Biyani's Think Tank Taxonomy and Embryology of Angiosperm B.Sc

Biyani's Think Tank Concept based notes Taxonomy and Embryology of Angiosperm B.Sc. Part-III

Dr Ruby

Deptt. of Scienge

Biyani Girls College, Jaipur

Published by :

Think Tanks

Biyani Group of Colleges

Concept & Copyright :

Biyani Shikshan Samiti

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E-mail : [email protected]

Website :www.gurukpo.com; www.biyanicolleges.org

Edition : 2012

While every effort is taken to avoid errors or omissions in this Publication, any mistake or omission that may have crept in is not intentional. It may be taken note of that neither the publisher nor the author will be responsible for any damage or loss of any kind arising to anyone in any manner on account of such errors and omissions.

Leaser Type Setted by :

Biyani College Printing Department

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Taxonomy and Ebbryology 3

Preface

I am glad to present this book, especially designed to serve the needs of the students. The book has been written keeping in mind the general weakness in understanding the fundamental concepts of the topics. The book is self-explanatory and adopts the “Teach Yourself” style. It is based on question-answer pattern. The language of book is quite easy and understandable based on scientific approach.

Any further improvement in the contents of the book by making corrections, omission and inclusion is keen to be achieved based on suggestions from the readers for which the author shall be obliged.

I acknowledge special thanks to Mr. Rajeev Biyani, Chairman & Dr. Sanjay Biyani, Director (Acad.) Biyani Group of Colleges, who are the backbones and main concept provider and also have been constant source of motivation throughout this endeavour. They played an active role in coordinating the various stages of this endeavour and spearheaded the publishing work.

I look forward to receiving valuable suggestions from professors of various educational institutions, other faculty members and students for improvement of the quality of the book. The reader may feel free to send in their comments and suggestions to the under mentioned address.

Author

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Section-A

Taxonomy

Q.1 Classification of Angiosperm with special reference of Linnaeus, Bantham and Hooker?

Ans. ANGIOSPERM CLASSIFICATION

The classification of angiosperms is still very controversial, and two schemes are presented here – the first (B&H) as a means to LEARNING the families, the second (APG) as a presentation of the rudiments of an agreed EVOL UTIONARY TREE. Historically a number of schemes have been produced. Bentham & Hooker's Genera Plantarum (1862-1883) – comprising 200 families and 7,569 genera – pre-dated the publication of Charles Darwin‘s Origin of Species, so this is essentially a non-evol utionary scheme. However, the arrangement of families was based on characters which provided a sequence fr om what they took as the most primitive to the most derived families – the Scalae Naturae.

The classification was based on few, essential characters, and as a result is highly predictive – examination of these characters will place an unknown specimen into a particular category. The Angiosperm Phylogeny Group (APG): Systematic research over the past 150 years has changed our view of plant classification, especially in the last 10 years, when major advances in DNA sequencing have provided a completely new ave nue of approach. Numerous classifications and schemes have been published: Hutchinson (328 families), Cronquist (388), Takhtajan (592) Dahlgren (477), Thorne (454) Brummitt (445), and Reveal (612), each differ in the recognition of families and the overall scheme. As a result, fam ilies, orders and sub-classes are not comparable between any of these systems. Molecular studies are by no means final, and, contrary to what many reference books and journals might imply, a modern synthesis is far from stabilised. However, a consensus is now beginning to emerge. The combin ed work of many scientists under an umbrella grouping known as the Angiosperm Phylogeny Group (APG) has produced the rudiments of an agreed evolutionary tree.

Bentham and Hooker

George Bentham and Joseph Dalton Hooker - Two English taxonomists who were closely associated with the Royal Botanical Garden at Kew, England have given a detailed classification of plant kingdom, particularly the angiosperms.

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Taxonomy and Ebbryology 5

Fig. - Taxonomists: Bentham and Hooker

They gave an outstanding system of classification of phanerogams in their Genera Plantarum which was published in three volumes between the years 1862 to 1883. It is a natural system of classification. However, it does not show the evolutionary relationship between different groups of plants, in the strict sense. Nevertheless, it is the most popular system of classification particularly for angiosperms. The popularity comes from the face that very clear key characters have been listed for each of the families. These key characters enable the students of taxonomy to easily identify and assign any angiosperm plant to its family.

Bentham and Hooker have grouped advanced, seed bearing plants into a major division called Phanerogamia. This division has been divided into three classes namely:

1. Dicotyledonae

2. Gymnospermae and

3. Monocotyledoneae

1 Class :Dicotyledonae

This group includes angiosperms in which the seed bears two cotyledons and leaves exhibit reticulate venation. It is divided into three subclasses - Polypetalae, Gamopetalae and Metachlamydae.

Sub-class Polypetalae

The flowers contain distinct non-essential whorls calyx and corolla. In the corolla petals are free. This sub-class includes 8 series Thalamiflorae, Disciflorae and Calyciflorae.

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Series Thalamiflorae: Many stamens in the androecium. Flower is hypogynous.

Series Disciflorae: Hypogynous flowers with a cushion-like disc around or below the ovary.

Series Calyciflorae: Flowers epigynous or perigynous. Thalamus is in the form of a cup.

Sub-class Gamopetalae Flowers with distinct calyx and corolla. In the corolla petals are fused. This sub- class includes 3 series.

Series Inferae: Flowers with inferior ovary.

Series Heteromerae: Flowers with superior ovary. Number of carpels - more than two.

Series Bicarpellatae: Flowers with superior ovary. Number of carpels - two.

Sub-class Monochlamydae

The flowers are with only one non-essential whorl (perianth) or absence of non- essential whorls. It includes 8 series.

Curvembryae: Usually single ovule, embryo coiled around the endosperm.

Multiovulate Aquaticae: Aquatic plants with syncarpous ovary and many ovules.

Multiovulate Terrestris: Terrestrial plants with syncarpous ovary and many ovules.

Microembryae: Only one ovule, small, tiny embryo endospermic seed.

Daphnales: Only one carpel and single ovule.

Achlamydosporae: Ovary inferior, 1 to 3 ovules - unilocular.

Unisexuales: Flower unisexual, perianth usually absent.

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Taxonomy and Ebbryology 7

Ordines Anomali: (Anomolous families) Plants with uncertain systematic position but closer to unisexuales.

2 Class : Gymnospermae

This group includes the gymnosperms in which seeds are not enclosed in fruits. This class is divided into three families Gnetaceae, Confiraceae and Cycadaceae.

Fig. - Angiosperm Classification

3 Class: Monocotyledonae

This group includes angiosperms in which the seed bears only one cotyledon. The leaves exhibit parallel venation. It is divided into the following seven series.

Microspermae: Ovary is inferior, seeds are minute and non-endospermic.

Epigynae: Ovary inferior, seeds are large and endospermic.

Coronarieae: Ovary superior, perianth petalloid.

Calycinae: Ovary superior, perianth sepalloid.

Nudiflorae: Perianth reduced or absent. Seeds are endospermic.

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Apocarpae: Carpels more than one, free, seeds are endospermic.

Glumaceae: Perianth reduced or absent, scaly bracts present.

Each of the series mentioned under dicotyledonae and monocotyledonae have been further divided into orders and families. Bentham and Hooker classified the angiosperms into 202 families. They were able to provide distinct diagnostic key characters to each of these families. This is the reason for the popularity of Bentham and Hooker's classification particularly amongst the taxonomists

Microspermae: Ovary is inferior, seeds are minute and non-endospermic.

Epigynae: Ovary inferior, seeds are large and endospermic.

Coronarieae: Ovary superior, perianth petalloid.

Calycinae: Ovary superior, perianth sepalloid.

Nudiflorae: Perianth reduced or absent. Seeds are endospermic.

Apocarpae: Carpels more than one, free, seeds are endospermic.

Glumaceae: Perianth reduced or absent, scaly bracts present.

Q.2 Explain concept of Binominal Nomenclature and its advantage? Ans. Binomial nomenclature (also called binominal nomenclature or binary nomenclature) is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name (which may be shortened to just "binomial"), a binomenal or a scientific name; more informally it is also called a Latin name. The formal system of naming species of living things is called binomial nomenclature (especially in botany, but also used by zoologists), binominal nomenclature (since 1953 the technically correct form in zoology), or binary

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Taxonomy and Ebbryology 9

nomenclature. This system of naming was invented byLinnaeus. The up-to-date version of the rules of naming for animals and plants are laid out in the International Code of Zoological Nomenclature and the International Code of Botanical Nomenclature respectively.

The first part of the name identifies the genus to which the species belongs; the second part identifies the species within the genus. For example, humans belong to the genus Homo and within this genus to the species Homo sapiens. The introduction of this system of naming species is credited to Linnaeus, effectively beginning with his work Species Plantarum in 1753.

The application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Nomenclature for algae, fungi, and plants (ICN) for plants. Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules.

In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not, even when derived from a proper noun such as the name of a person or place. Similarly, both parts are italicized when a binomial name occurs in normal text. Thus the binomial name of the annual phlox is now written as Phlox drummondii.

The name "Linnaeus" tells the reader who it was that named the species; 1758 is the date of the publication in which the original description can be found, in this case the 10th edition of the book Systema Naturae. (Botanists are not required to give the date).

Many scientific names describe some characteristic of the organism (alba=white; rubra=red); many are derived from the name of the discoverer or the geographic location of the organism. Genus and species names are always italicized when printed; the names of other taxa (families, etc.) are not.

When a species (or several species of the same genus) is mentioned repeatedly, the genus may be abbreviated after its first mention, as in Q. alba. Subspecies are indicated by a trinomial; for example, the southern bald eagle is Haliaeetus leucocephalus leucocephalus, as distinguished from the northern bald eagle, H. leucocephalus washingtoniensis.

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How To Write Plant Species Names (Binomial Nomenclature Or Scientific Names)

1. As many of you know, common names may be the same for many different plant species. For example, many of the species in the Opuntia genus (contains several species) share Prickly Pear Cactus as their common name. So how do we name all of the plants and what is a genus?

2. We use the binomial naming system (scientific name), as the name implies, uses two words to name a particular species.

The first word we use to describe a plant is the generic name (genus). The generic name must be capitalized when naming a species! It must also describe the group of plants it's naming. For example, the palm genus Trachycarpus means "Rough Fruit".

The second word we use is the specific epithet. The specific epithet must be lower case! It does not have to describe the plant. For example, the specific epithet for the species Trachycarpus fortunei was named after Robert Fortune, the botanist who brought it from Asia to Europe.

To name a species we simply put the genus and specific name together with the genus capitalized and specific epithet in lower case. Both words must be emphasized (italic, underline) in the following format:

Genus specific epithet -> Trachycarpus fortunei

You may also see more names after species name. One of the ranks lower than the specific epithet is the variety. A variety is used describe a traits which are different among a population. The plant populations of a variety are usually separated geographically but if they are brought together, they will hybridize. The variety usually describes the location or trait in which the variety located or describes. The variety is abbreviated in the name as "var." and it is lower case and emphasized.

3. Another rank that is commonly confused with variety is a cultivar. A cultivar is plant that that is either found in cultivation (not in the wild) or bred my humans to have a specific trait. A cultivar is represented by single quotations around the cultivar name after the specific epithet. Cultivar is abbreviated as cv. and the description name is not emphasized.

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Taxonomy and Ebbryology 11

Example: Musa acuminata cv. 'Gros Michel' 4. -> older cultivar of the common edible banana which used to be found in grocery stores 5. As many of you know, common names may be the same for many different plant species. For example, many of the species in the Opuntia genus (contains several species) share Prickly Pear Cactus as their common name. So how do we name all of the plants and what is a genus?

We use the binomial naming system (scientific name), as the name implies, uses two words to name a particular species.

6. To name a species we simply put the genus and specific name together with the genus capitalized and specific epithet in lower case. Both words must be emphasized (italic, underline) in the following format:

Genus specific epithet -> Trachycarpus fortunei

You may also see more names after species name.

One of the ranks lower than the specific epithet is the variety. A variety is used describe a traits which are different among a population. The plant populations of a variety are usually separated geographically but if they are brought together, they will hybridize. The variety usually describes the location or trait in which the variety located or describes. The variety is abbreviated in the name as "var." and it is lower case and emphasized.

Examples: Opuntia galapageia var. profuse -> This variety cactus blooms much heavier than other plants in its species

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7. Sabal minor var. louisiana -> This variety is located in the state of Louisiana, United States

Another rank that is commonly confused with variety is a cultivar. A cultivar is plant that that is either found in cultivation (not in the wild) or bred my humans to have a specific trait. A cultivar is represented by single quotations around the cultivar name after the specific epithet. Cultivar is abbreviated as cv. and the description name is not emphasized. Example: Musa acuminata cv. 'Gros Michel'

-> older cultivar of the common edible banana which used to be found in grocery stores.

Advantages

The advantages of scientific over common names are that they are accepted by speakers of all languages, that each name applies only to one species, and that each species has only one name.

This avoids the confusion that often arises from the use of a common name to designate different things in different places (), or from the existence of several common names for a single species. There are two international organizatielkons for the determination of the rules of nomenclature and the recording of specific names, one for zoology and one for botany. According to the rules they have established, the first name to be published (from the work of Linnaeus on) is the correct name of any organism unless it is reclassified in such a way as to affect that name (for example, if it is moved from one genus to another). In such a case definite rules of priority also apply.

Q.3 Define botanical garden ?Name the botanical gardens? Ans. A botanical garden (or botanic garden) is a well-tended area displaying a wide range of plants labelled with their botanical names. It may contain specialist plant collections such as cacti and succulent plants, herb gardens, plants from particular parts of the world, and so on; there may be greenhouses, shadehouses, again with special collections such as tropical plants, alpine plants or other exotic plants. Visitor services at a botanical garden might include tours, educational displays, art exhibitions, book rooms, open-air theatrical and musical performances and other entertainment.

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Taxonomy and Ebbryology 13

Botanical gardens are often run by universities or other scientific research organizations and often have associated herbaria and research programmes in plant taxonomy or some other aspect of botanical science. In principle their role is to maintain documented collections of living plants for the purposes of scientific research, conservation, display and education, although this will depend on the resources available and the special interests pursued at each .particular garden.

The origin of modern botanical gardens can be traced to European medieval medicinal gardens known as physic gardens, the first of these being founded during the Italian Renaissance in the 16th century.

Role and functions of botanical garden

availability of plants for scientific research display of plant diversity in form and use display of plants of particular regions (including local) plants sometimes grown within their particular families plants grown for their seed or rarity major timber (American English: lumber) trees plants of economic significance glasshouse plants of different climates all plants accurately labelled records kept of plants and their performance catalogues of holdings published periodically

research facilities utilising the living collections studies in plant taxonomy examples of different vegetation types student education a herbarium selection and introduction of ornamental and other plants to commerce studies of plant chemistry (phytochemistry) report on the effects of plants on livestock at least one collector maintained doing field work

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Botanical Gardens of Delhi

Botanical Garden- Ooty - Ooty

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Taxonomy and Ebbryology 15

Royal Botanic Gardens, Kew

List of botanical gardens in India

Government Botanical Gardens, Ootacamund, Nilgiris district, Tamil Nadu Jawaharlal Nehru Tropical Botanic Garden and Research Institute (TBGRI), Trivandrum, Kerala (Biggest in India and conserves the largest no:of plant species in Asia). Vellayani Agricultural College , Trivandrum, Kerala Agri Horticultural Society of India, Alipore, Kolkata Acharya Jagadish Chandra Bose Indian Botanic Garden, Shibpur, Kolkata Lalbagh, Bangalore, Karnataka IFGTB Botanical Garden - The Institute of Forest Genetics and Tree Breeding (IFGTB), Coimbatore, Tamil Nadu TNAU Botanical Garden, Agriculture University, Coimbatore, Tamil Nadu Jammu and Kashmir Medicinal Plants Introduction Centre, Sonamarag, Kashmir Jhansi Botanical Garden, Jhansi, Uttar Pradesh Saharanpur Botanical Garden, Saharanpur, Uttar Pradesh Semmozhi Poonga, Chennai, Tamil Nadu

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Lloyd's Botanical Garden, Darjeeling, West Bengal Garden of Medicinal Plants, North Bengal University, West Bengal Botanical Garden, Near Sarangpur, Chandigarh Empress Garden, Pune

Q. What is Herbarium and what are their uses? Ans Herbarium: It is a store house where dried and pressed specimens of plants are placed on sheet in a systematic way of classification. They are basically used for education and research purposes in different institutes. Polythene bags, magazines, blotting papers, sheets, field notebook, glue, labels constitute the equipment of herbarium. In order to collect the specimen, first area is selected and then plant with intact parts is collected. This material is placed in polythene bags. The collected specimens are spread over magazine sheets. Magazines are now put inside the press which consists of boards and straps. Details should be noted down in the field notebook. A specific number is given to specimen who provides all relevant details. After a day sheets are changed and blotting papers are required. They provide drying effect. Sheets are color specific and labels are placed over them. Sheets are covered with tissue papers. Formalin solutions are used to preserve the specimen.

Uses of Herbarium

Herbarium is used as an information guide for the local as well as distant area flora. They also help us to identify unknown and wild varieties of plants. They also provide first hand information on morphological variations, seasonal flowering and quick referral system for taxonomic studies. The most important herbaria in India are Central National Herbarium, Kolkata consisting of nearly 2 million herbarium specimens. Madras Herbarium in Coimbatore & National Botanical Research Institute in Lucknow are other well known herbaria. Species are identified by Manuals (handy book with certain guidelines relating to species in particular area), Flora (Informative book with respect to climate, habitat of plants in a specified area), Monograph (thesis with information on particular topic), Catalogue (list with specific numbers of species) and key. Botanical gardens are large sized areas with almost every variety of plants. Hanging Gardens of Babylon are quite popular.

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Taxonomy and Ebbryology 17

Some of the world famous Botanical gardens are in India like Indian Botanical Garden in Kolkata (largest botanical garden in Asia), Lloyd Botanical garden in Darjeeling and National Botanical Garden in Lucknow

Q.4 Define concept of genus and species in plants? Ans A species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or ecological niche. Presence of specific locally adapted traits may further subdivide species into "infraspecific taxa" such as subspecies (and in botany other taxa are used, such as varieties, subvarieties, and formae).

Species that are believed to have the same ancestors are grouped together, and this group is called a genus. A species will be placed in only one genus (although taxonomic opinion might change). Similarity is best checked by the similarity of their DNA,[dubious – discuss] but for practical reasons, other properties are used.

All species are given a two-part name, a "binomial name". The first part of a binomial name is the generic name, the genus of the species. The second part is either called the specific name (a term used only in zoology) or the specific epithet (the term used in botany, which can also be used in zoology). For example, Boa constrictor is one of four species of the Boa genus. The first part of the name is capitalized, and the second part has a lower case. The binomial name is written in italics .A usable definition of the word "species" and reliable methods of identifying particular species are essential for stating and testing biological theories and for measuring biodiversity, though other taxonomic levels such as families may be considered in broad-scale studies. Extinct species known only from fossils are generally difficult to assign precise taxonomic rankings, which is why higher taxonomic levels such as families are often used for fossil-based studies

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Multiple Choice Question

1. Engler and prantl‘s system of classification is a phyloene tic system based on the assumption that the flowering plants where perianth is absent are phylogenetically primitive. 2. Carolus Linnaeus is known as ‗father of modern botany. 3. The gynoecium is monocarpellary and placentation is marginal in members of family papilionaceal. 4. Which of the following is the standard and most famous work of Bentham and Hooker ? A) Species Plantarum B) Genera Plantarum

C) Genera Plantus D) Systema Nature

5. When one specimen or other element is designated by the author as the nomenclatural type it is known as.

A) Holotype B) Prototype

C) Neotype D) Syntyhpe

6. The word ‗taxonomy‘ was first used by :

A) A.P. decandolle B) Carl Linnaeus

C) John Ray D) J.D. Hooker

7. Systematic Botany deals with the

A) Identification of plants B) Inter-relationship

C) Nomenclature of Plants D) All of the above

8. species Plantarum was written by :

A) Carolus Linnaeus B) A.P. Decandolle

C) G. Bentham and J.D. Hooker D) A. Engler and Karl A.E. Prantl

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Taxonomy and Ebbryology 19

9. The standard size of a herbarium sheet is :

A) 28.75 x 41.25 cm B) 25.15 x 40.25 cm.

C) 18.75 x 41.25 cm. D) 28.75 x 35.25 cm.

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Section-B Families

Q.1 Write silent features of angiospermic plants?

Ans. Features:

The sporophyte, which is the dominant plant in the life cycle, is differentiated intoroots stem and leaves. The highest degree of perfection of the vas cular system wit true vessels in the xylem and companion cells in the phloem. The organization of the microsporophylls [stamens] and megasporosphylls [carpels] into a structure called the flower, which is typical only of the angiosperms. The presence of four microsporangia [pollen sacs] per microsporophyll [stamen]. The ovules are always enclosed in an ovary, which is the basal region of the megasporophyll. Production of two kinds of spores, microspores [pollen grains] and megaspores.Angiosperms thus are heterosporous. Presence if a single functional megaspore which is permanently retained within the nucellus or megasporangium. Adaptation f flowers to insect pollination. Pollination consists of the transference of pollen grains from anther to stigma. Spore dimorphism having resulted in the production of gametophytes, male andfemale. Extreme reduction in size, duration of existence and complexity of the gametophytes, which are extremely parasitic. The male gametophyte has reached the limits of reduction. It consists only of the pollen grain and the pollen tube contains the tube nucleus and two male gametes or nuclei. The male cells (gametes) are non-ciliated. The female gametophyte lacks any extensive development of vegetative tissues. Itconsists of three egg apparatus calls, three antipodal cells and twopolarnuclei in thecentre of the embriosac The non-motile male cells or nuclei are carried bodily to the neighborhood of eggapparatus by the pollen tube.

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Taxonomy and Ebbryology 21

Q.2 Describe life cycle of angiosperm ?

Ans. The word "angiosperm" comes from the Greek words for "vessel" and "seed" and translates roughly as "enclosed seed". In part, angiosperms (the flowering plants, phylumAnthophyta) are defined by the fact that their seeds are enclosed by an ovule. The life cycle of an angiospermis defined by the formation of the seed and its development to a full-grown plant which, in turn, produces seeds.

Angiosperms are vascular plants with flowers that produce seeds enclosed in an ovule—a fact that is recognized as the angiospermy condition.

In general, angiosperms have a floral axis with four floral parts, two of which are fertile. At the receptacle, or tip, of the axis there is an ovule-bearing leaf structure known as the carpel. The ovule or ovules can be found inside the pistil. Three portions compose the pistil: the ovary, the style, and the stigma, where the pollen usually germinates

Flower: Reproductive parts

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. Angiosperm Life Cycle

Reproductive Flower Parts

The mature ovule consists of the placenta, the integuments that are modified leaves that cover the entrance to the embryo sac, the micropyle, and the chalaza. These latter two parts of the ovule complement each other in their positions and functions.

While the micropyle receives and guides the pollen tube, the chalaza relates to the vascular supply of the ovule, nutrition, and support. The stamens, which are often composed of the filament and sporangia sacs that make up the anther,

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Taxonomy and Ebbryology 23

surround the pistil. Stamens carry the male gametes, and the pistil carries the female gamete needed for sexual reproduction.

It is believed that the great diversity and adaptability of the angiosperms is related to the presence of a unique reproductive cycle. This cycle consists of an alternation of generations and the production of a pair of spores on two types of sporophylls: microspores (which become male gametophytes) and megaspores (which become female gametophytes).

Development of flowering plants

Different stages of Angiospermic plants (Diploid and Haploid )

Male GameteDevelopment

The angiosperm reproductive cycle begins with the process of microsporogenesis, or microspore formation. The stamen consists of a filament and the anther, also known as the microsporangium. Inmost of the cases, the anther consists of four pollen sacs, or locules.

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Within each locule, the archesporial cell develops through mitosis and extends as a row of cells throughout the entire length of the young anther. These mitotic cell divisions generate the anther wall, which is made up of several cell layers, the outermost of which transforms itself into the epidermis. The layer of cells belowthe epidermis is known as the endothecium.

During anther development, the endothecial cells acquire thickenings whose function is related to anther opening and pollen release. The innermost layer of the anther wall is the tapetum,whose primary function correlates with the nourishment of the young pollen and the deposition of the exine, a coating of the pollen grain.

As development proceeds, the sporogenous cells located below the tapetum transform into microsporocytes. These microsporocytes will undergo meiosis, and tetrads (units of four) of microspores will form.

Shortly after their formation, the tetrads separate into individual microspores. Each microspore is haploid, and often it will enlarge and separate from the tetrad, becoming sculptured by the deposition of sporopollenin and other substances that will turn into the ornamented surface of the pollen grain.

The second phase of pollen development is known asmicrogametogenesis. Themicrospore is the first cell of the gametophytic generation, the cell that generates themature pollen. The single-nucleus microspore develops into the male gametophyte before the pollen is released.

This developmental process occurs through two or three unequalmitotic divisions of the nucleus and subsequent cytokinesis (cell separation). The two daughter nuclei and cells differ in size and in form.

The larger cell represents the tube cell and nucleus,while the smaller cell represents the generative cell and nucleus. At maturity, the grain can be shred in two or three nucleate conditions. When the anther opens, the mature male gametophytes or pollen grains will be disseminated and ready for germination.

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Taxonomy and Ebbryology 25

Multiple Choice Question

1. Gynobasic style is found in family Lamiaceae. 2. Verticillaster is the characteristic inflorescence of the members of family Lamiaceae. 3. The inflorescence is a cyanthium in Euphorbia. 4. In members of poaceae, the basic unit of the inflorescence is spikelet. 5. In Triticum, the pericmth is highly modified structure, represented by two minute structures known as lodicules. 6. All the cereals belong to the family Poaceae. 7. Name the weed belonging to the family Asteracesae which is a fourning problem in almost all the states of India. A.) Parthenium Hysterophorus B.) Ageratum Conyzoides C.) Tagetes Patula D.) Xanthium stramonium 8. Vexillary aestivation is seen in the members of family A.) Rosaceal B.) Cucurbitaceae C.) Fabaceae D.) Poaceae 9. Androgynophore is seen in the members of family : A.) Capporidaceae B.) Mimosaceae C.) Papilionaceae D.) All of the above 10. The fruit is a cremocarp in the members of family : A. Apiaceae B.) Rubiaceae C. Asteraceae D.) Poaceae 11. An umbel inflorescence is the characteristic of the family : A.) Apiaceae B.) Clusiaceae C.) Asteraceae D.) Fabaceae 12. Members of Apocynaceas differ from asclepiadaceae in having

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A.) Latex B.) Corona C.) Translators D.) Bicarpellary Ovary 13. Production of flowers which never open is known as Cleistogamy. 14. The effect of pollen grains on the tissues of seed coat is called metaxenia

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Taxonomy and Ebbryology 27

Section-C

Embryology & Development

Q.1 Define structure of anther and their development?

Ans. The stamen (plural stamina or stamens, from Latin stamen meaning "thread of the warp") is the pollen-producing reproductive organ of a flower. Stamens typically consist of a stalk called the filament (from Latin filum, meaning "thread"), and an anther (from Ancient Greek anthera, feminine of antheros "flowery," from anthos "flower"), which contains microsporangia. Anthers are most commonly two-lobed and are attached to the filament either at the base or in the middle portion. The sterile tissue between the lobes is called the connective.

A typical anther contains four microsporangia. The microsporangia form sacs or pockets (locules) in the anther. The two separate locules on each side of an anther may fuse into a single locule. Each microsporangium is lined with a nutritive tissue layer called the tapetum and initially contains diploid pollen mother cells. These undergo meiosis to form haploid spores. The spores may remain attached to each other in a tetrad or separate after meiosis. Each microspore then divides mitotically to form an immature microgametophyte called a pollen grain.

The pollen is eventually released by the opening (dehiscence) of the anther, generally by means of longitudinal slits, but sometimes by pores, as in the heath family (Ericaceae), or by valves, as in the barberry family (Berberidaceae). In some plants, notably members of the Orchidaceae and the Asclepiadoideae, the pollen remains in masses called pollinia, usually specialised in ways adapted to being carried by particular pollinating agents such as birds or large insects. More commonly, mature pollen grains separate and are dispensed in ways suitable for wind or water transport, or for dusting onto pollinating insects, whether large or small.

When ready, the pollen is carried by some external agent (wind, water or some member of the animal kingdom) to the receptive surface of the carpel of the same or another flower. This process is known as pollination. After successful pollination, the pollen grain (immature microgametophyte) completes its development by growing a pollen tube and undergoing mitosis to produce two male gametes (sperm).

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Stamens in context

The stamens in a flower are collectively called the androecium (from Greek andros oikia: man's house). The androecium forms a whorl surrounding the gynoecium (carpels) and inside the perianth (the petals and sepals together) if there is one. (The one exception is a few members of the family Triuridaceae, particularly Lacandonia schismatica, in which the gynoecium surrounds the androecium.)

Stamens can be free or fused in various ways. A column formed from the fusion of multiple filaments is known as an androphore.

Developmental Stages of Anther

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Taxonomy and Ebbryology 29

T.S. of Anther

Q.2 Diagrame of anther type on the basis of their dehiscence ?

Ans.

Anther Type

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Examples of Anther types

Tapetum type

Microsporogenesis

Q.3 Describe the structure of ovule ?

Ans. Structure of the ovule

Ovule means "small egg". In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integument(s) forming its outer layer(s), the nucellus (or megasporangium), and the megaspore-derived female gametophyte (or megagametophyte) in its center. The megagametophyte (also called embryo sac in flowering plants) produces an egg cell (or several egg cells in some groups) for fertilization. After fertilization, the ovule develops into a seed.

Each ovule is provided with two coats, an outer and an inner. These coats are known as the integuments. In some ovules, however, there is only one

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Taxonomy and Ebbryology 31

integument. Enclosed within these integument, and forming the bulk of the ovule, there is a special kind of tissue called the nucellus. The nucellus is very rich in reserve food materials. Lying embedded in the nucellus, is the most important part of the ovule. This is a sac-like structure (or cell) known as the embryo sac. The ovule is attached to the placenta by a small stalk called the funicle. The two integuments do not cover the nucellus completely, but leave a minute opening at the top. This is the micropyle and it leads to the nucellus. The integuments and the nucellus are free from each other at all places except at the base where they are completely fused. This place of fusion is known as the chalaza. The place where the funicle enters the ovule is called the hilum

Structure of ovule Ovule parts and development

The ovule appears to be a modified megasporangium with integuments surrounding it. Ovules are initially composed of diploid maternal tissue, which includes a megasporocyte (a cell that will undergo meiosis to produce megaspores). Megaspores remain inside the ovule and divide by mitosis to produce the haploid female gametophyte or megagametophyte, which also remains inside the ovule. The remnants of the megasporangium tissue (the nucellus) typically remain inside the ovule. Megagametophytes produce archegonia (lost in some groups such as flowering plants), which produce egg

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cells. After fertilization, the ovule contains a diploid zygote and then embryo of the next sporophyte generation. In flowering plants, a second sperm nucleus fuses with other nuclei in the megagametophyte forming a typically polyploid (often triploid) endosperm tissue, which serves as nourishment for the young sporophyte.

Integuments, chivai and chalaza

The origin of the second or outer integument has been an area of active contention for some time. The cupules of some extinct taxa have been suggested as the origin of the outer integument. A few angiosperms produce vascular tissue in the outer integument, the orientation of which suggests that the outer surface is morphologically abaxial. This suggests that Caytoniales or Glossopteridales cupules may have An integument is a protective cell layer surrounding the ovule. Gymnosperms typically have one integument (unitegmic) while angiosperms typically have two (bitegmic). The evolutionary origin of the integuments, especially the second integument typical of angiosperms remains obscure. The inner integument (which is integral to the formation of ovules from megasporangia) has been proposed to have formed from sterile branches surrounding a terminal megasporangium.[1] Elkinsia, a preovulate taxon, has a lobed structure fused to the lower third of the megasporangium, with the lobes extending upwards in a ring around the megasporangium. This might, through fusion between lobes and between the structure and the megasporangium, have produced an integument.

produced the outer integument of angiosperms.

The integuments develop into the seed coat when the ovule matures after fertilization.

The integuments do not enclose the nucellus completely but leave an opening at its apex referred to as the micropyle. The micropyle opening allows pollen to enter the ovule for fertilization. In gymnosperms (e.g., conifers), the pollen itself is drawn into the ovule and the micropyle opening closes after pollination. In angiosperms, only a pollen tube enters the micropyle. During germination, the seedling's radicle emerges through the micropyle.

Located opposite from the micropyle is the chalaza where the nucellus is joined to the integuments. Nutrients from the plant travel through the phloem of the vascular system to the funiculus and outer integument and from there apoplastically and symplastically through the chalaza to the nucellus inside the ovule. In chalazogamous plants, the pollen tubes enter the ovule through the chalaza instead of the micropyle opening.

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Taxonomy and Ebbryology 33

Nucellus, megaspore and perisperm

The nucellus (plural: nucelli) is the central portion of the ovule inside the integuments. It functions as a megasporangium. In immature ovules, the nucellus contains a megasporocyte (megaspore mother cell), which undergoes sporogenesis via meiosis. Three of the four haploid spores produced in meiosis typically degenerate, leaving one surviving megaspore inside the nucellus, but in some cases more survive. After fertilization, the nucellus may develop into the perisperm that feeds the embryo. In some plants, the diploid tissue of the nucellus can give rise to a seed through a mechanism of asexual reproduction called nucellar embryony.

The ovule (female sex organ) consists of two opposite ends: the micropyle, where the integuments come together, and a more distant end, where the ovular tissue is more massive. This part is also known as the chalaza, and it lies directly opposed to the micropyle.

The mature ovule is composed of three layers: the outer integument; the inner integument; and, underneath the integuments, the nucellus. During ovular development, one cell lying below the nucellar epidermis changes into a primary archesporial; this will divide to form the primary parietal cell and primary sporogenous cell.

Q.4. Explain types of ovules?

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Ans. Depending when the relative position of micropyle at maturity following some type of ovules has been recognized.

1- orthotrophoes ovules – when the body is upright with micro poly chalaza and funide falling in straight line. 2- Anatropous ovules- due to unilatral growth of funicle whole body of the ovules is in verted through 180' as a micro poly comes close to base of the funicle. 3- Campylotropous ovules- this ovules has curved body its ceurateue is less than of anatropus ovule. 4- Amphitropaus – the ovules have a pronocencid curved body, but embryo sac with in the ovules and become horse shoe. 5- Hemi –anatropous

On the basis of integument-

Ovule are of two types-unitegmic and bitegmic

On the basis of position of micropyle-

Ovule are of following types

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Taxonomy and Ebbryology 35

Q. 5 Explain development of female gametophyte?

ANS Development stages of female gametophyte

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DIGAGRAME:STAGES OF DEVELOPMENT

The primary sporogenous cell functions as the megaspore mother cell, which divides meiotically, originating four haploid megaspores. In the majority of angiosperms, three of the megaspores will degenerate, and only the chalazal one will develop into the megagametophyte (embryo sac).

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Taxonomy and Ebbryology 37

After the completion of the embryo sac stage, a series of cellular events occurs, ending with the formation of the mature embryo sac, ready for fertilization by the male gametes. The chalazal megaspore enlarges and undergoes three mitoses, giving rise to eight haploid cells. The mature megagametophyte consists of two groups of four cells locaed at both ends of the embryo sac

The result is three antipodals at the chalazal end: the egg apparatus (consisting of the egg and two synergids at the micropylar end) and the polar nuclei. These two cells, present at both ends, usually fuse before pollination, and during fertilization they form the primary endosperm nucleus.

Q. 6 Define pollination and fertilization ?

Ans Pollination is the process by which pollen is transferred in the reproduction of plants, thereby enabling fertilization and sexual reproduction. .thepollen must be transferred from the anther to the stigma. Biotic agents (such as birds, insects, or

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mammals) or abiotic agents (such as wind or water) can accomplish this transfer process, known as pollination.

pollination is a phase in the alternation of generations: each pollen grain is a male haploid plant, a gametophyte, adapted to being transported to the female gametophyte, where it can achieve fertilization by producing the male gamete (or gametes, in the process of double fertilization).

As such the Angiosperm successful pollen grain (gametophyte) containing the male gametes (sperm) gets transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary. Its two gametes travel down the tube to where the gametophyte(s) containing the female gametes are held within the carpel.

One nucleus fuses with the polar bodies to produce the endosperm tissues, and the other with the ovum to produce the embryo[1][2] Hence the term: "double fertilization".

The receptive part of the carpel is called a stigma in the flowers of angiosperms. Pollination is a necessary step in the reproduction of flowering plants, resulting in the production of offspring that are genetically diverse.

After landing on the stigma, pollen tubes will emerge through the grain apertures if the environ- ment is high in humidity. Successful germination of the pollen in

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Taxonomy and Ebbryology 39

the stigma requires nutrients. In most plants, growth of the pollen tube lasts between twelve and forty-eight hours, frompollen germination to fertilization.

Pollen germination starts with pollen-tube initiation, elongation, and penetration of the stigmatic tissue. During this period intense metabolic activity takes place, for the tube must synthesize membrane material and cell wall for growth and expansion. Simultaneously, at its tip the tube carries the vegetative cell nucleus, fol- lowed by the germinative cell.

Type of pollination :‖

self-pollination and cross-pollination. In self-breeding species, the pollen comes from the anther of the same flower In cross-pollination (or out crossing) species, the pollen comes from the anthers of a different flower or even a different plant of the same species. In these plants, incompatibility in the stigma guarantees that only pollen from other flowers will germinate.

Q7 What is fertilization? Explain double fertilization?

Ans When a pollen grain reaches the stigma, it germinates into a pollen tube.The germ cell divides by mitosis forming 2 sperm cells. These, along with the tube nucleus, migrate down the pollen tube as it grows through the style, the micropyle, and into the ovule chamber and fuse with egg cell this prosses is called fertilization. The union of one sperm with the egg is known as fertilization The pollen tube with its contents makes up the mature male gametophyte generation.

Once the sperm reach the micropyle , the growth of other tubes stops. In the embryo sac (female gametophyte), four cells are located at themicropylar side.Of those four, the first pair that the spermcells will encounter are the synergids.

One of these is always bigger than the other and carries the filiform apparatus, a structure resembling hairs that degenerates after pollination and before fertilization. The synergids act as chemical attractants to the pollen tube, which penetrates the synergids via the filiform apparatus and then releases the two sperm cells.

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sperm cell will fuse with the primary endosperm nucleus, generating the endosperm. The remaining cells of the female gametophyte are the antipodals; they usually degenerate after fertilization has taken place.

Double fertilization The pollen tube enters the ovule through the micropyle and ruptures.

One sperm cell fuses with the egg forming the diploid zygote. The other sperm cell fuses with the polar nuclei forming the endosperm nucleus. Most angiosperms have two polar nuclei so the endosperm is triploid (3n). The tube nucleus disintegrates

Q.8 Structure and development of microspore or microsporogenesis ? Ans Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes (sperm cells). Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the female cone of coniferous plants. When pollen lands on a compatible pistil or female cone (i.e., when pollination has occurred), it germinates and produces a pollen tube that transfers the sperm to the ovule (or female gametophyte). Individual pollen grains are small enough to require magnification to see detail.

The structure and formation of pollen Pollen itself is not the male gamete.[1] Each pollen grain contains vegetative (non- reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell containing two nuclei: a tube nucleus (that produces the pollen tube) and a generative nucleus (that divides to form the two sperm cells). The group of cells is surrounded by a cellulose-rich cell wall called the intine, and a resistant outer wall composed largely of sporopollenin called the exine.

Pollen is produced in the 'microsporangium' (contained in the anther of an angiosperm flower, male cone of a coniferous plant, or male cone of other seed

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Taxonomy and Ebbryology 41

plants). Pollen grains come in a wide variety of shapes (most often spherical), sizes, and surface markings characteristic of the species (see electron micrograph, right). Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the forget-me-not (Myosotis spp.), is around 6 µm (0.006 mm) in diameter. Wind-borne pollen grains can be as large as about 90-100 µm.[2] The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archeology, and forensics.

In angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, four groups of sporogenous cells form within the anther.

The fertile sporogenous cells are surrounded by layers of sterile cells that grow into the wall of the pollen sac. Some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells. In a process called microsporogenesis, four haploid microspores are produced from each diploid sporogenous cell (microsporocyte), after meiotic division. After the formation of the four microspores, which are contained by callose walls, the development of the pollen grain walls begins. The callose wall is broken down by an enzyme called callase and the freed pollen grains grow in size and develop their characteristic shape and form a resistant outer wall called the exine and an inner wall called the intine. The exine is what is preserved in the fossil record.

The pollen wall protects the sperm nucleus while the pollen grain is moving from the anther to the stigma; it protects the vital genetic material from drying out and solar radiation. The pollen grain surface is covered with waxes and proteins, which are held in place by structures called sculpture elements on the surface of the grain. The outer pollen wall, which prevents the pollen grain from shrinking and crushing the genetic material during desiccation, is composed of two layers. These two layers are the tectum and the foot layer, which is just above the intine. The tectum and foot layer are separated by a region called the columella, which is composed of strengthening rods. The outer wall is constructed with a resistant biopolymer called sporopollenin. The pollen tube passes through the wall by way of structures called apertures.

Pollen apertures are any modification of the wall of the pollen grain. These modifications include thinning, ridges and pores, they serve as an exit for the pollen contents and allow shrinking and swelling of the grain caused by changes in moisture content. The elongated apertues/ furrows in the pollen grain are

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called colpi (singular: colpus) which along with pores, are a major criterion for the identification of classes of pollen .[4] Pollen grains may have furrows, the orientation of which (relative to the original tetrad of microspores) classify the pollen as colpate or sulcate. The number of furrows or pores helps classify the flowering plants, with eudicots having three colpi (tricolpate), and other groups having one sulcus.

Except in the case of some submerged aquatic plants, the mature pollen-grain has a double wall, a thin delicate wall of unaltered cellulose (the endospore or intine) and a tough outer cuticularized exospore or exine. The exine often bears spines or warts, or is variously sculptured, and the character of the markings is often of value for identifying genus, species, or even cultivar or individual. In some flowering plants, germination of the pollen grain often begins before it leaves the microsporangium, with the generative cell forming the two sperm cells

Microscopic view of cross section of an anther showing pollen sacs

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Taxonomy and Ebbryology 43

Developing pollen: Microspore mother cells in pollen sacs divideby meiosis to produce the four cells seen here in each cluster. They are known as tetrads.

Cells in each tetrad grow and separate while in pollen sacs to form mature pollen grains seen here. Nuclei divide by mitosis to produce the male gametophytes seen here inside each pollen grain.

Male gametophyte development in higher plants is a complex process that requires the coordinated participation of various cell and tissue types and their

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associated specific gene expression patterns. The male gametophytic life cycle can be divided into a developmental phase leading to the formation of mature pollen grains, and a functional or progamic phase, beginning with the impact of the grains on the stigm a surface and ending at double fertilisation. Pollen ontogeny is also an excellent model in which to dissect the cellular networks that control cell growth, polarity, cellular differentiation and cell signaling. Here we present an overview of important cellular processes in male gametophyte development and recent advances in genetics and genomic approaches that are advancing the field significantly.

Genetic approaches have identified a growing number of gametophytic mutants affecting discrete steps during the developmental or progamic phases that are now beginning to uncover some of the key molecular processes involved. With recent technological advances pollen transcriptomic studies now provide the first genome-wide view of male reproductive cell development in Arabidopsis These studies reveal at least two successive global gene expression programs and the identity of a large number of male gametophyte-specific genes and putative transcriptional regulators. Transcriptome analysis has revealed a striking overrepresentation of cell wall metabolism, cytoskeleton and signaling genes in preparation for the progamic phase. This quantum leap in gene-centered knowledge highlights the functional specialization of this pathway and offers many new opportunities for the dissection of cell.

INTRODUCTION – MALE GAMETOPHYTE

Male gametophyte development in higher plants is a complex process that requires the coordinated participation of various cell and tissue types and their associated specific gene expression patterns. Both gametophytic (pollen) and sporophytic (anther, tapetum) tissues participate in this process. The male gametophytic life cycle can be divided into two distinct phases: (1) a developmental phase, which takes places within the anther locules, and leads to formation of mature pollen grains, and (2), the functional or progamic phase, which begins with the impact of the grains on the stigma surface, continues with pollen tube growth and ends at double fertilisation. Developmentally, it is a simple and highly reduced system compared with the sporophyte and therefore provides unique opportunities to study the developmental regulation of gene expression and functional interactions between different cell types. With regard to microsporogenesis, a large body of evidence shows that gametophytic gene expression is both complex and extensive. Moreover, a large fraction of such genes is also expressed in the sporophyte. This phenomenon of ―haplo-diploid transcription‖ has important implications with respect of the efficiency of gametophytic selection and its role in the evolutionary

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Taxonomy and Ebbryology 45

success of flowering plants. Competition between male gametophytes for fertilization of a limited number of egg cells is common, and pronounced differences in pollen tube growth rate reflect genetic differences between individual microgametophytes (Mulcahy 1979, Mulcahy et al. 1996). Gametophytic selection provides a barrier against poorly functioning haploid genomes, serving to reduce the influence of random events and to promote the rigorous selection of superior haploid genotypes. These conditions argue for the rapid evolution of gametophytic genes that encode specialized functions that improve the fitness of the male gametophyte. On the contrary, gametophytic selection can influence sporophytic fitness only if there is significant overlap between genes expressed in both generations (Mulcahy 1979, Mulcahy et al. 1996). Recent transcriptomic studies of developing male gametophytes conclusively demonstrate that the extent of haplo-diploid overlap is greater than 95% (Honys and Twell 2004, Twell et al. 2006) thereby providing enormous potential for the gametophytic selection of genes affecting sporophytic traits. Honysetal. Male gametophyte develoular processes that contr.

POLLEN DEVELOPMENT

Pollen development begins in the young anther locules and consists of two major phases -microsporogenesis and microgametogenesis. The primary sporogenous layer gives rise to the diploid microsporocytes or meiocytes. Meiotic division produces tetrads of four haploid microspores enclosed within a unique callosic (β -1, 3-glucan) cell wall. Callose is degraded by the activity of an enzyme complex (callase) secreted by the tapetum leading to the separation of tetrads into individual microspores (Fig. 1). This demonstrates tight co-operation of sporophytic and gametophytic tissues. Separation of tetrads into individual microspores is under sporophytic control (Preuss et al. 1994) and in quartet3 mutants microspores remain attached in a tetrad as a result of a mutation in a polygalacturonase, normally secreted from the tapetal cell layer (Rhee et al. 2003). Microspore growth and development proceed through a progressive cycle of vacuole biogenesis, fusion and fission events (Owen and Makaroff 1995, Yamamoto et al. 2003).The morphogenetic role of the vacuole in microspore expansion is associated with extreme polarization of the microspore nucleus against the microspore wall. Polarization of the microspore nucleus may provide a signal for entry into the highly asymmetric cell division at pollen mitosis I (PMI). Pollen mitosis I gives rise to two daughter cells with completely different structures and cell fates (Twell et al.1998). The large vegetative cell has dispersed nuclear chromatin and constitutes the bulk of the pollen cytoplasm. In contrast,

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the smaller generative cell has condensed nuclear chromatin and contains relatively few organelles and stored metabolites. Whereas the vegetative cell exits the cell cycle at G1 phase, the generative cell remains division-competent and completes pollen mitosis II (PMII) to form the two sperm cells. Asymmetric cytokinesis following PMI possesses two special features in that: (1) no preprophase band of microtubules marks the future division plane, and (2) a unique curved cell plate is formed to enclose the generative nucleus. Two general models have been proposed to account for differential cell fate arising from asymmetric division at PMI (Eady et al. 1995). Both assume that vegetative cell gene expression is the default pathway resulting from the accumulation of gametophytic factors, and provide alternative mechanisms to explain how vegetative c ell-specific genes are repressed in the generative cell. In essence gametophytic determinants may be simply excluded from the generative cell pole, or polarized hypothetical generative cell repressors may block vegetative cell-specific gene expression. It is possible that a com bination of both mechanisms operate to specify and effectively seal generative cell fate through asymmetric cell division.

After pollen mitosis I, the generative cell migrates inward resulting in a ‗cell within a cell‘ structure, enabling gamete transport within the pollen tube. Generative cell migration follows degradation of the callose wall that separates the vegetative and generative cells. This presumably involves targeted secretion of β (1-3)-glucanases. Subsequently, the generative cell forms an elongated or spindle-like shape that is maintained by a cortical cage of bundled microtubules.

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Taxonomy and Ebbryology 47

The generative cell un dergoes further mitotic division at pollen mitosis II (PMII) to produce the two sperm cells. In tricellular pollen this division occurs within the anther, whereas in bicellular pollen it occurs within the growing pollen tube. Although the majority of flowering plants produce bicellular pollen, many important food crop plants such as rice, wheat and maize produce short-lived, tricellular pollen grains (Figs. 1, 2 ). Pollen mitosis II takes place within a membrane-bound compartment of the vegetative cell cytoplasm and a physical association is established between the gametes and the vegetative nucleus known as the male germ unit (MGU). The MGU exists in both bicellular and tricellular pollen systems and is thought to be important for the coordinated delivery of the gametes and sperm cell fusion events (Dumas et al. 1998). In Arabidopsis the MGU is first assembled in tricellular pollen (Lalanne and Twell 2002). During pollen maturation the vegetative cell accumulates carbohydrate and/or lipid reserves required for the demands of plasma membrane and pollen tube wall synthesis (Pac ini 1996). The substantial accumulation of RNA and proteins during the final phases of pollen maturation (re viewed in Twell 2002) is functionally required for rapid pollen tube growth after pollination. Pollen grains are usually strongly dehydrated when finally released from the anthers. During this maturation phase, the accumulation of sugars and proline or glycine-betaine are thought to act as osmoprotectants to protect vital membranes and proteins (Schwacke et al. 1999).

Cell wall

The specialized activities and biological role of the pollen grain are reflected in the unique composition of the pollen wall. The pollen wall and its coatings isolate and protect the male gametophyte and its precious cargo, and mediate the complex communication with the stigma surface (Scott et al. 2004).

The pollen wall consists of inner intine and outer exine layers. Its synthesis begins in the microspores newly formed within the tetrad, when the pectocellulosic intine and the primexine are laid down. The primexine serves as a matrix for deposition of sporopollenin precursors and their polymerisation. Sporopollenin is one of the most resistant biopolymers known and is a complex containing fatty acids and phenylpropanoids. Although the pathways involved in sporopollenin formation remain unknown its synthesis involves tight cooperation between microspore cytoplasm and tapetal cells. The exine is not evenly distributed over the pollen grain surface and regions with reduced thickness or that lack sporopollenin can form apertures that are used as sites for pollen tube emergence. The number and size of apertures and exine patterning are also under strict

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sporophytic control. The formation of pollen coatings is completed at later stages of microgametogenesis during which remnants of degenerating tapetal cells are deposited onto the pollen grain surface. The pollen coat is involved in pollen- pistil signalling, self incompatibility, pollen hydration, adhesivity, color and odour. The yellow or purple colours of mature pollen grain results from the presence of both carotenoid and phenylpropanoid compounds. These features as well as the elaborate patterning of sporopollenin are highly variable among different plant species. In animal-pollinated species pollen is often decorated with elaborate structures that facilitate vector adhesion, whereas in wind pollinated species pollen lacks such sculpturing (Fig. 3).

Q9 What is Tapetum? give its type?

Ans.

Tapetum is a neutritive large of micro space. It nutralize the space present in side the pollen chamber .It present in 2 forms.

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Taxonomy and Ebbryology 49

seceretory tapetum or glandular tapetum- They remain intact and continuously secreate food nutrition to developing microspore.

Amoeboid tapetum / pereplasmodial tapetum-

They destroyed and provide food .Inner wall are absent in ameboid tapetum cells.

On basis of origion tapetam is of 2 types-

P- Tapetum – tapetam formed by parietal wall.

C- Tapetum – tapetum formed by connictive tissue cell.

Function of tapetum

1- They secreate callose enzyme. it decompose cellulose which is necessary for separation of spores from tetrad.

2- Sereation of libisch bodies – it is made up or by particles of lipid modules which supply food from pollen kit to the pollen grain

3- Pollen kit substance-

Enveloper and pollen grain

Lipid modules- ubisch bodies

Sporo pollenin - protein and lypo protein –tapetum

Tapetum cell DNA consists is maximum cause there cell are

Multi nucliated

Endomitosis- cause of free nuclear division in a cell

Poly tene- in formation of more than 2 tetrad in a chromosomes.

Restituation nuclei – formation of more than one nucleus in a nuclous this is called Pestritution nuclei.

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Q10 Give development maleGametophyte?

Ans. - Formation of generative and vegetative cells.

The First division of pollen grain result in two unequal cell- a larger vegetable cell and a smaller generative cell. Generative cell is attached to intine of the pollen wall but letter become free and lies in cytoplasm of vegetative cell the pollen grain. When from the tatred are ceninucliate. Thus is no synchronization in the first division in the pollen grains of an another locale but the difference in timing in different pollen grain are not the protoplast of pollen shows two marpid changes before its division.

1- It nuclues migrates from the centre to periphery the centre to periphery the mirg ration occuse in definate diriction determine the position of the generative cell.

2- Many vacuoles appear in b/w the nucleus and pollen wall on the side when vegetative cells to be formed.

3- To the daughter nuclei formed in a Pollen the one laying towards the pollen wall is generative nucleus and the other function as the vegetative nucleus. Then covered wall is formed b/w 2 nuclei. Which cuts off the generative nucleus in a small cell. It become free from the pollen wall. This cell gets surrounded by the cytoplasm of the vegetable cell. The shape of tentative cell may become ellpsoidal fusiform. The cytoplam of vegetable cell contain ribosome RER plastedi. RNA and protein are also present in safficient amounts, the wall of genrative cell is irugular these is no conniction b/w vegetable cell. The made gametes are formed by mitric division of The genuatire cell. This division usually occeue before the pollen shed from another. It into pollen tube. pollen are shed at two called condition, this viable for longer period. Then mitotic division of generative cells results in the formation of two non mobile male gamete. Each male gamete consists of a large nucleus by a then sheath of cytoplasm.

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Taxonomy and Ebbryology 51

Multiple Choice Question

1. When a style arises from the base of the ovary it is known as – A) Plumose B) Linear C.) Gynobasic D) Terminal 2. Fertirized egg is called : A) Zygote B) Ovule C) Embryo D) Seed 3. The condition in which anothers & stigma of a flavers present on the same plant is called : A) Autogamy B) Homogamy C) Herkogamy D) Geitonogamy 4. When pollen tube enters the ovule through micropyle, the process is called : A) Porogamy C) Mesogamy C) Chalazogamy D) Aporogamy 5. Development of megaspore within ovule is known as : A) Parthenogenesis C) Megasporogenesis C) Megagametogenesis D) Embryogenesis 6. A microspore is a first cell of A) Male sparophyte B) Female sporophyte C) Male gametophyte D) Female gametophyte 7. The triploid nucleus formed as result of double fertilization or triple fusion, functions as the primary endosperm nucleus. 8. The mature anther wall is made of the four layers, viz. dpidermis, middle layers and tapetum

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Section-D Seed Embryology

Q. 1 Define Structure of Seed and Fruit Formation ?

Ans.

Seeds After double fertilization, each ovule develops into a seed, which consists of

a plumule, made up of o two embryonic leaves, which will become the first true leaves of the seedling, and o a terminal (apical) bud. The terminal bud contains the meristem at which later growth of the stem takes place. One or two cotyledons which store food that will be used by the germinating seedling. o Angiosperms that produce seeds with two cotyledons are called dicots. Examples: beans, squashes, Arabidopsis o Angiosperms whose seeds contain only a single cotyledon are monocots. Examples: corn and other grasses. The hypocotyl and radicle, which will grow into the part of the stem below the first node ("hypocotyl" = below the cotyledons) and primary root respectively.

The development of each of the parts of the plant embryo depends on gradients of the plant hormone, auxin.

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Taxonomy and Ebbryology 53

In addition to the embryo plant (derived from the zygote), each seed is covered with protective seed coats derived from the walls of the ovule

dispersal of the species to new locations (aided in angiosperms by the fruit) survival of the species during unfavorable climatic periods (e.g., winter). "Annual" plants (e.g., beans, cereal grains, many weeds) can survive freezing only as seeds. When the parents die in the fall, the seeds remain alive — though dormant— over the winter. When conditions are once more favorable, germination occurs and a new generation of plants develops.

The food in the cotyledons is derived from the endosperm which, in turn, received it from the parent sporophyte. In many angiosperms (e.g., beans), when the seeds are mature, the endosperm has been totally consumed and its food transferred to the cotyledons. In others (some dicots and all monocots), the endosperm persists in the mature seed.

The seed is thus a dormant embryo sporophyte with stored food and protective coats. Its two functions are

Q2- Explain embryo development in dicot ? Ans.- In most of the dicotyledons the apical cell of the two called proembryo dividis longitudinally or transveusaly and the basal cell may remain undivided or may further devide trans versly in the basics of the cellular configuration of the embryo at the four called stagi and the part played by each of these in the organegic development. these are different type of embryo in dicots but we consider curifor and onagrad type of embryo the first division of zygote is by a

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trans verse wall and as a result an apical cell and a basal cell are differentiated. The basal cell of the two called embryo lies close to micro poly when as the apical cell lies on the innre side the basal cell dividis by a transverse wall and apical the two terminal cells formed by longitudinal division of the apical cell divide by a longitudinal wall at right angle of the first and thus a quadrant is formed each cell of quadrant divided by trans ever wall giving to octant stage.

Embryo Formation

The fertilised egg undergoes a regular sequence of divisions to form the embryo. The oospore divides to form a suspensor or basal cell and a terminal embryo cell.

The basal cell is towards the micropyle and the terminal cell is towards the chalaza. The basal cell divides repeatedly to produce a row of 4 to 8 cells. This constitutes the suspensor. The terminal cell divides in various planes to form a cluster of cells called the proembryo. The suspensor pushes the proembryo in to the endosperm, to enable the developing embryo to obtain nourishment.

(A - H). Stages in the development of dicot embryo in Capsella bursa-pastorisThe pro embryo cell divides to form the plumule, radicle and two cotyledons in the dicots. In monocots only one cotyledon develops.

As the embryo and endosperm mature, the integuments of the ovule becomes hard to form the seed coat, which protects the seed.

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Taxonomy and Ebbryology 55

Growth of an embryo in a non-endospermous dicotyledon seed, such as shepherds purse (Capsella bursapastoris)

Q.3 Describe characters of family euphorbiaceae and its Economic importance?

Ans Euphobiaceae: Euphorb Family

This family consists of a wide array of different plants. There are approximately 300 genera and 7,500 species. Some of these plants are mistaken for cacti because the family has members that have adapted succulent, photosynthetic stems, highly reduced leaves and spines. Very different however from cacti, is the presence of milky sap and the unique structure of the flowers. Many Euphorbs like Jathropa are extremely toxic.

Systematics: Euphorbs are all unisexual flowers. They range from 1) normally developing flowers to reduced flowers (maybe even just naked pistils) to 3) a highly reduced cyatheum. Cyatheums look like normal flowers but instead are many flowers combined into one structure that looks like a normal flower. The family has milky sap. There are peltate hairs. There are 3 carpels, 3 locules and 3 style branch

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Euphorbiaceae, the Spurge family are a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees. Some are succulent and resemble cacti.

This family occurs mainly in the tropics, with the majority of the species in the Indo-Malayan region and tropical America a good second. There is a large variety in tropical Africa, but it is not as abundant or varied as in these two other tropical regions. However, Euphorbia also has many species in non-tropical areas such as the Mediterranean Basin, the Middle East, South Africa, and southern USA.

The leaves are alternate, seldom opposite, with stipules. They are mainly simple, but where compound, are always palmate, never pinnate. Stipules may be reduced to hairs, glands, or spines, or in succulent species are sometimes absent.

The radially symmetrical flowers are unisexual, with the male and the female flowers usually occurring on the same plant. As can be expected from such a large family, there is a wide variety in the structure of the flowers. They can be monoecious or dioecious. The stamens (the male organs) can number from 1 to 10 (or even more). The female flowers are hypogynous, that is, with a superior ovary.

The genera in tribe Euphorbieae, subtribe Euphorbiinae (Euphorbia and close relatives) show a highly specialized form of pseudanthium ("false flower" made up of several true flowers) called a cyathium. This is usually a small cup-like involucre consisting of fused together bracts and peripheral nectary glands, surrounding a ring of male flowers, each a single stamen. In the middle of the cyathium stands a female flower: a single pistil with branched stigmas. This whole arrangement resembles a single flower.

The fruit is usually a schizocarp, sometimes a drupe. A typical schizocarp is the regma, a capsular fruit with three or more cells, each of which splits open at maturity into separate parts and then breaks away explosively, scattering the small seeds.

The family contains a large variety of phytotoxins (toxic substances produced by plants), mainly diterpene esters, alkaloids, glycosides, and ricin-type toxins.

A milky sap or latex is a characteristic of the subfamilies Euphorbioideae and Crotonoideae. This milky sap is poisonous in the Euphorbioideae, but innocuous in the Crotonoideae[citation needed]. White mangrove (Excoecaria agallocha), or Blind- Your-Eye Mangrove sap causes blistering on contact and temporary blindness if it contacts the eyes. Other common names are Milky Mangrove, Buta Buta (Malay), Gewa (Bangladesh). The sap of spurge was used as a laxative.

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Taxonomy and Ebbryology 57

Recent molecular studies have shown that the enigmatic family Rafflesiaceae, which was only recently recognized to belong to order Malpighiales, is derived from within Euphorbiaceae (Davis et al. 2007

BotanicalName:Chamaesycehirta Family:EUPHORBIACEAE commonly known as: asthma plant, common spurge, sneeze weed • Bengali: barokarni, barokherni • Hindi: bara dudhi, duddhi, lal-dudhi

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Ricinus communis

Euphorbia burmanii

A neat rounded, shrubby succulent shrub up to 500mm. The stems are green and cylindrical with no visible leaves. Flowers are yellow-green. Lovely all year owing to its unusual texture and attractive growth habit.

Q.4 Describe characters of family Apocynaceae and it and its Economic importance? Ans Milkweed Family

This is a large The Apocynaceae or dogbane family is a family of flowering plants that includes trees, shrubs, herbs, and lianas.[1] Members of the family are native to Europen, Asian, African, Australian and American tropics or subtropics, with some temperate members. Many species are tall trees found in tropical rainforests, but some grow in tropical dry, xeric environments. There are also perennial herbs from temperate zones. Many of these plants havemilky sap; and many species are poisonous if ingested. Some genera of Apocynaceae, such as Adenium however, have either clear and milky, latex sap, and others, such as Pachypodium, always have clear sap

Characteristics of Family

The dogbane family consists of trees, shrubs, herbs, or lianas with milky sap.

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Taxonomy and Ebbryology 59

The leaves are simple, usually opposite and decussate, or whorled; lacking stipules. Flowers are usually showy, actinomorphic, aggregated in cymose or racemose inflorescences (rarely fasciculate or solitary). They are perfect (bisexual), with a synsepalous, 5-lobed calyx that is united into a tube at the base. Inflorescences are terminal or axillary. Five petals are united into a tube with 4-5 epipetalous stamens. The style is expanded at the apex into a massive clavuncle just below the stigma. The ovary is usually superior,bicarpellary,apocarpous with a common fused style and stigma. The sap of most plants is a milky latex, which is often of economic importance for medicinial use, or for the production of rubber. This sap is often toxic. The Apocynaceae are trees, shrubs or sometimes herbs, usually with milky sap comprising about 200 genera and 2,000 species. The leaves are simple, usually opposite and decussate, or whorled; stipules are usually absent. The flowers are bisexual and actinomorphic or sometimes weakly zygomorphic. The calyx is synsepalous and usually 5-lobed. The corolla is sympetalous and usually 5-lobed. The stamens are distinct, as many as corolla lobes and alternate with them, and adnate to the corolla tube (or perigynous zone). The anthers are introrse and commonly adherent to the surface of the stigma. The gynoecium consists of a single compound pistil of 2 carpels that may be distinct at the level of the superior or rarely partly inferior ovary but which are united by a single style. ovary typically has few to numerous ovules on marginal placentae; when connate, the placentation is axile or intruded parietal. A nectary consisting of 5 glands or an annular ring is usually found at the base of the ovary. The fruit is commonly a follicle, capsule, or berry. The seeds usually are flat and winged or have a tuft of hairs at one end. The fruit is a drupe, a berry, a capsule or a follicle Most parts of many members of this Plant Family are POISONOUS

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Catharanthus pusillus

Key Characters

Flower: Complete, Perfect . Floral Symmetry: Radial. Perianth: +, Differentiated. Calyx (K): 5, Coalescent, Hypogynous. Corolla (C): 5, Coalescent, arising from Perigynous Zone (PZ). Androecium (A): 5, Distinct, adnate to Perigynous Zone or to massive Stigma. Ovary: Superior to sometimes partly Inferior. Placentation: Axile or Parietal. Infloresence: Various. Fruit: Follicles, Berry, or Drupe. Phyllotaxy: Opposite and Decussate or Whorled or rarely Alternate.

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Taxonomy and Ebbryology 61

Leaves: Simple. Stipules: reduced or absent. Other distinctive features: Carpels generally distinct at level of ovary or even up to the single stigma; Sap Milky; Stamens commonly weakly coherent around generally enlarged Stigma or completely adnate to a massive Stigma; Pollen often in paired coherent masses (Pollinia); Corolla appendages or Corona (Crown) often present

Members of this Family usually have:

Simple leaves Milky sap Five part calyx Clusters of flowers Five large petals joined at the base Five stamens

Characteristics of this Plant Family:

Vegetative Characters

perennial herbs, lianas, shrubs, and sometimes small trees often fleshy or woody tubers leaves simple, entire, opposite or whorled stipules lacking or minute sympetalous corolla of 5 lobes colleters at petiole base along with other projections on the perianth tissues have laticifers, sap usually milky nectar accumulates in outgrowths of the stamen-hoods and horns

Reproductive Characters

flowers actinomorphic, perfect, hypogynous to slightly perigynous, and showy fruit a 2 or 1 (by abortion) follicle(s), seeds ovate to oblong with an apical tuft of silky hair superior to slightly inferior ovaries (2 distinct) placentation parietal gynostegium of 5 stamen, 1 stigma but either one connate or two distinct styles flowers rotate, funnelform or salverform

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inflorescence determinate, sometimes appearing indeterminate, occasionally reduced to a singly flower-terminal or axillary

Flowers ~ There is a calyx with five parts, either separate or joined to form a tube. The flowers are in clusters and are often large and showy. They usually have five petals joined into a tube at the base. There are five stamens joined together.

Seeds ~ The seeds capsule has two parts and may be either inside the flower or not. Seeds are very variable, and may be small with a hairy tuft (Nerium) or large and woody (Allamanda

Economic Importance/Fun Facts

most taxa poisonous, many medicinal Catharanthus produces a compound used as an antileukemia drug many ornamentals - bluestar, milkweed, butterfly weed, natal plum, frangipani, periwinkle Apocynaceae are known for poisoning livestock

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Taxonomy and Ebbryology 63

Multiple Choice Question

1. The gynoecium is monocarpellary and placentation is marginal in members of family papilionaceae. 2. When embryo develops from some cell of the embryo sac other than the egg, the process is known as : A) Apospory B) Apogamy C) Parthenocary D) Parthenogenesis 1. Caruncle is a : A) Nucellar Outgrawth B) Inkgumentary outgrowth C) Endosperm Haustoria C) Embryosae Outgrowth 2. A monospric type of embryosac which does not have any antipodals A) Oenothera type B) Polygonum type B) Peperomia type D) Allium type 3. Development of female gamete into a new individual without fertilization is called : A) Androgenesis B) Sporogenesis C) Parthenocary D) Parthenogenesis 4. Name the scientist who first saw the process of fertilization in angiosperms : A) Edward Strasburger B) S.G. Nawaschin C) Gwenda Davis D) M.S. Caves 5. The embryosac formed in the nucellus , is the female gametophyte. 6. The body of orthotropouso vule is upright with micropyle, chalaza and funicle falling in a straight line. 7. The arrangement of ovules in the ovary is called. 8. Allium type of embryo sac is bi sporic and develops from the chalazal dyad. 9. The egg apparatus of peperomia type is characterized by a single synergid 10. Drusa type of embryo sac is characterized by large number of antipodals.

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Key Terms

Actinomorphic radially symmetrical -- used of organisms, organs, or parts capable of division into essentially symmetrical; halves by any longitudinal palne passing through the axis; compare zygomorphic Adnate grown together, used especially of unlike parts Alkaloid any of a very large group of organic bases containing nitrogen and usu. oxyygen that occur esp. in seed plants for the most part in the form of salts with acids (as citric, oxalic, or sulfuric acid), most of the bases being colorless and well crystal lized, bitter tasting, complex in structure with at least one nitrogen atom in a ring (as a pyrole, quinoline, or indole ring), and optically and biologically active, many of the bases or their salts being used as drugs (as morphine and codeine) Alternate arranged first on one side and then on the other at different levels or points along an axial line Ament an indeterminate spicate inflorescence bearing scaly bracts and apetalous unisexual flowers (as in the willow) Anther the part of the stamen in seed plants that consists of microsporangia, develops and contains pollen, and though sometimes sessile, is usually borne on a stalk Anthocarp a fruit with some portion of the flower besides the pericarp persisting, as in a pome with the fleshy perianth tube surrounding the pericarp (h) Apex the pointed end : tip Apical meristem located at the apex of a root or shoot and responsible for increase meristem in length of the organ Areole a small pit or cavity (as that from which spines arise in cacti) Auricle an ear-shaped appendage (as at the base of the leaf blade of many grasses) Apocarpous having the carpels of the gynoecium separate Awn one of the slender bristles that terminate the glume s or bracts of the spikelet in barley, oats, some varieties of wheat, and other grasses Axil the distal usu. upper angle or point of divergence between a branch or leaf and the axis from which it arises Axile belonging to or situated in the axis

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Taxonomy and Ebbryology 65

Axile ovules attached to the central axis of an ovary with two or more ovules (h) placentation Axis the stem of a plant : the longitudinal support on which organs are arranged often including also the root, esp. a taproot : the hypothetical central line of any body or organ Basal proceeding from the base of a stem, from a rootlike stem, or from a stem that does not rise above the ground Berry any simple fruit that has a fleshy pericarp (as the currant, grape, gooseberry, cranberry, tomato, or banana) Biconvex convex on both sides Bilabiate having two lips Bipinnate twice pinnate Bisexual possessing characters typical of both sexes Blade a leaf of a plant esp : a leaf of an herb or more narrowly of a grass c(1) : the expanded portion of a leaf or a plant organ resembling a leaf -- distinguished from petiole (2) : the broad terminal part of certain petals -- distinguished from claw Boreal of, relating to, or constituting a terrestrial biogeographic division comprising the northern and mountainous parts of the northern hemisphere in which mean temperature during the six hottest weeks does not exceed 64.4o F. and being equiva lent to the Holarctic region exclusive of the Sonoran and Transition zones and corresponding Old World areas Buffered in the case of Nymphaeaceae: plants are protected from extreme fluctuations in temperature by the slower rate of change in the body of water (nb) Bulb a mass of overlappiing membranous or fleshy leaves on a short stem base enclosing one or more buds that may develp under suitable conditions into new plants and constituting the resting stage of many plants (as lily, onion, hyacinth, tulip) distingui shed from corm, rhizome, tuber Calyx the outer set of floral leaves making up the external part of the flower and consisting of separate or fused sepals ttha are usu. green and foliaceous but often colored like the corolla -- see corolla Capitulate collected into small capitula (see below) Capitulum a simple racemose inflorescence in which the primary axis is shortened and dilated forming a rounded or flattened cluster of sessile flowers (as in the buttonbush and in all composite plants) -- called also head

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Capsule in seed plants: a dry dehiscent usu. many-seeded fruit composed of two or more carpels and releasing seed at maturity through pores or by breaking into valves--compare pod Chromosome one of the more or less rodlike chromatin-containing basophilic bodies constituting the genome and chiefly detectable in the mitotic or meiotic nucleus that are regarded as the seat of the genes, consist of one or more intimately associated chromatid s functionintg as a unit, and are relatively constant in number in the cells of any one kind of plant or animal Circinate characterized by hor having the form of a flat coil of which the apex is the center -- used esp. of arrangements of plant parts in vernation and of developing fern fronds Circumscissile dehiscing by a transverse fissure around the circumference -- compare loculicidal Claw the slender, prolonged basal portion of certain petals (as in the pink) -- compare blade Clawed having claws (see above) Column the united monadelphous stamens in mallows b : the united androecium and gynoecium in orchids Compound composed of or produced by the union of several elements, ingredients, parts, or things b : involving combination Concave arched in : curving in Cone a mass of ovule-bearaing or pollen-bearing scales or bracts in trees of the pine family and in cycads arranged usu. on a somewhat elongated axis : a carpellate or staminate strobilus; esp : the carpellate strobilus of pine and related trees < b>b : any of several flower or fruit clusters suggesting a cone (as of the hop or certain magnolias) Corm modified underground stem base bearing membranous or scaly leaves and buds and acting as a vegetative reproductive structure in certain monocotyledonous plants (as gladiolus and crocus) -- distinguished from bulb; compare < a href="#tuber">tuber Corolla the inner set of floral leaves that immediately surround the sporophylls, consist of separate or fused petals, and are often highly colored in contrast to the calyx but sometimes inconspicuous or even absent Corona an appendage or series of united appendages borne on the inner side of the corolla in certain flowers (as in the daffodil, jonquil, and milkweed) and often resembling an additional whorl of the perianth Cotyledon the first leaf or one of the first pair or whorl of leaves developed by the embryo in seed plants and in ferns and related plants that functions

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Taxonomy and Ebbryology 67

primarily to make stored food in the endosperm available to the developing young plant but in some cases acts as a storage or photosynthetic organ Creeping tending to spread over the ground or other substrate Cross-shaped . . . two intersecting lines or bars usu. of equal or approximately equal length and crossing at or about their midpoints Crumpled wrinkled, creased, or bent out of shape by or as if by pressing, folding, or crushing Culm the jointed stem of a grass usu. hollow except at the often swollen nodes and usu. herbaceous except in the bamboos and other arborescent grasses; also : one of the solid stems of sedges, rushes, and similar monocotyledonous plants Cyathium an inflorescence consisting of a cuplike involucre with the flowers arising from its base (as in the poinsettia). more... Deciduous falling off or shed at the end of the growing period Decussate arranged in pairs each at right angles to the next pair above and below -- compare brachiate Dehiscence a bursting open: as a (1) : the bursting open of a capsule, pod, or silique at maturity either between the carpels, through the middle of the carpels, or in some other manner -- compare circumscissile, ;loculicidal, septicidal, septifragal (2) : the opening of an anther for the discharge of pollen (as by longitudinal slits or pores) Dehiscent characterized by dehiscence Desert a region in which the vegetation is so scanty as to be incapable of supporting any considerable population (as a region perpetually cold or covered with snow or ice or a region located in the interior of a continent and characterized by scanty rainfa ll esp. of less than 10 inches annually) Determinate growth in which the axis being limited by the devlopment of the terminal flower bud or other reproductive structure does not continue to elongate indefinitely (as in a cymose inflorescence and in certain mosses) Diadelphous of stamens: united by the filaments into two fascicles Dimorphic having two forms Dioecious having staminate and pistillate flowers borne on different individuals Disciform of round or oval shape Disk the central portion of the flower head of a typical composite composed of closely packed tubular flowers

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Disk floret one of the tubular flowers in the disk of a composite plant Dissected deeply divided into many narrow segments (h) Dissepiment a separating tissue : PARTITION : SEPTUM Distinct separate, not attached to like parts (h) Drupe a one-seeded indehiscent fruit having a hard bony endocarp, a usu. fleshy mesocarp, and a thin epicarp like a skin (as in the cherry, plum, and peach) or dry and almost leathery (as in the almond) Drupelet one of the individual parts of an aggregate fruit (as the raspberry) Endemic restricted to or native to a particular area or region : INDIGENOUS -- used of kinds of organisms; compare exotic Endosperm

Entire having the margin continuous or not broken by divisions, teeth, or serrations Ephedrine a white crystalline alkaloid . . . extacted esp. from mahuang or made synthetically and used often in the form of a xalt (as a sulfate) chiefly in relieving hay fever, asthma, and nasal congestion Epidermal of, relating to, or arising from the epidermis [which is] a layer of primary tissue in higher plants that is commonly one cell thick, often cutinized on its outer surface, and continuous in young plants except over the stomata, that provides protecti on to underlying parts against mechanical injury and desiccation, and that is largely replaced (as by periderm or exodermis) in older plants except on leaves and herbaceous stems Epiphyte a plant that grows upon another plant (as a tree) nonparasitically or sometimes upon some other object (as a building or telegraph wire), derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it . . . Episepalous growing on or adnate to the sepals Equitant overlapping each other transversely at the base (as in an iris) Estipulate without stipules Ethereal oil essential oil : any of a large class of volatile odoriferous oils of vegetable origin that impart to plants odor and often other chatacteristic properties, that are obtained from various parts of the plants (as flowers, leaves, or bark) by steam dist illation, expression, or extraction, that are usu. mixtures of compounds (as terpenoids, aldehydes, or esters), and that are used often in the form of essences in perfumes, flavoring materials, and pharmaceutical preparations : volatile oil; distinguished from fatty oil and fixed oil

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Taxonomy and Ebbryology 69

Fleshy receptacle Floret a single flower of a multiple -flowered inflorescence; esp b one of the small individual flowers that make up the head of a comjposite plant -- compare DISK FLOWER, RAY FLOWER Follicle a dry dehiscent one-celled, many-seeded, and monocarpellary fruit (as that of the peony, larkspur, or milkweed) differing from a pod or legume in opening along only one (as the inner or ventral) suture Free not united or combined with something else; distinct, separate Fritillary a plant of the genus Fritillaria Fruit the reproductive body of a seed plant consisting of one or more seeds and usu. various protective and supporting structures Fused mingled, blended, integrated Glochid glochidium : a barbed hair or spine (as on the massulae of a water fern or on some cacti) Glume one of the two empty bracts at the base of the spikelet in grasses Green having the color of growing fresh grass or of the emerald Heterosporous characterized by the production of asexual spores of more than one kind Homosporous characterized by the production by various plants (as the club mosses and horsetails) of asexual spores of only one kind Host a living animal or plant affording subsistence or lodgment to a parasite Husk the outer covering of a kernel or seed esp. when dry and membranous Hygroscopic sensitive to moisture b : induced by moisture Inferior of a part of a plant a : situated below another organ: (1) of a calyx : free from the ovary (2) of an ovary : adnate to the calyx or other floral envelope Latex a milky usu. white fluid of variable compostition that is usu. made up of various gum resins, fats, or waxes and often a complex mixture of other substances frequently including poisonous compounds, this is found in or produced by cells of plants esp of the Asclepiadaceae but also of the Apocynaceae, Sapotaceae, Euphorbiaceae, Papaveraceaea, Moraceae, and Compositae, and that yields rubber, gutta-percha, chicle, and balata as its chief commercial products Locule (loculus) one of the cells of the compound ovary of a plant (2) : the cavity of a pollen sac

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Mericarp one of the two carpels that resemble achenes and form the schizocarp of an umbelliferous plant Mesic of a habitat : having or characterized by a moderate amount of moisture : neither hydric not xeric; of a plant or flora : mesophytic Midvein midrib : the central vein of a leaf Milky sap

Monadelphous united by the filaments into one group usu. forming a tube around the gynoecium Monocarpic bearing fruit but once and dying--used esp. of annual and biennial flowering plants; compare century plant Monocarpous having a single ovary Monoecious having pistillate and staminate flowers on the same plant Monophyletic developed from a single common parent form Monopodial having or involving offshoots from a main axis Motile exhibing or capable of movement Mycorrhiza the symbiotic association of the mycelium of a fungus (as various basidiomycetes and ascomycetes) with the roots of a seed plant (as various conifers, beeches, heaths, and orchids) in which the hyphae form an interwoven mass investing the root tips or penetrate the parenchyma of the root Neuter having no generative organs Node the often swollen or otherwise modified point on a stem or similar structure at which a leaf or leaves are inserted Nucleus an element of the protoplasm of most plant and animal cells that is regarded as an essential agent in their metabolism, growth, and reproduction and in the transmission of hereditary characters and that typically consists of a more or less rounded ma ss of nucleoplasm made up of a hyaline ground substance in which is suspended a network rich in nucleoproteins from which the mitotic chromosomes and one or more nucleoli condense, the whole being enclosed by a nuclear membrane Nut a dry indehiscent one-seeded fruit (as an acorn, hazelnut, or chestnut) with a woody pericarp developing from an inferior syncarpous ovary Nutlet a small nut-like fruit (as of many plants of the family Boraginaceae) Ocrea a tubular sheath around the base of the petiole consisting of a single stipule in the red clover or a pair of coherent stipules in the buckwheat family (Polygoniaceae)

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Taxonomy and Ebbryology 71

Opposite situated in pairs on an axis each being separated from the other by half the circumference of the axis (2) of floral parts : SUPERPOSED (3) situated side by side Ovary the enlarged rounded usu. basal portion of the pistil or gynoecium of an agiospermous plant that bears the ovules and consists of a single carpel or of several united carpels Ovule a rounded outgrowth of the ovary in seed plants that develops into a seed usu. only after fertilization and that consists of an embryo sac borne centrally within a nucellus, the latter surrounded by one or more integuments Panicle a compound racemose inflorescence that is usu. a raceme in which the secondary branches are themselves racemose (as the inflorescence of yuccas) but sometimes merges into the cymose type (as in the horse chestnut) Pappus the appendage or tuft of appendages crowning the ovary or fruit in various seed plants (as composites), being adapted for dispersal of the fruit by wind or other agencies, and consisting of all or part fo the perianth modified into bristles. scales, awns, or short teeth b : the group of bristles formed around the fruit by the calyx of members of the Dipsacaceae, Valerianaceae, and Calyceraceae Pepo an indehiscent fleshy 1-celled or falsely three-celled many-seeded berry usu. with a hard rind (as a pumpkin, squash, melon, and cucumber) that is the characteristic fruit of the famiy Curcurbitaceae Perennial continuing or lasting for several years--used specif. of a plant (as delphinium) that dies back seasonally and produces new growth from a perennating part with both male and female reproductive organs (stamens and pistils); Perfect bisexual (h) Perianth the external envelope of a flower : floral leaves esp. when not differentiated into calyx and corolla Perigynium the saclike bract that subtends the pistillate flower of sedges of the genus Carex and that in fruit becomes a flask-shaped envelope investing the achene Petaloid resembling a flower petal in form, appearance, or texture Petiole a slender stem that supports the blade of a foliage leaf and that is usu. cylindrical but sometimes flattened or even winged Phyllary one of the involucral bracts subtending the flower head of a composite plant

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Phyllode a flat expanded petiole that replaces the blade of a foliage leaf, fulfills the same functions, and is analogous to but not homologous with a cladophyll Pinked with a saw-toothed edge Pinna a leaflet or primary division of a pinnate leaf or frond Pinnate resembling a feather esp. in having similar parts arranged on opposite sides of an axis like the barbs on the rachis of a feather -- used esp. of compound leaves Plumose feathery, plumelike Pollen a mass of microspores in a seed plant appearing usu. as a fine dust made up of minute granular microspores typically formed in fours by reduction of a pollen mother cell with each grain consisting of a single cell that has a characteristicall sculptured outer wall and gives rise on germination to a pollen tube through which its male generative element passes to the ovule for fertilization of the egg Pollinium (pl. Pollinia) the coherent mass of pollen grains that characterizes members of the Orchidaceae and Asclepiadaceae and often has a stalk bearing an adhesive disk that clings to visiting insects and facilitates withdrawal of the whole pollinium from its receptacle Polyphyletic derived (as by convergence) from more than one ancestral line Pome a fleshy accessory fruit (as of an apple) consisting of a central core with usu. five seeds enclosed within a bony or papery capsule made up of fused carpels and of an outer thickened fleshy layer made up of the much enlarged receptacle Pore a minute opening esp. in an animal or plant by which matter passes through a membrane Prickle a sharp pointed emergence arising from the epidermis or bark of a plant Procumbent being or having stems that trail along the ground without putting forth roots Prophyll a plant structure resembling a leaf (as a bracteole) or consisting of a modified or rudimentary leaf (as a foliar primordium) Pulp the soft succulent part of fruit Pulvinus a cushionlike enlargement of the base of a petiole or petiolule consiting of a mass of large thin-walled cells surrounding a vascular strand and functioning in turgor movements of leaves or leaflets by reversible volume changes in the cells Rotate having the parts flat and spreading or radiating like the spokes of a wheel Rust or rust disease : any of numerous destructive diseases of plants produced

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Taxonomy and Ebbryology 73

by fungi of the order Uredinales and characterized by reddish brown pustular lesions on stems, leaves, or other plant parts Saccate having the form of a sac or pouch Samara a dry indehiscent usu. one-seeded winged fruit (as of an ash or elm tree) Sap the fluid part of a plant; specif : a watery solution of gases (as carbon dioxide), salts and other materials from the soil, and organic products of metabolism that circulate through the vascular system, carries raw materials to the periphera l chlorophyll-bearing cells, translocates the products of metabolism to other parts of the plant for use or storage and is a major commercial source of sugar in sugarcane, various palms, and the sugar maple Saprophyte a plant living on dead or decaying organic matter Scale one of the modified leaves serving in most seed plants to protect a bud before expansion . . . b : a thin membranous, chaffy or woody bract . . . d : the small appendage at the base of the petal in some plants of the family Caryophyllaceae e : one of the disklike trichomes making up the characteristic silvery or scurfy pubescence of the foliage in some plants (as Russian olive) Seed the fertilized and ripened ovule of a seed plant comprising a miniature plant usu. accompanied by a supply of food (as endospernm or perisperm), enclosed in a protective seed coat, often accompanied by auxiliary structures (as an aril or caruncle), a nd capable under suitable conditions of independent development into a plant similar to the one that produced it -- see ENDOCARP Seed coat the outer protective covering of a seed that is developed from one or more integuments often in combination with other adherent parts of the ovary (as in a caryopsis) Sepal one of the modified leaves comprising a calyx -- compare PETAL Sepaloid resembling or having the nature of a sepal Septicidal dehiscent longitudinally at or along a septum -- compare LOCULICIDAL> Sorus (pl. sori) a cluster of reproductive bodies or spores on a lower plant: as a : a clump of sporangia on a fertile frond of a fern Spadix a fleshy or succulent spike that is usu. subtended by or enclosed in a leaflike spathe and is the inflorescence characteristic of the arums and palms Spathe a sheathing bract or pair of bracts subtending or enclosing an inflorescence on the same axis exhibiting much variation in form and coloring, and

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occurring typically in plants whose inflorescence is a spadix or in modified form in many monocotyledonous plants (as the irises) Spike an elongated indeterminate inflorescence similar to a raceme but having the flowers sessile on the main axis (as in common plantain) Succulent having fleshy and juicy tissues Superior a : situated above another organ: (1) of a calyx : attached to and apparently arising from the ovary (2 of an ovary : free from the calyx or other floral envelope Tepal any of the modified leaves making up a perianth Thyrse an inflorescence as in the lilac and horse chestmut in which the main axis is racemose and the secondary and later axes are cymose Thyrsoid having somewhat the form of a thyrse Umbel a racemose inflorescence that is characteristic esp. of the family Umbelliferae and has the flower stalks in a cluster arising from a common point at the apex of the main stalk and reaching approximately the same height and sometimes branching again to form secondary clusters Velamen (pl. the thick whitish or greenish multiseriate corky epidermis covering the velamina) aerial roots of an epiphytic orchid and consisting of compactly arranged nonliving cells capapble of absorbing water from the atmosphere Vernation the arrangement of foliage leaves within the bud Verticil a circle or whorl of similar body parts (as flowers about a point on an axis . . . ) Zygomorphic bilaterally symetrical specif : capable of division into esentially symmetrical halves by only one longitudinal plane passing through the axis -- compare actinomorphic

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Taxonomy and Ebbryology 75

Bibliography

Plant Taxonomy

1. www.iapt_taxon.org 2. www.botanik.univie.ac.at

Plant embryology

11. www.wiley.com 12. www.binoz.uj.edu.pl

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