Plant Taxonomy

Plant Taxonomy Dr. Mohammad Wahsha Introduction • Taxonomy is the science of classifying and identifying plants. • Scientific names are necessary because the same common name is used for different plants in different areas of the world. • Latin is the language used for scientific classification. Identification, classification and description of plants Three goals of plant taxonomy are the identification, classification description of plants. The distinction between these three goals is important and often overlooked. 1.Plant identification is the determination of the identity of an unknown plant by comparison with previously collected specimens or with the aid of books or identification manuals. The process of identification connects the specimen with a published name. Once a plant specimen has been identified, its name and properties are known. 2.Plant classification: is the placing of known plants into groups or categories to show some relationship. Scientific classification follows a system of rules that standardizes the results, and groups successive categories into a hierarchy. For example, the family to which the lilies belong is classified as follows: Kingdom: Plantae Division: Magno-liophyta Class: Liliop-sida Subclass: ...... Series(Order): Liliales Family: Liliaceae Genus: Pine, Wattles, Milk-vetch, Dandelion, etc. Species: Common water Hyacinth, Yellow star-thistle, Purple loosestrife, Kudzu, etc. Variety: ...... The classification of plants results in an organized system for the naming and cataloging of future specimens, and ideally reflects scientific ideas about inter- relationships between plants. The set of rules and recommendations for formal botanical nomenclature, including plants, is governed by the International Code of Nomenclature for algae, fungi, and plants abbreviated as ICN. Title page of Species Plantarum, 1753 3.Plant description: is a formal description of a newly discovered species, usually in the form of a scientific paper using ICN guidelines. The names of these plants are then registered on the International Plant Names Index along with all other validly published names. Carl von Linne (1707-1778) • Swedish botanist • Developed binomial classification scheme for plants. • Uses two Latin words to indicate the genus and the species. • Changed his name to the Latin name of Carolus Linnaeus. Scientific Names • The first word is the genus and the second word is the species. • If there are additional words, they indicate the variety or cultivar. Genus • Plants in the same genus have similar characteristics. • Examples: • Quercus – Oaks • Acer – Maples • Ficus – Figs Species • Plants in the same species consistently produce plants of the same types. Scientific Classification • The broadest category of scientific classification is the Kingdom. • Either Plant or Animal • The broadest category of the plant kingdom is Division or Phylum. Kingdom Phylum/Division Class Scientific Order Classification Suborder Family Genus Species Divisions • The four most important divisions of the plant kingdom are…. • Thallophyte • Bryophytes • Pteriophytes • Spermatophytes 1. Thallophyte The thallophytes (Thallophyta or Thallobionta) are traditionally described as "thalloid plants", "relatively simple plants" or "lower plants". These plants mainly grow in water. They were a defunct division of kingdom Plantae that included fungus, lichens and algae and occasionally bryophytes, bacteria and the Myxomycota (Although presently classified as Protozoans). Thallophytes have a hidden reproductive system and hence they are also called Cryptogamae (together with ferns), as opposed to Phanerogamae. The thallophytes are defined as having undifferentiated bodies (thalli), as opposed to cormophytes (plants differentiated into roots, shoots and leaves, and well adapted for life on land) with roots and stems. It is mainly grow in fresh water and it is fibre like body. 2. Bryophytes Bryophytes are small, non-vascular plants, such as mosses, liverworts and hornworts. They play a vital role in regulating ecosystems because they provide an important buffer system for other plants, which live alongside and benefit from the water and nutrients that bryophytes collect. liverworts mosses hornworts 3. Pteridophyte A pteridophyte is a vascular plant (with xylem and phloem) that reproduces by spores and lacks seeds. Because pteridophytes produce neither flowers nor seeds, they are also referred to as "cryptogams", meaning that their means of reproduction is hidden. The pteridophytes include the ferns, horsetails, and the lycophytes. horsetails ferns lycophytes 4. Spermatophytes • Includes flowering or seed-bearing plants. • The two subdivisions are…. • Gymnosperms • seed-bearing vascular plants, in which the ovules or seeds are not enclosed in an ovary. gymnosperm" comes from the Greek word gymnospermos, meaning "naked seeds". • Angiosperms • are vascular seed plants in which the ovule (egg) is fertilized and develops into a seed in an enclosed hollow ovary. angiosperm's seeds are found in a flower. Angiosperm eggs are fertilized and develop into a seed in an ovary that is usually in a flower. Plant Characteristics Identifying Plants • Physical characteristics are used to identify plants which include…. • Life Cycle • Form • Foliage Retention • Plant Parts • Use & Location Life Cycle • Annuals • Plants that complete their life cycle in one year (such as: Corn, Peas and Watermelon). • Biennials • A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year, the plant grows leaves, stems, and roots (vegetative structures), then it enters a period of dormancy over the colder months. (such as: Leek, Cabbage, Fennel Bulbs). • It will germinate and grow, survive through one winter, and in the second year it will grow more, bloom, and die. Perennials Plants that live more than two years. Perennials, especially small flowering plants, that grow and bloom over the spring and summer, die back every autumn and winter, and then return in the spring from their rootstock, are known as herbaceous perennials. Such as: Apple, Apricot, Strawberry, Tomato, Avocado, Banana and Grape Growth Habits • Trees • Shrubs • Vines Growth Forms • Columnar Spreading Weeping • Pyramidal • Round or Oval Growth Forms Spreading Columnar Weeping Growth Forms Round Oval Pyramidal Foliage Retention • Deciduous • Loses leaves during the dormant season. • Evergreen • Keeps leaves and remains green year-round. Plant Parts – Leaf • Arrangement • Shapes • Color • Vein Pattern • Form – Simple or Compound • Margin • Surface Leaf Arrangement – Simple Leaf Arrangement – Compound Leaf Shape Vein Pattern • Pinnate • Palmate • Parallel • Dichotomous Leaf Margin Leaf Surface •There are 8 common leaf surfaces. • Glabrous • Scabrous • Pubescent • Glaucous • Villous • Rugose • Tomentose • Glandular Leaf Surface – Glabrous • The surface is smooth, not hairy. Leaf Surface – Pubescent • Short, soft hairs cover the surface. Leaf Surface – Villous • Long, straight hairs cover the surface. Leaf Surface – Tomentose • Covered with wool-like hair. Leaf Surface – Scabrous • Covered with short, prickly hairs. Leaf Surface – Glaucous • Covered with a bluish-white waxy substance. Leaf Surface – Rugose • Surface is wrinkly. Leaf Surface – Glandular • Glands filled with oil or resin cover the surface. Plant Parts – Flowers • Color • Shape • Size Plant Parts – Bud & Stem • Shape & Color • Stem Modifications • Thorns • Spines • Prickles Plant Parts – Modified Stems Thorn Prickle Spine Plant Parts – Roots • Tap • Fibrous • Bulb Plant Parts – Roots Tuberous Root Tap Root Fibrous Root Plant Parts – Fruit • Cones • Brambles • Nuts (Acorns) (Raspberries) • Pomes (Apple) • Capsules (Willow) • Drupes (Peach) • Samara (Maple) Plant Parts – Fruit Pomes Cones Acorns Plant Parts – Fruit Drupes Samara Capsules Brambles Use & Location • Not absolute, but helpful. • Indoor or outdoor. • Altitude • Wet or dry • Hardiness Zone • Sun, partial shade, or shade. • Landscape purpose – specimen, border, etc..

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