaceae, Acanthaceae

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Unit 3 (Botany) B. Sc. 2nd Semester Plant Taxonomy and Classification

Taxonomy: This word Taxonomy is comprised of two Greek words. Taxis means arrangement and nomose means Law. Taxonomy deals with the identification, nomenclature and classification of organisms. Term has been given by A. P. de candolle1813 (Augustin Pyramus de Candolle) in his book Theorie Elementaire de la Botanique. Fundamental components of Taxonomy: 1. Identification 2. Description 3. Nomenclature 4. Phylogeny 1. Identification: is the process of recognizing an unknown specimen. It can be achieved with the help of already known taxon available in herbarium through taxonomic literature. It is also called recognition. 2. Description: It is the process of recording various characters of a specimen. These characters are called as diagnostic characters. 3. Nomenclature: It is the process of assigning a correct name to a taxon or specimen as per the rules devised by international code of Botanical nomenclature. 4. Phylogeny: It is the process of working out the evolutionary processes, history and genealogy of the plant. Types of Classification: Classification is the arrangement of organisms into groups on the basis of similarities. These groups are in turn assembled into more inclusive groups, until all organisms have been assembled in to the single most inclusive group. Broadly speaking there are three main classification systems; 1). Artificial Classification 2). Natural classification: 3). Phylogenetic classification: 1). Artificial Classification: This system of classification is based on arbitrary easily observable plant characters such as habit, colour, number, form, or other similar features. These classifications remained dominant from 300 B.C. up to about 1830. There were four eminent botanists who contributed to artificial system of plant classification. I). Theophrastus (370-285 B.C.): He was a Greek naturalist and pupil of Plato and Aristotle. Based on the habit, he classified the plants into four groups: Herbs, Undershrubs, Shrubs and Trees. He described and named about 480 plants and published his work in Historia Plantarum, known as the oldest botanical work in existence. For his contributions, Theophrastus is called the “Father of Botany”. II). John Ray (1627-1705): He was a British botanist. Initially, he proposed his classification in Methodus Plantarum Nova (1682). Later on, he represented his classification in Historia Plantarum (1686-1704) in three volumes. Like other old systems, he classified the plants into herbs and trees and further into Dicotyledons and Monocotyledons. His system was much advanced than the earlier classifications and approached the natural system. III). Carolus Linnaeus (1707-1778): He was a Swedish naturalist. For his outstanding contribution he is called the “Father of Modern Botany”. He published his work in different times since 1730 to final form in 1753. In his book Species Plantarum (contains some 7,300 species described and arranged according to his system of classification). In this book, he constantly used the binomial

Page 2 of 12 system in plant names. The Binomial system consists of two names of a specimen, where the first one is the generic epithet and the second is the specific epithet. This binomial system was used subsequently, even by the modern botanists till date. The classification of Linnaeus is an artificial one. The significance of flower and fruit structures was first recognised by him. He emphasised the basic numerical characteristics of sexual parts i.e., stamens and carpels. Thus, the Linnaeus system is also known as sexual system.

2). Natural classification: It is the system of classification which takes into consideration comparable study of a number of characters so as to bring out natural similarities and dissimilarities and hence natural relationships among the organisms. The system employs those characters which are relatively constant. They include morphological characters, anatomical characters, cytological characters, physiology, ontogeny or development, reproduction, cytochemistry and biochemistry, experimental taxonomy etc. The characteristics are helpful in bringing out maximum number of similarities in a group and comparable differences with other groups of organisms. These systems started with M. Adanson & culminated with Bentham and Hooker. The natural system of classification is certainly better than any artificial system of classification because a). There is stress on actual actual study of each and every organism. b). There is stress on comparative study. c). It brings about affinities on the basis of a number of characters. d). It brings out natural relationships amongst organisms. e). It places only related organisms in a group. f). The system prevents coming together of unrelated organisms. g). The system indicates phylogenetic relationships and the origin of different taxa.

3). Phylogenetic classification: This type of classification system is based evolutionary ancestry. It is based on the evolution of life and shows the genetic relationship among organisms. It generates trees called cladograms, which are groups of organisms that include an ancestor species and its descendants. Classifying organisms on the basis of descent from a common ancestor is called phylogenetic classification. The most widely known phylogenetic systems are those of Engler & Prantl, Hutchinson, Takhtajan etc.

Bentham & Hooker’s System of Classification: It is a natural system of classification and is based on important characters of the plants. Even today this system is being followed in India, United Kingdom and several other commonwealth countries. It is also used in a number of herbaria and botanical gardens all over the world. It is a well known and widely accepted classification of seeded plants. it was proposed by two English botanists George Benthum (1800-1884) and Sir Joseph Dalton Hooker (1817-1911). This system of classification was published in Genera Plantarum in three volumes and they have described 97,205 species of seeded plants in 202 orders (now referred to as families). In Benthum and Hookers classification of plants, the present-day orders were referred to as cohorts and families as orders. The following is the summary of Bentham & Hooker‟s classification

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Class 1. Dicotyledons Seeds with two cotyledons, flowers pentamerous or tetramerous, leaves net veined. Sub Class 1. Polypetalae Sepals and petals distinct, petals free Series 1. Thalamiflorae: Flowers hypogynous stamens many disc absent). Orders: 06 Ranales, Parietals, Guttiferales, Malvales, Caryophyllineae, Polygalineae. Series 2. Disciflorae: Flowers hypogynous stamens with many disc present below the ovary Orders: 04 Geranials, Celastrales, Olacales, Sapindales. Series 3. Calyciflorae F lowers perigynous or epigynous. Orders: 05 Rosales, Ficoidales, Myrtales, Umbellales, Passiflorals

Sub Class 2. Gamopetalae Sepals and petals distinct, petals united. Series 1. Inferae Ovary inferior. Orders: 03 Rubiales, Campanales, Asterales Series 2. Heteromerae Ovary superior, stamens in one or two whorls, carpels more than two. Orders: 03 Ericales , Ebenaels, Primulales. Series 3. Bicarpellatae Ovary superior, stamens in one whorl, carpels two. Orders: 04 Gentianales, Polemoniales, Personales and Lamiales. Sub Class 3. Monochlamydeae Flowers apetalous Perianth lacking or if present not differentiate into sepals and petals Series 1. Curvembryeae Embryo coiled ovule usually one. Series 2. Multiovulate aquatica Aquatics plants with numerous ovule. Series 3. Multiovulate terrestres T errestrial plants with numerous ovule. Series 4. Microembryeae Embryo minute. Series 5. Daphnales One carpel and one ovule. Series 6. Achlamydosporae O vary inferior, unilocular, with 1-3 ovule. Series 7. Unisexuales Flowers unisexual. Series 8. Ordines anomaly: Uncertain relationship

Class 2. Gymnospermae: Ovules naked

Class 3. Monocotyledonae: Flowers trimerous, venation parallel.

Series 1. Microspermae: Ovary inferior, seeds minute). Series 2. Epigynae Ovary inferior, seeds large. Series 3. Coronarieae: Ovary superior, carpels united, perianth coloured

Series 4. Calycineae: Ovary superior, carpels united, perianth green. Series 5. Nudiflorae Ovary superior, perianth absent. Series 6. Apocarpae Ovary superior, carpels more than one, free. Series 7. Glumaceae Ovary superior, perianth reduced, flowers enclosed in glumes.

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Angiosperm Phylogeny Group (APG) System

The Angiosperm Phylogeny Group, or APG, refers to an international group of systematic botanists who came together to establish a consensus view of the taxonomy of flowering plants (angiosperms) that would reflect new knowledge about their relationships based upon phylogenetic studies. It relied on the synthesis of information from the disciplines of morphology, anatomy, embryology, phytochemistry and more strongly on molecular studies with reference to DNA sequences of two chloroplast genes (cpDNA; atpB and rbcL) and one gene coding for ribosomes (nuclear ribosomal 18s DNA). Till 2010, three versions of classifications have been proposed by this group that was published in 1998, 2003 and 2009, each superseding the previous systems. An important motivation for the group was what they viewed as deficiencies in prior angiosperm classifications, which were not based on monophyletic groups (i.e. groups consisting of all the descendants of a common ancestor).

APG publications are increasingly influential, with a number of major herbaria changing the arrangement of their collections to match the latest APG system. In this system names (previously used) are not used above the level of order, name clades being used instead. APG CLASSIFICATION (APG, 1998) APG 1998 recognized 462 families, which were grouped into 40 monophyletic orders classified under few informal monophyletic higher groups: monocots, commelinoids, eudicots, core eudicots, rosids including eurosids I and eurosids II, asterids including eausterids I and euasterids II. Many families were not classified to order because their positions were either uncertain or unknown.

APG II (2003) Further advances in flowering plant phylogenetic research, an updated version of the APG classification (APG II) was proposed in 2003. The APG II classification recognized 457 families (5 less than APG 1998) and 45 orders (5 more than APG 1998). Of the 45 orders, 44 are placed in 11 informal groups which were considered more or less monophyletic. The list of unplaced families in the beginning has been reduced to 4 and uncertain families towards the end to 9.

APG III (2009) To fill further gaps in APG II and to develop a much more stabilized classification, with recommendations of different scientist groups around the world, a revised and updated version of APG was published in October, 2009 by a team of 8 scientists in the name of APG III. APG III recognizes 413 families. Except ten families, viz., Dasypogonaceae, Ceratophyllaceae, Sabiaceae, Dilleniaceae, Boraginaceae, Vahliaceae, Icacinaceae, Metteniusaceae, Oncothecaceae, Cynomoriaceae and Apodanthaceae. Rest of the 403 families are assigned to 59 orders. Of these 59 orders, Amborellales, Nymphaeales, Austrobaileyales and Chloranthales (covering 8 families) are unplaced, i.e. not included under any clade, and kept in the begining. The remaining 55 orders are assigned to 11 clades or groups. Order Ceratophyllales is considered as probable sister of eudicots. An abstract of APG III classification with respect to groups, orders and families is presented in table shown below

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Of the 413 families of APG III, 121 are monotypic, represented by a single genus and 28 of them are represented by single species. As per the current update information given in the APG website (Stevens, 2001 onwards), the largest family is Orchidaceae (27,800 species/880 genera). Other dominant families are: Asteraceae (23,600 species / 1620 genera), Fabaceae (19,560/745), Rubiaceae (13,150 /611) and Poaceae (11,337/ 707).

ABSTRACT OF APG CLASSIFICATION

Clade/ Group Orders (No. of orders/families) (No. of. families) - Unplaced Orders Amborellales (1) ; Nymphaeales (3) Austrobaileyales (3); Chloranthales (1) MAGNOLIIDS (4/20 ) Canellales (2) ; Piperales (5); Laurales (7) Magnoliales (6) MONOCOTS (7/47) Acorales (1) ; Alismatales (13); Petrosaviales (1); Dioscoreales (3); Pandanales (5), Liliales (10) ; Asparagales (14)

COMMELINIDS (4/31) Unplaced family-Dasypogonaceae Arecales (1) ; Commelinales (5); Poales (16) Zingiberales (8) PROBABLE SISTER OF EUDICOTS Ceratophyllales (1) (1/1) EUDICOTS (4/14) Ranunculales (7) ; Unplaced family- Sabiaceae Proteales (3) ; Trochodendrales (1); Buxales (2) CORE EUDICOTS (2/17) Gunnerales (2) ; Unplaced family- Dilleniaceae Saxifragales (14) ROSIDS (1/1) Vitales (1) FABIDS (8/73) Zygophyllales (2); Celastrales (2); Oxalidales (7); Malphigiales (35); Cucurbitales (7); Fabales (4); Fagales (7); Rosales (9)

MALVIDS (11/ 102) Geraniales (3); Myrtales (9); Crossosomatales (7); Picramniales (1); Huerteales (3); Brassicales (17) Malvales (10); Sapindales (9); Berberidopsidales (2); Santalales (7); Caryophyllales (34) ASTERIDS (2/28) Cornales (6); Ericales (22)

LAMIIDS (4/40) Unplaced families: Boraginaceae, Vahliaceae, Icacinaceae, Metteniusaceae, Oncothecaceae Garryales (2); Gentianales (5); Lamiales (23),Solanales(5)

CAMPANULIDS (7/29) Aquifoliales (5); Asterales (11); Escalloniales (1); Bruniales (2); Paracryphiales (1); Dipsacales (2); Apiales (7)

TAXA OF UNCERTAIN POSITION 2 families: Apodanthaceae and Cynomoriaceae 3 genera : Gumillea, Petenaea (possibly Malvales) and Nicobariodendron

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Numerical Taxonomy: It the branch of taxonomy which uses mathematical methods to evaluate the observable differences and similarities between taxonomic groups. It is also called Taximetrics. In other words, it is a system of classification in biological systematics which deals with the grouping of organisms through numerical methods of taxonomic units based on their character states. These systems utilize numeric algorithms like cluster analysis rather than using subjective evaluation of their properties for developing classification system. According to Heywood (1967) the numerical taxonomy may be defined as “the numerical evaluation of the similarity between groups of organisms and the ordering of these groups into higher ranking taxa on the basis of these similarities.” The concept of numerical taxonomy was developed by Robert R. Sokal and Peter H.A. Sneath in 1963. They divided numerical taxonomy into 1. Phenetics dealing with classification based on the patterns of overall similarities 2. Cladistics dealing with classification based on the branching patterns of the estimated evolutionary history of the taxa The numerical taxonomy does not produce new data or a new system of classification, but it is rather a new method of organizing data that could help in better understanding of relationships. Adanson (1763), a French botanist, was the first to put forward a plan for assigning numerical valves on the similarity between organisms. He tried to use as many characters as possible for the classification, and such classifications were recognized as Adansonian classification.

Principles of numerical taxonomy Sneath and Sokal (1973) proposed seven major principles for phenetics or numerical Taxonomy. 1. Taxonomy is viewed and practiced as empirical sciences 2. Classifications are based on phenetic similarity. 3.The greater the content of information in the taxa of a classification system, the better a given classification will be. 4. Every character has equal weight in creating natural taxa. 5. The overall similarity between any two entities is the function of the individual similarities in each of the many characters, which are considered for comparison. 6. Distinct taxa can be recognized, because correlation of characters differ in the groups of organisms under study. The science of taxonomy is viewed and practiced as an empirical science. 7. Phylogenetic conclusions can be drawn from the taxonomic structures of a group and also from character correlation, given certain assumptions about evolutionary pathways and mechanisms. Methodology of Phenetics or numerical Taxonomy: 1. Operational Taxonomic Units: The first step in data analysis involves the selection of Taxa for data collection, often called operational taxonomic units (OTUs) and may refer to individual organisms, populations, species, and so on. Once the taxa are selected a list of such taxa is prepared.

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2. Unit taxonomic character or attribute: Taxonomic character is the characteristic that distinguishes one taxon from another. Thus, white flowers may distinguish one species from another with red flower. Hence red and white flower are the two characters. A more practical definition given by numerical taxonomist (Michener and Sokal1957) as a feature which varies from one organism to another, so flower colour is one character (and not white flower and red flower) is a character. and the white flower and red flower are its character -states. Some authors use the term attribute for character state. When selecting a character for numerical analysis, it is important to select a unit character, which may be defined as a taxonomic character of two or more states. Ideally more than 100-unit characters are desirable but should never be less than 60. Preferably the characters selected should be from all the parts and from all the stages of life cycle. As the large number of characters are used, so use of computers becomes necessary for data analysis., because the computers recognise only numerical data, the coding of all the selected characters is prior requirement. 3. Coding of characters Characters are of two types 1. Binary characters: Those unit characters, which exit in two states are called binary characters e.g. Presence or absence of trichomes. They can be represented by the simplest form of coding, where characters are divided into + and – or as 1 and 0. In such cases the positive characters are recorded as + or 1 and the negative characters are recorded as – or 0. In case the organ possessing a given character is missing in an organism the character is scored NC means no comparison. 2. Multistate characters: Those unit characters, which exist in more than two states are called multistate characters Such characters can be coded into number of states 1,2,3 4. Construction of character Taxon matrix: Once the OUTs have been selected and the character and their subsequent coding has been achieved, the data is presented in the form of primary matrix called as character taxon matrix. In the matrix the charters are represented by the columns, while as the taxa along rows. For simple understanding a hypothetical example is used here e.g. there are 6 OTUs S, T, W, X, Y, Z and ten characters. The character taxon matrix will be as follows. OTUs↓ Characters → I II III IV V VI VII VIII IX X S 0 0 0 0 0 0 0 0 1 1 T 0 0 0 1 0 0 1 0 1 1 W 0 1 0 1 0 1 1 0 1 0 X 0 1 0 1 0 1 0 0 1 0 Y 1 1 1 0 1 0 0 1 0 0 Z 1 1 1 0 1 1 0 1 0 0

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5. Measurement of phenetic similarity and Cluster analysis: The next step is to calculate the degree of similarity between every pair of OTU’s. Similarity is calculated by comparing each OUT with each other and usually expressed as percentage, 100% for identical and 0% for no similarity at all. Then a similarity matrix is constructed by tabulating the S coefficients for each one of the taxa. A number of coefficients exists for measuring similarity. One of the simplest and commonly used is the Co-efficient of Association used by Sneath (1957). It is derived as S= Ns/Ns + Nd, where Ns stands for the number of similar features shared by any 2 OTUs and Nd stands for the number of dissimilar features. Taking the above Character X taxon matrix into consideration, we will make a similarity matrix.

S T W X Y Z S 100 T 80 100 W 50 70 100 X 60 60 90 100 Y 30 10 20 20 100 Z 20 0 30 40 90 100

It must be noted that diagonal value in similarity matrix represents self-comparison of OTUs and thus 100% similarity. The values in the triangle above this diagonal line would be similar to the triangle below. Therefore, the effective number of similarity value as such would be t × (t-1)/2. Thus, if 6 OTUs are compared, the number of effective values would be 6 × (6-1)/2 = 15. Construction of phenogram In taxonomy, dendrograms have been used for illustrating relationships. Likewise, in phenetics a phenogram is constructed that graphically expresses the relationships among all the OTUs as shown below; The phenogram reveals the overall similarity relationships among OTUs, S to Z. The vertical lines delimiting groups of OTUs are based on the values of Co-efficient of association. S and T are similar at 80% level. Likewise, W X and Y Z are similar at 90% levels. The S-T and W-X pairs of OTUs are more similar to each other than either pair is to Y-Z pair of OUT (calculated by Co-efficient of association). The level of similarity at which former two pairs (S-T and W-X) of OTUs are connected is based on average values of the pairs S-W, S-X, T-W, T-X, which comes out to be: 50+60+70+60/4 = 60%

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Therefore S-T and W-X pairs of OTUs are 60% similar to each other and joined to each other at 60 of vertical line. Similarly relationships of Y-Z with other OTUs (S-T, W-X) is calculated in same way and comes out to be 20%. Establishment of Phenetic classification: To produce a hierarchical classification from phenogram, it is up to taxonomist to decide about certain threshold values of similarity for different ranks. For instance, a pheneticist decides 85% similarity as the threshold for species, 65% for genera and 45% for families. Then recognise their (OTUs) ranks on the basis of clusters established at the threshold in the phenogram. Family (S,T,W,X,Y,Z)

Genus (S,T,W,X) Genus (Y,Z)

Sub-genus (S,T) Sub-genus (W,X)

Species S Species T Species W Species X Species Y Species Z Cladogram:- Relationship depicting diagrams ae called phylograms. Cladogram is a special type of phylogram constructed through cladistic methodology. Diagram is constructed with the premise in mind that all descendants of a common ancestor should be placed in the same group i.e, group should be monophyletic. If some of the descendents are left out these render the group as paraphyletic these are brought back into the group to make it monophyletic. Similarly, if the group is paraphyletic it is split to create monophyletic taxa. The branching in the diagram is based on the degree of advancement (apomorphy) in the descendants, the longest branching line represent the most advanced group. Phenogram:- is a diagram constructed on the basis of numerical analysis of phonetic data. Such a diagram is the result of utilization of a large number of characters usually from all available fields and involve calculating the similarity between taxa and constructing a diagram through cluster analysis. Such a diagram is very useful, firstly because it is based on a large number of characters, and secondly because a hierarchical classification can be achieved by depicting upon the threshold levels of similarity between taxa assigned to various ranks.

Cladogram Phenogram It is constructed on the basis of cladistic It is constructed on the basis of numerical methodology. taxonomy or taximetrics.

It is a phylogenetic diagram based on the Cluster analysis forms the basis of constructing synapomorphy evidences. phenogram.

It is based on genealogical descent or It is based on a large number of characters derived historical evolution. from many fields of study

Cladogram can be represented by Phenograms can be presented as contour diagram. phylogenetic trees

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Herbaria and their role: A herbarium is a research collection of pressed, dried and labelled plant specimens arranged by a classification scheme. It was Luca Ghini (1490-1556) of Italy who has been the initiator of the art of herbaria. Herbarium specimens are references for plant identification and document plat locations, habitat, abundance and flowering / fruiting periods. Role of herbarium: Some important roles of herbaria are as under: 1. Repository of plant specimens: Primary role of a herbarium is to store dried plant specimens, safeguard these against loss and destruction by insects and make them available for study. 2. Safe custody of type specimens: Type specimens are the principal proof of the existence of species. These are kept in safe custody, often in rooms with restricted access, in several major herbaria. 3. Compilation of Floras, Manuals and Monographs: Herbarium specimens are the ‘original documents’ upon which the knowledge of taxonomy, evolution and plant distribution rests. Floras, Manuals and monographs are largely based on herbarium resources. 4. Training in herbarium methods: Herbaria act as service institutions as they train researchers, doctors, environmentalist for studies and carry facilities for training graduates and undergraduates in herbarium practices, organizing field trips and even expeditions to remote areas. 5. Identification of specimens: The majority of herbaria have a wide range of collection of specimens and offer facilities for identification of plants in the fields of taxonomy, ecology, agriculture, pharmacy etc. 6. Information on geographical distribution: Major herbaria have collections from different parts of the world and thus scrutiny of the specimen’s provider information on the geographical distribution of a taxon. 7. Preservation of Voucher specimens: Voucher specimens preserved in various herbaria provide an index of specimens on which a chromosomal, phytochemical, ultrastructural, micromorphological or any specialized study has been undertake. In the case of a contradictory or doubtful report, the voucher specimens can be critically examined in order to arrive at a more satisfactory conclusion.

Major herbaria of the world: (information update on 17 February 2009 from international websites):

S. No. Name of Herbarium No. of specimens 1 Museum of Natural History Paris, France. 9,377,300 2 New York Botanical garden New York, USA. 7,000,000 3 Komarov botanical institute, Saint petersberg Formerly Liningard 7,000,000 Russia.

4 Royal botanic garden Kew, Surrey, UK. 7,000,000 5 Conservatory and f botanical Garden, Geneva, Switzerland. 6,000,000 6 Missouri Botanical Garden. Saint Louis Missouri, USA 6,000,000

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7 British Museum Natural History, London, UK 5,200,000 8 Combined Herbaria Harvard University Cambridge, Massachusetts, 5,000,500 USA 9 Naturhistorika Riksmuseet, Stockholm Swedden 4,400,000 10 US National Herbarium (Smithsonian) Washington, USA 4,340,000

Important herbaria of India:

S.No. Name of Herbarium No. of specimens 1 The central National Herbarium, Sibhpur , Howrah 2,500,000,

2 Botanical Survey of India, Southern Circle, Coimbatore 200,000

3 Botanical Survey of India, Eastern Circle. Shilong 100,000

4 Botanical Survey of India, Western Circle, Pona 125,000

5 Botanical Survey of India, Northern Circle, Dehradun 60,000

6 Botanical Survey of India, Industrial section, Kolkata 50,000

7 Botanical Survey of India, central Circle, Allahbad 40,000

8 National botanic garden Herbarium, Lucknow 100,000

9 Forest Research Institute Dehradun 300,000

Botanical gardens and their roles: Botanical garden is a controlled staffed institution for the maintenance of a living collection of plants under scientific management for purposes of education and research, together with such libraries, herbaria, laboratories and museums as are essential to its particular undertakings Role of botanical gardens: - The following roles are assigned to botanical gardens: 1. Aesthetic appeal: Botanical gardens have an aesthetic appeal and attract a large number of visitors for observation of general plant diversity, as also the curious plants e.g. the great banyan tree in the Indian botanical garden Kolkata. 2. Material for botanical research: Botanical gardens generally have a wide range of species growing together and offer ready material for botanical research, which can go a long way in understanding taxonomic affinities. 3. On site teaching: Collection of plants is often displayed according to families, genera and habitats, and can be used for self-instruction or demonstration purposes. 4. Conservation: Botanical gardens are now gaining increased importance for their role in conserving genetic diversity, as also in conserving rare and endangered species.

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5. Seed Exchange: More than 500 botanical gardens across the world operate an informal seed exchange scheme, offering annual lists of available species and a free exchange of seeds. 6. Herbarium and Library: Several major botanical gardens of the world have herbaria and libraries as an integral part of their facilities, and offer taxonomic material for research at a single venue. 7. Public services: Botanical gardens provide information to the general public on identification of native and exotic species, methods of propagation, and also supply plant material through sale and exchange. Major botanical gardens of the world: 1. New York Botanical Garden USA, established by Nathaniel Lord Britton in 1891. 2. Royal Botanical gardens, Kew, established by Richard Bennet 1600 3. Missouri Botanical garden USA, established by Henry Shaw in 1859. 4. Pisa Botanical garden, Italy, established by Luca Ghini in 1544. 5. Padua Botanical garden, Italy, established in 1545. 6. Berlin Botanic garden and museum, Berlin- Dahlem established by Grand Duke of Berlin in 1679. 7. Cambridge University Botanical garden, established by J.S. Henslow in 1762. Major botanical gardens of India: 1. Mysore botanical garden, Bangalore established in 1760 by Haider Ali and established as a real botanical garden in 1856. 2. Lloyd botanic garden, Darjeeling established in 1910. 3. National botanic garden, Lucknow established in 1946. 4. Botanical garden of Forest Research Institute, Dehradun established in 1934. 5. Indian Botanical garden, Calcutta, is the largest and oldest botanical garden of India.

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Unit 4 (Botany) B Sc 2nd Semester Identification and Nomenclature Flora:

The term “Flora” refers either to the plants growing in an area surrounded by a geographical boundary or to the group of plants of a particular area or region. Depending on the scope and the area covered the Floras are categorized as 1. Local Flora: covers a limited geographical area, usually a state, county, city a valley or a small mountain range. e.g. Flora of Delhi by J.K. Maheshwari (1963). Flora of Missouri by J.A. Steyermark. 2. Regional Flora: includes a larger geographical area, usually a larger country or a botanical region e.g. Flora of British India by Sir J.D. Hooker (1872-1897). Flora malesiana by C.G. Steens (1948) A Flora covering a country is more appropriately known as National Flora. 3. Continental Flora: covers the entire continent e.g. Flora Europaea by T.G. Turtin et al (1964- 80). Flora Australiensis by G. Bentham (1863-1878). Manual: A manual is a more exhaustive treatment than a Flora always having keys for for identification , description and glossary but generally covering specialized groups of plants .e.g. Manual of cultivated plants by L.H. Baley (1949), manual of aquatic plants by N.C. Fassett (1957). Identification keys: Identification is a basic activity and one of the primary objectives of systematics. It is easy to identify a specimen by the uses of keys than to shuffle through a large number of previously named specimens in a herbarium until a match is found. The use of modern keys for identification is usually credited to J.P. Lamarck (1778). Types of keys: 1. Single access keys. 2. Multi access keys. 1. Single Access keys or Sequential keys: The keys are based on diagnostic (important and conspicuous) characters and as such the keys are known as diagnostic Keys. Most of the keys in use are based on pairs of contrasting characters and as such are dichotomous key. A dichotomous key provides two contrasting choices at each step. Each pair of choices is called couplet and each statement of a couplet is known as lead. For characters having more than two available choices the character can be split to make it dichotomous. Thus, if flowers in a taxon could be red yellow or white the first couplet constitute flowers red vs. non red and the second couplet flowers yellow vs white. The key is designed in such a way that at each step one lead of the couplet will be accepted and the other rejected. The first contrasting characters in each couplet are usually the best contrasting characters and they are known as primary key characters. The characters that follow the lead are referred to as secondary key characters. Each time a choice is made one or more taxa are eliminated. There are different practices regarding the designation of couplet leads. The couplets of the key are numbered; sometimes combination of numbering and lettering are also used. In the numbered key each couplet is numbered i.e, 1,1;2,2 etc or sometimes the first lead of a couplet is distinguished from the second by adding letters a and b respectively to the number, i.e.,1a, 1b; 2a, 2b, etc.

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The first step essential in the identification of a plant involves the use of keys in the determination of the family to which it belongs. Once the family name is determined; next by the use of the key to genera, its generic name is determined; and then by means of the key to species, specific identity of the plant is known. Dichotomous keys are of two types. A. Indented or yoked key B. Bracket or parallel key A. Indented or yoked key: It is most commonly used key in floras and manuals especially when the keys are smaller in size. In this type of key, the statements (leads) of a couplet are arranged in yokes and additionally, the subordinate couplets are indented below the primary one at a fixed distance from the margin. The distance is increasing with each subordinate couplet. Each of successive couplets is indented a fixed distance from the margin of the page. An example of indented key is given bellow in the form of identification of seven common genera of Ranunculaceae i.e. Ranunculus, Adonis, Anemone, Clematis, Caltha, Delphinum, Aquilegia. 1. Ranauculus: Plants herbaceous, fruit achene, distinct calyx and corolla, Spur absent, Petal with nectary at base 2. Adonis: Plants herbaceous, fruit achene, distinct calyx and corolla, Spur absent, Petal without nectary. 3. Anemone: Plants herbaceous, fruit achene, calyx not differentiated, Perianth petaloid Spur absent, 4. Clematis: Plants woody, fruit achene, calyx not differentiated, Perianth petaloid Spur absent, 5. Caltha: Plants herbaceous, fruit follicle, calyx not differentiated, Perianth petaloid Spur absent, 6. Delphinium: Plants herbaceous, fruit follicle, calyx not differentiated, Perianth petaloid Spur one in number. 7. Aquilegia: Plants herbaceous, fruit follicle, calyx petaloid not differentiated from corolla, Spurs five in number. The indented or yoked Key for the taxa under consideration is shown below. 1. Plants woody…………………………………………………………...4. Clematis

1. Plants herbaceous 2. Calyx and corolla differentiated 3. Petals with nectary at base………………………………………1. Ranunculus 3. Petals without nectary at base …………………………………..2. Adonis 2. Calyx and corolla not differentiated 4. Fruit achene………………………………………………….. 3. Anemone

4. Fruit follicle

5. Spur present 6. No. of spurs 1……………………………………………6. Delphinium 6. No of spurs 5………………………………………….....7. Aquilegia 5. Spur absent………………………………………………....5. Caltha B. Bracket or parallel key:

Bracket keys are those keys in which two couplets are always next to each other in consecutive lines on the page. At the end of each line in the key, there is either a number or a name referring to a couplet. An example of the bracket key is given below, in which all the same seven

Page 3 of 14 genera of Ranunculaceae (i.e. Ranunculus, Adonis, Anemone, Clematis, Caltha, Delphinum, Aquilegia. are identified: The indented or yoked Key for the taxa under consideration is shown below. 1. Plants woody…………………………………………………………...4. Clematis

1. Plants herbaceous……………………………………………………………(2) 2. Calyx and corolla differentiate………………………………………………(3)

2. Calyx and corolla not differentiated…………………………………………(4) 3. Petals with nectary at base…………………………………………….1. Ranunculus 3. Petals without nectary at base ………………………………………...2. Adonis 4. Fruit achene……………………………………………………………3. Anemone 4. Fruit follicle ………………………………………………………………. (5) 5. Spur present………………………………………………………………….(6) 5. Spur absent………………………………………………...... 5. Caltha 6. No. of spurs 1…………………………………………………………6. Delphinium 6. No of spurs 5…………………………………………...... 7. Aquilegia

Multi-access keys or Polyclaves: In a polyclave method of identification the user of the system is free to choose any character, in any order or sequence, and thus avoid the rigid format of traditional dichotomous keys. Eventually it is the user who decides the sequence in which to use the characters, and even if the information about a few characters is not available, the user can go ahead with identification. Identification may often be achieved without having to use all characters available to the user. Such identification methods often make use of cards. Two basic types of cards are in use. Body punched cards: The cards are also named window cards or peek-a-boo cards and make use of cards with appropriate holes in the body of the card. The process involves using one card for one attribute. In our example we shall need 11 cards. Numbers are printed on the cards corresponding to the taxa for which the identification key is meant. In our example, we use only 7 of these numbers corresponding to our 7 genera. On each card, holes are punched corresponding to the taxa in which that attribute is present. In our example card “Habit woody” will have only one hole at number 4 (genus Clematis), and the card “Habit herbaceous” will have holes at 1,2,3,5,6,7. Once the holes are punched at appropriate positions in all the cards, we are ready for identification. The user studies the unknown plant and makes a list of characters, according to the sequence he wishes and the characters that are available to him. The user starts the identification process by picking up the first card concerning the first attribute in his list of attributes of the unknown plant. He next picks up the second card concerning the second attribute from his list and places it over the first one. This will close some holes of first card and some of the second. Only those holes will remain open which correspond to the taxa which contain both the attributes. The third card is subsequently placed over second card and the process is repeated with additional cards until finally only one hole is visible through the pack of selected cards. The taxon to which this hole corresponds is the identification of the unknown plant.

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4 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50

Figure: A body- punched card for herbaceous habit for the representative genera of Ranunculaceae: 1. Ranunculus, 2. Adonis, 3. Anemone, 4. Clematis, 5. Caltha, 6. Delphenium, 7. Aquilegia.

Edge Punched Cards:

An edge punched card differs from the body punched card in that there is one card for each taxon and holes are punched all along the edge of the card, one for each attribute. In our example here, we shall need seven cards, one for each genus. The holes are normally closed along the edge. For each attribute, present in the taxon, the hole is clipped put to form an open notch instead of circular hole along the edge.

For actual identification, all cards are held together as a pack. A needle is inserted in the hole corresponding to the first attribute of the unknown plant. As this needle is lifted up the taxa containing this attribute would fall down, and those lacking that attribute would remain in the pack lifted by the needle. The latter are rejected. The cards falling down are again arranged in a pack, the needle inserted in the hole corresponding to the next attribute of the unknown plant. The process is repeated until finally a single card falls down. The Taxon, which this card represents, is the identification of the unknown plant.

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Plant taxanomic evidence from Cytology: According to Solberg (1968) and Stebbins (1971) the chromosomes have been used in resolving many taxonomic problems. Utilization of characters and phenomenon of cytology for explanation of taxonomic problems is also known as cytotaxonomy. Three types of chromosomal information have been of significance in systematics. 1. Chromosome number 2. Chromosome structure 4. Chromosome behaviour during meiosis 1. Chromosome Number The number of chromosomes in a species is usually constant and this makes it an important taxonomic character. However, there are exceptions where chromosome changes usually occur in chromosomes during the process of division, and these changes may affect the gene sequence, their number or even there may be loss of chromosomes themselves. The continuity of this slow process, results in the evolution of new chromosomal races. The chromosome number shows a wide range in vascular plants. The lowest chromosome number in flowering plants is recorded in Haplopappus gracilis (Asteraceae) [2n = 4] and the highest in Poa litorosa (Poaceae) [2n = 265]. Ophioglossum species (Pteridophyte) has the highest number of chromosomes in the plant kingdom (2n = 1240). This great diversity of chromosome numbers and their relative constancy within populations and species provide an important character for taxonomic groupings of large number of plants. Examples: i). The two genera Thallictrum and Aquilegia – originally place in two separate Sub families by Hutchinson 1959,1973 are distinct in having small chromosomes (and x=7) and as such have been separated into a distinct Subfamilies Thalictroideae of family Ranunculaceae ii). In family Poaceae. Similarly, subfamilies have been raised Bambusoideae with basic chromosome number (x =12) Pooideae with basic chromosome number (x=7). iii). Spartina for long placed in the tribe Chlorideae (x = 10) although its chromosomes (x = 7) were at variance. Merchant (1968) showed the genus to have, infact x =10, thus securing placement within Chlorideae. iv). The duplication of chromosome numbers leading to polyploidy may prove to be of taxonomic significance. The grass genus Vulpia contains diploid (2n = 14), tetraploid (2n = 28), and hexaploidy (2n = 42), species. The genus is divided into five sections. It is presumed that tetraploid and hexaploidy species of Vulpia arose from diploid progenitors. v). The Autopolyploid developed from the diploid species may show minor differences from the diploid species and is rarely recognised as an independent entity, but the allopolyploids with distinct characteristics may be recognized as an independent species. 2. Chromosome structure: Chromosomes show considerable variation in size, position of centromere and position of secondary constriction. The structure of the chromosome set (genome) in a species is termed Karyotype and is commonly diagrammatically represented in the form of an ideogram or Karyogram. An analysis of a large number of studies has led to the conclusion that a symmetrical Karyotype (chromosomes

Page 6 of 14 essentially similar and metacentric) is primitive and an asymmetric karyotype (different types of chromosomes in a genome) advanced. Examples: i). The genera Agave and Yucca formerly placed in families Agavaceae and Liliaceae respectively have been shifted and brought into Agavaceae on the basis of distinctive bimodal karyotype of Agavaceae consisting of 5 large chromosomes and 25 small ones. ii). By Giemsa banding patterns and Silver staining studies it was concluded that some chromosomes of top onion resemble A. cepa and other resemble A. fistulosum, of the two satellites one resembles either species. Top onion is as such a pseudodiploid with no homologous chromosomes. The study confirmed that top onion is a hybrid between the two aforesaid parents A. cepa and A. fistulosum and thus would be better known as A. cepa x A. fistulosum and not as a variety of either species . 3. Chromosome behaviour during meiosis. The meiotic behaviour of chromosomes enables comparison between genomes to detect the degree of homology especially when they are a result of hybridization. A greater degree of genomic non homology results in either failure of pairing (a synapsis) or a loose pairing chromosome without chiasmata so that the chromosomes fall apart before metaphase (desynapsis). In extreme cases the entire genome may fail to pair. The genome analysis of suspected hybrids has helped in establishing the percentage of several polyploid species. A diploid hybrid between two species exhibits failure of meiotic pairing due to non-homology of genomes resulting in hybrid sterility, but when hybridization is followed by duplication of chromosomes form a tetraploid hybrid which is fertile. A triploid hybrid is also sterile but its hexaploidy is fertile. Genomic analysis has confirmed that the hexaploidy Senecio cambrensis is allohexaploid between tetraplod S. vulgaris and diploid S. squalidus. Similarly, the tetraploid Tragopogan mirus is the result of hyrbridation between the two diploid species T. dubius and T. porrifolius. The most significant case however is the common bread wheat Triticum aestivum. A genomic analyses have confirmed that genome is derived from diploid T. monococcum and from Aegilops speltoides and from diploid Aegilops tauscchii

Plant Taxanomic evidence from Phytochemistry (Chemotaxonomy): Chemotaxonomy utilizes chemical information to improve upon the classification of plants. A large variety of chemical compounds are found in plants and quite often the biosynthetic pathways producing these compounds differ in various plant groups. In many instances the biosynthetic pathways correspond well with existing schemes of classification based on morphology. In other cases, the results are at variance, thus calling for revision of such schemes. The natural chemical constituents are conveniently divided as under. 1. Micromolecules: compounds with low molecular weight (less than 1000). These are of two types. I). Primary metabolites: II). Secondary metabolites: 2. Macromolecules: Compounds with high molecular weight (000 or more): These are of two types 1). Sementides: are information carrying molecules DNA, RNA and proteins. 2). Non-sementide macromolecules: Compounds not involved in information transfer like starches, cellulose etc.

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I). Primary metabolites: These compounds are involved in vital metabolic pathways. Most of them are universal in plants eg. citric acid and aconotic acid participate in krebs cycle and are present is all aerobic organisms. In Gilgiochloa indurate (Poaceae), alanine is the main amino acid in leaf extracts, proline in seed extracts and asparagine in flower extracts. Rosaceae is similarly rich in arginine. II). Secondary metabolites: compounds which are the bi products of metabolism and have been found to play role in defence against predators, pathogens, allelopathic agents, and also help in pollination and dispersal. The following major categories of secondary metabolites are of taxonomic significance i). Non protein aminoacids: Their distribution is not universal but specific to certain groups eg. Lathyrine is only known from Lathyrus. Canavanine occurs only in Fabaceae. ii). Phenolics: These are widely distributed in plant kingdom eg. Catechol, hydroquinone Phloroglucinol and pyragallol. The crushed leaves of of Anthoxanthum odoratum is identified by the characteristic smell of phenolic coumarin. More than 300 coumarins have been found in nearly 80 families. iii). Lignin: It is a branched polymer of three simple phenolic alcohols, but in gymnosperms it is composed of coniferyl alcohol sub units and in angiosperms it is composed of coniferyl and Sinapyl alcohol subunits.

iv). Flavonoids: These are composed of two benzene rings joined by a C3 open or closed structure. Common examples are v). Anthocyanins and Anthoxanthins: are important pigments in the cell sap of petals providing red and blue (Anthocyanins) and yellow (Anthoxanthins) colours in a large number of in a large number of families of angiosperms. These pigments are absent in Caryophyllales in which these are replaced by highly different compounds betacyanins and betaxanthins together called as betalains. vi). Alkaloids: These are organic nitrogen containing bases with a heterocyclic ring of some kind. Their distribution is restricted to some 20% of angiosperms. They are present in storage tissues, seeds, fruits and roots. They are synthesized from aminoacids like tyrosine, tryptophan, , ornithine, arginine, and lysine. Tobacoo alkaloid Nicotene is synthesized from nicotinic acid, and caffeine from purine, morphine, codeine, and papaverine are found in opium poppy. Conalium is found in Conium maculatum. Alkaloids are more widely distributed in dicots as compared to monocots.Tropane alkaloids of Solanaceae, and Convolvulaceae are similar suggesting a close relationship. The families are placed in the same order in recent systems. Papaveraceae earlier grouped Cruciferae and caparaceae is now removed to nearer Ranunculaceaeon the basis of the absence of glucosinolates and presence of benzylisoquinone. vii). Glucosinolates: These are sulphur containing compounds found in 15 families of angiosperms, mainly concentrated in the order caparales. Originally Cruciferae, Capparaceae, Papaveraceae and Fumariaceae were placed in same order Rhoeadales. Chemical and other evidence however, supported the placement of Cruciferae and Capparaceae in order capparales on the basis of presence of Glucosinolates. Papaveraceae and Fumariaceae in the order Papaverales on the basis of absence of Glucosinolates. Viii). Cyanogenic glycosides: are phytotoxins which occur atleast in 2000 plant species. There are approximately 25 cyanogenic glycosides known. The major cyanogenic glycosides found in the edible plant parts include. Most of the cyanogenic glycosides are widely spread others such as cyclopentenoid cyanogenic glycosides are restricted in distribution mainly to Flacourticaceae,

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Passifloraceae, Turneraceae and Malesherbiaceae. Leucine derived cyanogenic glycosides are found in Rosaceae, Fabaceae and Sapindaceae. Several families belonging to Magnoliaceae and Lauralesb contain Cyanogenic glycosides derived from tyrosine. ix). Terpenes: include a large group of compounds derived from the mevalonic acid precursor and are mostly polymerized isoprene derivatives. Common examples are Camphor (Cinnamomum) Menthol (Mentha) and Carotenoids. These have been largely used in distinguishing specific and subspecific entities, geographic races and detection of races. Examples: 1. Studies in citrus have focused on determination of the origin of certain cultivars. 2. Studies on juniperus viginiana and J. ashei have refuted previous hypothesis about extensive about extensive hybridization between the two species. 3. The tribes in the family compositae are characterized by distinct types of sesquiterpene lactones they produce. Triterpenoids: group of terpenes occur in Apiaceae and Pittosporaceae support their close relationship. Iridoids: This is another group of terpenes. The occurrence of a distinctive iridoid aucubin in Budleja has been taken to support its transfer from Loganiaceae to Budlejaceae.

2. Macromolecules: Compounds with high molecular weight (000 or more): These are 1). Sementides: are information carrying molecules DNA, RNA and proteins. These are popular sources of taxonomic information and most of this information comes from proteins. The techniques used for the separation study and comparison are serological and electrophoretic. The techniques have placed a good role in the taxonomy Examples: It has been established the distinct identity of Bromus pseudosecalinus previously recognized as a variety of B. secalinus . The same studies have also supported the removal of Nelumbo from Nymphaeaceae in to the separate family Nelumbonaceae. Placement of Hydrastis in Ranunculaceae and not Berberidaceae. Electrophoretic studies have supported the origin of hexaploidy wheat (Tritium aestivum) from Aegilops tauschii and T. dicoccum Amino acid sequencing has pointed to the merger of Aegilops with triticum. 2). Non-sementide macromolecules: Compounds not involved in information transfer like starches, cellulose etc. do not play any role in taxonomical evidances.

Plant Taxonomic Evidences from Molecular Data: Molecular systematic involves the use of DNA and RNA to infer relationship among organisms. Molecular data reflect more likely true phylogeny than morphological data, because they reflect gene level changes, which are less subject to convergence. In many cases molecular data have allowed the placement of taxa whose relationship were known to be problematic. Plant cell contain three different genomes of the chloroplast, mitochordon, and the nucleus. Systematists use data from all the three genomes. Molecular phylogenetics is done by using either genome rearrangements or sequence of DNA. Nuclear DNA: The early studies on utilisation of nucleic acids in taxonomy involved DNA/DNA hybridisation using the whole DNA for study. In a method developed by Bolton and Mecarthy

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(1962) extracted DNA is so treated that it converts into a single stranded polynucleotide chain. The DNA of another organism is similarly made single stranded. The two are subsequently allowed to hybridize invitro. The degree of reassociation (annealing) expresses the degree of similarity in sequences of nucleotides of the two organisms. Bolton (1966) found that only half nucleotide sequence in the DNA of Vicia villosa are homologous with those of Pisum, while only 1/5th are homologous between Phaseolus and Pisum. In the technique of DNA/RNA hybridisation the RNA is hybridised with the complementary DNA of related plants. Mabry (1976) used this technique in Centrospermae is quite close to betalain-containing families, but not as close as the later are to each other. The nucleotide sequence of 18SRNA and 26SRNA of ribosomes have been found to be useful in distinguish phylogenetic groups. There has been considerable advancement in recent years. It is now possible to break (cleave) DNA at highly specific points using restriction endonucleases, each of which can cleave DNA at a highly specific recognition site, thus producing highly characteristic restriction fragments of DNA. These fragments can be separated by electrophoresis and hybridised with radioactive single-stranded DNA or RNA probes. The method has been used with encouraging results in Atriplex, Secale and several other genera. Belford and Thomson (1979) using side-copy sequence hybridization in Atriplex concluded that division into two subgenera in this genus is not correct. The DNA based molecular markers are applied in various aspects of taxonomy to analyse: (i) Genetic identity. (ii) Genetic relatedness among populations, geographic populations and species. (iii) Pedigree. (iv) Differentiation among isolated species. (v) Phylogenetic structure at various micro and macro levels. A number of molecular parameters are useful in carrying out phylogenetic and systematic studies. Of the various molecular approaches, the PCR based technology offers maximum potential for genetic analysis, phylogenetics and systematics. Taxonomists have realized power of MAAP markers is recording taxonomic ambiguities. Examples:

Eight species of Atriplex of Chenopodiaceae were compared on the basis of their DNA nucleotide sequences. DNA of wheat, rye and barley of Triticaceae, compared with that of oat of Aveneae showed marked differences. Moreover, wheat DNA is more similar to the DNA of rye than that of barley.

Mitochondrial DNA: Mitochondrial DNA has been studies from several species of plants. Each mitochondrion contains several copies of mtDNA and each cell contains many mitochondria. The number of mtDNA molecules per cell could be very large. Most mtDNA are circular but linear in Chlamydomonas reinhardtii. mtDNA is considerably larger, containing many non-coding sequences The physical mapping of genes in vascular plants has shown that these are located in different positions on mtDNA circles of different species, even in fairly closely-related species. This renders mtDNA less useful in phylogenetic studies.

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Chloroplast DNA: cp DNA can be easily isolated and analyzed. The DNA of chloroplast is highly conserved type. The cp DNA circular molecule with 2 regions in opposite direction encoding same genes are called inverted repeats. Between inverted repeats single copy regions are present. In all cp DNA same set of genome are found but arranged differently in different species. The genes present in cp DNA include genes for r-RNA, t-RNA, ribosomal proteins and about 100 different polypeptides and subunits of enzyme coupling CO2. The important gene on cp DNA is rbcL encoding large subunit of photosynthetic enzyme i.e., RUBISCO. This gene is not found in parasites. It is a long gene consisting of 1428 bp. Taxonomic hierarchy: It is defined as the orderly arrangement of organisms into successive levels of the biological classification from kingdom to species. Each of the level is called as the taxonomic category or rank. There are seven levels of taxonomic hierarchy: 1. Kingdom, 2. Phylum/Division 3. Class 4.Order 5. Family 6. Genus 7. Species These are called obligate categories. Taxonomic groups, categories and ranks These are inseparable once a hierarchical classification has been achieved. Rosa alba is thus nothing else but a species and Rosa is nothing other than a genus, however the difference do exit in concept and application. The categories are like shelves of an Almirah, having no significance when empty and importance and meaning only after something has been placed in them. Thereafter, the shelves will be known by their contents, books, toys, clothes, shoes etc. Categories in that sense are artificial and subjective and have no basis in reality they correspond to nothing in nature. However, they have a fixed position in hierarchy in relation to other categories. But once a group has been assigned to a particular category the two are inseparable and the category gets a definite meaning because it now includes something actually occurring in nature. The word genus does not carry a specific meaning but a genus Rosa says a lot. We are now talking about roses. There is particularly no difference between category and rank expect in the grammatical sense. Rosa thus belongs to the category genus and has generic rank. If categories are like shelves ranks are like partitions, each separating the given category from the category above. Taxonomic groups on the other hand are objective and non- arbitrary to the extent that they represent discrete sets of organisms in the nature. Groups are biological entities or a collection of such entities. By assigning them to the category providing an appropriate ending to the name Rosaceae ending aceae signifies a family which among others also includes Roses belonging to genus Rosa. we establish the position of taxonomic groups in the hierarchal system of classification. Some important characters which enable a better understanding of the hierarchical system of classification are enumerated below. 1. Different categories of the hierarchy are higher or lower according to whether they are occupied by more inclusive or less inclusive groups than those occupying lower categories. 2.Plants are not classified into categories but into groups. It is important to note that a plant may be a member of several taxonomic groups each of which is assigned to a taxonomic category. But is not

Page 11 of 14 itself a member of any taxonomic category. A plant collected from the field may be identified as Poa annua (Assigned to species Category) It is the member of Poa (assigned to genus category) and so on, but the plant can not be said to be belonging to the species category . 3. A Taxon may belong to other taxa, but it can be a member of only one category Urticadioica , thus is a member of Urtica, Urticaceae, Urticales and so on. But it belongs to species category. 4. Categories are not made up of lower categories. The category family is not made of genus category since there is only one genus category. 5. The characters shared by all members of a taxon placed in a lower provide the characters for the taxon immediately above. Thus, the characters shared by all the species of Brassica make up the characters of the genus Brassica. The characters shared by Brassica and several other genera form for distinguishing of the family Brasicaceae . It is important to note that the higher a group is placed in the hierarchy, the fewer will be the characters shared by the subordinate units. Many higher taxa as such (e.g. Dicots: Magnoliosida) can only be separated by a combination of characters, no single diagnostic character may distinguish the taxa. Dicots are thus conveniently separated from monocots by possession of two cotyledons, pentamerous flowers, reticulate venation and vascular bundles in the ring as against one cotyledon, trimerous flowers, parallel venation, and scattered vascular bundles in monocots, but when taken individually, Smilax is a monocot with reticulate venation and plantago is a dicot with parallel venation. Similarly, Nymphaea is the dicot with scattered bundles and the flowers are trimerous in Phyllanthus which is a dicot. Botanical Nomenclature: The system of naming objects of biological origin is called as nomenclature. Man has been interested in plants since prehistoric times and in all nations, names have been given to plants in their own language. The local names would vary from place to place, even within a country. It is thus clear that no plants can be identified on the basis of local name in different regions of a country. Hence, there is a need to standardise the naming of a plant in such a way that it may not be difficult to identify it in any part of the world. This necessitated the need for assigning scientific names to plants.

Need for scientific names Scientific names are preferred over vernacular names since the later pose a number of problems: 1. Vernacular names are not available for all the species known to man. 2. Common names are restricted in usage and are applicable in one or a few languages only. They are not universal in application. 3. A single name is often used for two or more species e.g. “touch me not” is the name for both Impatiens balsamifera (Balsam) and Mimosa pudica (sensitive plant). 4. Vernacular names usually do not provide information indicating family or generic relationship.

Binomial System of nomenclature: The earliest botanical names were polynomials, composed of several words. For example, A species of willow was named Salix pumila angustifolia altera by Clusius in his herbal (1583) Casper Bauhin, (1623) introduced the concept of Binomial nomenclature in his book ‘Pinax Theatre Botanica’. Carolous Linnaeus, 1753 firmly established this system of naming in his ‘Species Plantarum’. According to the binomial system of nomenclature, the name of a plant consists of two Latin or Latinised words, the first (generic) representing the genus and the second (specific epithet) the

Page 12 of 14 species. For example, the botanical name of potato is Solanum tuberosum. Solanum (Generic name) tuberosum (Specific name). The early rules of nomenclature were set forth by Linnaeus in his Critica botanica (1737). The following rules are followed for Botanical Nomenclature as given below:

1. The generic name starts with a capital letter, whereas the specific name with a small letter. 2. The scientific names should be either underlined in case of hand written or italicised if printed. 3. Name of the scientist (who proposed name) should be written in short after the specific name e.g. Mangifera indica Linn. 4. If any scientist has proposed wrong name then his name should be written in bracket and the scientist who corrected the name should be written after the bracket. e.g., Tsuga Canadensis (Linn.) Salisbury 5. Scientific names should be derived from Latin or Greek languages because they are dead languages. 6. In Botanical Nomenclature tautonyms are not valid.

Principles of ICBN: The Principles constitute the basis of botanical nomenclature which are as under: 1. Botanical nomenclature is independent of Zoological and Bacteriological nomenclature. 2. The application of names of taxonomic groups (taxa) is determined by means of nomenclature types. 3. The Nomenclature of the taxonomic groups is based upon priority of publication. 4. Each taxonomic group can bear only one correct name, the earliest that is in accordance with the rules, except in specific cases. 5. Scientific names of taxonomic groups are treated as Latin regardless of their derivation. 6. The rules of nomenclature are retroactive unless expressly limited.

RULES: The rules give detailed prescriptions on all the points connected with the naming of plants. Some of the important rules are as under: 1. Ranks of Taxa:- The term taxa (singular taxon) means, Taxonomic group of any rank‟. Here the rank of a species is taken as basis. The relative order of the ranks of taxa are; species, genus, tribe, family, order, class, division and kingdom. A species is divided into subspecies, sub-species into varieties, variety into sub-varieties, sub-variety into forma and forma into clone. 2. Typification: The names of different taxonomic groups are based on the type method, by which a certain representative of the group is the source of the name for the group. This representative is called the nomenclature type or simply the type, and methodology as typification. The code recognises several kinds of types, depending on the way in which a type specimen is selected. These included: I). Holotype: A particular specimen or illustration designated by the author of the species to represent type of a species.

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II). Isotype: A specimen which is a duplicate of holotype, collected from the same place, at the same time and by the same person. III). Syntype: Any one of the two or more specimens cited by the author when no holotype was designated is called syntype. IV). Paratype: The specimen cited in the original description other than the holotype is paratype. V). Lectotype: It is the specimen selected from the original material to serve as the nomenclatural type if the holotype was not designated or missing. A lectotype is selected from isotypes or syntypes. If no isotype or syntype is extant , the lectotype must be chosen from among the paratypes if such exist. VI). Neotype: It is the specimen selected to serve as a nomenclature type of a taxon when all the original material is missing. VII). Cotype: it is the second specimen collected from the same plant from which the holotype was collected. VIII). Topotype: it is a specimen collected from the same locality from where the holotype was collected. IX). Epitype: A specimen or illustration selected to serve as an interpretative type when the holotype, lectotype or previously designated neotype, or all original material associated with the validity published name, is demonstrably ambiguous and cannot be critically identified for purposes of the precise application of the name of a taxon 3. Principle of Priority: The Principle of Priority is concerned with the selection of the single correct name for a taxonomic group. After identifying legitimate and illegitimate names, and rejecting the latter a correct name has to be selected from among the legitimate ones. If more than one legitimate names are available for the taxon, the correct name is the earliest legitimate name in the same rank, proposed just after 1 May, 1753- the date of publication of Linnaeous Species Plantarum. Example: The three commonly known binomials for the same species of Nymphaea are N. nouchali Burm.f.,1768, N. acutiloba Dc.,1824, N. stellate Willd.,1799 and N. malabarica Poir., 1798. Using the priority criterion, N. nouchali Burm.f., is selected as the correct name as it bears the earliest date of publication. The other three name as names are regarded as synonyms. Name of Families: A family name is formed by adding the suffix-aceae to the stem of legitimate name of an included genus, e.g., Rosaceae from (Rosa) and Cucurbitaceae from (Cucurbita). Some family names which do not follow this rule were, therefore, changed. However, the old names are also conserved due to their long use. Compositae ------→ Asteraceae Palmae ------→ Arecaceae Cruciferae ------→ Brassicaceae Leguminaceae ------→ Fabaceae Gramineae ------→ Poacea Labiatae ------→ Lamiacea Guttiferae ------→ Clusiaceae Umbelliferae ------→ Apiacea

Author Citation: The name of a taxon is incomplete unless the name of the author or authors who first validly published the name, is cited along with it. The names of the authors are commonly abbreviated, e.g., Linn. or L. For Carolous Linnaeus, Benth. for G. Benthem.

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Sigle author: The name of a single author follows the name of a species, e.g. Solanum nigrum L. Multiple authors: The names of two or more authors may be associated with a name for a variety of reasons. These different situations are exhibited by citing the name of the authors differently. 1. Use of et. When two or more authors published a new species or propose a new name, their names are linked by et, e.g. Delphinium viscosum Hook.f. et Thomson 2. Use of et al: When more than three authors are involved, citation is normally restricted to first author and is followed by et al. 3. Use of parenthesis: If a genus or taxon of lower rank is altered in rank or position, but retains its name or epithet, the name of the author who first published the name (basionym) must be cited in parenthesis followed by the name of the author who effected the change. This is called double citation, e.g., Cynodon dactylon (Linn.) Pers., based on the basionym Panicum dactylon Linn. 4. Use of ex: The names of two authors are linked by ‘ex’ when the first author has proposed a name but was validly published only by the second author, e.g. Cerasus cornuta Wall.ex Royle 5. Use of in: The names of authors are linked using ‘in’ when the first author published a new species or a name in a publication of another author e.g. Carex kashmirensis Clarke in Hook .f. Clarke published this new species in the flora of British India whose author was Sir J. D. Hooker. 6. Use of emend: The names of two authors are linked using emend (emendavit: person making the correction) when the second author makes some changes in the diagnosis or in circums cription of a taxon without altering the type, e.g. Phyllanthus Linn. Emend. Mull 7. Use of square brackets: Square brackets are used to indicate prestarting point author. The generic name Lupinus was effectively published by Tournefort in 1719, but as it happens to the earlier than 1753, the starting date for botanical nomenclature based on Species plantarum of Linnaeus, the appropriate citation for the genus is Lupinus [Tourne] L Valid Publication: The new name of a taxon is considered valid or effective for publication, only when it is distributed in a printed form to the general public or atleast to ten well established botanical institutions with libraries accessible to botanists generally. A valid publication should satisfy the following requirements: 1. Formulation: A name should be properly formulated and its nature indicated by a proper abbreviation after the name of the author: (i) sp. nov. for species nova, a species new to science. (ii) comb. nov. for combination nova, a name change involving the epithet of the basionym, name of the original author being kept within parenthesis. 2. Latin diagnosis: Names of all new species published 01-01-1953 onwards should have a Latin diagnosis. Full description of the species in any language can accompany the Latin diagnosis. 3. Typication: A holotype should be designated. Publication on or after 01-01-1958 of the name of a taxon of the Rank of genus or below is valid only when the type of the name is indicated.