PLANT BIOLOGY By Julius V. L

1. PLANT BIOLOGY By Julius V. L

2. What is a plant??? A plant is a member of the kingdom known as plantae and consists of organisms that produce their own food through photosynthesis, are typically non-mobile, do not have sensory organs (i.e., ears and eyes), brains, nor a central nervous system. Examples of plants would be grasses, trees, vines, etc.

4. 1. PLANT CLASSIFICATION TAXONOMY , NOMENCLATURE AND IDENTIFICATION TOOLS/KEYS Meaning of classification It refers to ordering of organisms into groups, based on similarities and/or differences. It refers to the assigning of plants to groups within a system or hierarchy of ranks or categories distinguished by structure origins and other characteristics. It is both a process and an object. As a process it is the production of logical system of categories each containing any number of organisms which allows easier reference to its components

5. PLANT CLASSIF. CONT • Taxonomy. • Plant taxonomy may be defined as the study and description of the variation of plants, the investigation of the causes and consequences of this variation, and the manipulation of the data obtained to produce a system of classification.It is the branch of botany that deals with identifying naming and classifying organisms (plants) and trying to sort out natural relationships.

6. . PLANT CLASSIF. CONT • Nomenclature. • This is the studyof the system and methods of naming plants. It includes the construction, interpretation and application of the regulations governing the system. In naming plants special international rules must be achieved. For plants, fungi, slime moulds and green-blue algae we use the International Code of Botanical Nomenclature (ICBN).

7. PLANT CLASSIF. CONT • Nomenclatural rules • Family names must end with -aceae, except for old names. • Every family name must begin with capital letter and not underlined. • Generic name must begin with a capital letter and is always underlined or italicized. • The species name also called species epithet is always underlined or italicized but never begins with a capital letter. • . The genus and species names together are known as binomial

8. PLANT CLASSIF. CONT Nomenclature cont. • Species refer to a population of individuals capable of freely inter-breeding in nature but not generally interbreeding with members of another species. • Because of two names contained in scientific names we refer them, as binomials and therefore the method of naming become known as the binomial system of nomenclature. Today all organisms are named according to this system.

9. PLANT CLASSIF. CONT • Writing scientific names. • A scientific/botanical name of a specimen consists of two parts; • A generic name – referring to the genus to which a specimen belongs. • A species name/epithet – referring to the species of a particular specimen. • The two make what we refer to as binomial. Generic name start with a capital letter, species lower case letter ,all the two are separately underlined or italicized.

10. PLANT CLASSIF. CONT • Writing scientific names • Example; • Mangiferaindica is a scientific name for the mango tree. In this case Mangifera is the genus to which the mango tree belong and indica is its species epithet. Alternatively the name can be italicized and appear as Mangifera indica. All the two forms are acceptable in the scientific world.

11. PLANT CLASSIF. CONT • Systematics/systematic biology This is a scientific study of the diversity of organisms. It attempts to understand the evolutionary relationships among the ordered plant groups, and also the process of evolution itself.

12. PLANT CLASSIF. CONT • Identification/determination • Naming of an individual plant specimen by referring to an already existing classified and named group. • Taxon (taxa) refers to any taxonomic grouping e.g. Kingdom, Division, Class, Order, Family, Genus, Species, etc. • In taxonomy we use taxonomic characters; i.e. Characters or features (qualitative or quantitative) that can occur in two states. It is a feature of an organism that is divisible at least into two conditions/states and that is used for constructing classification and associated activities, principally identification.

13. PLANT CLASSIF. CONT • Identification/determination cont. • A character of an organism refer to all features/attributes possessed by the organism that may be compared, measured, counted, described or otherwise assessed, e.g. corolla shape in angiosperms (bell-shaped, funnel form, or bilabiate = state of the character); leaf arrangement (alternate, opposite and whorled = state of the character).

14. PLANT CLASSIF. CONT. • Classification of the plant kingdom • There are several taxonomic groups (taxa) in the classification hierarchy. The plant Kingdom is further divided into Divisions. The Division is divided into Classes. The taxonomic hierarchy is shown in the next slide. The different groups and categories give distinctive levels of organization of the plant Kingdom

15. PLANT CLASSIF. CONT Classification of the plant kingdom cont. Taxon or CategoriesRemarks. • Kingdom Plantae- Plant kingdom • Division A group of related classes. • Class A group of related orders. • Order A group of related families. • Family A group of related genera. • Genus A group of related species. • Species A group of related individuals with related physical form and which can interbreed . freely in nature

16. PLANT CLASSIF. CONT • The plant Kingdom: There are four divisions • Bryophyta: Mosses (Musci) and liverworts (Hepaticae) and hornworts (Anthocerotae). They are found in wet banks, on soil, rock surfaces, some are epiphytes and others are aquatic. • Pteridophyta: The ferns, horse tails, club mosses. They are structurally complex and reproduce by means of spores. • Gymnosperms: Conifers and their allies. They bear naked seeds i.e. the seed is not enclosed in an ovary. Pines and firs are such plants. • Angiosperms: Flowering plants with ovules (seeds) borne within a closed cavity (ovary)

17. 2. PLANT COLLECTION AND PRESERVATION TECHNIQUES • Botanical resources consist of but not limited to herbaria, botanic gardens and arboretums. Herbaria (herbarium) refer to libraries of dried and pressed plants arranged so that specific plants are easily retrieved. The mechanism behind drying is to reduce the moisture content of plants parts as quickly as possible, with a minimum distortion using plant press.

18. PLANT COLLECTION cont. • Herbarium is a data store in which information about plants is stored mainly in the form of a collection of dried, pressed plants mounted on sheets bearing a detailed data label, and stored in strong cupboards in a systematic sequence

19. PLANT COLLECTION cont. • Some preservations which cant be mounted on paper also exists e.g. spirit preserved specimen (fleshy plants or organs); boxes or trays of bulky dried materials (e.g. timber, bark, large fruits); drawings; paintings and photographs and microscope slides of anatomical and cytological preparations.

20. PLANT COLLECTION cont • Herbariums offer the following main services: • Identification of specimens (by comparison) • The basis for research and the preparation of floras and monographs – researchers preparing floras and monographs extracts most of their data from herbarium materials. • Teaching – botany • Preparation of voucher specimens – it is a focal point of taxonomic research

21. PLANT COLLECTION cont. • How to collect plant specimen. • What to collect. • Specimen must be as complete as possible. Collect the whole plant if it is a small sized species or much material to show many characters possible for larger plants. • Obtain flowering and fruiting material of each plant species collected. • Avoid sterile materials as far as possible. • NB: a good collector is the one with small collection of really good specimens carefully pressed to show all the required details rather than large and untidy collection of scraps.

22. PLANT COLLECTION cont • Collect when dry and not wet with dew to avoid moulding of specimens when preserved. • How to put specimens in press. • The purpose is to flatten the specimen and dry the plants as quickly as possible. Speed is important as color is retained in those specimens which can be dried quickly. The collected plant should be arranged in the paper so as to look as natural as possible, with leaves flattened and flowers displayed to show different views, the kind of inflorescence etc.

23. PLANT COLLECTION cont • Collect several specimens of each species so as to be duplicates. • How to collect • Collection methods vary from individual to individual and there is no universally acceptable method of plant collection. The following guidelines are going to guide us in collection work. • Select an area of undisturbed vegetation go over the ground carefully and slowly’ spotting plants at their different stages of growth, and finally collect a few specimens at a time.

24. PLANT COLLECTION cont • . Large flowers, fruits, roots, etc. can be cut in half before being pressed and surplus leaves can be removed. Succulent plants must be killed by immersing in methyl spirits, alcohol for an hour, paraffin or in boiling water for 5-10 minutes before it is pressed to retard their growth. For thorny species their thorns/spines have to be broken or bent so that they do not destroy other specimens.

25. PLANT COLLECTION cont • How to dry specimens. • Keep the press in warm place. To reduce the drying times alternate the drying papers with a piece of corrugated paper in the press so as to allow warm air to circulate through the press. Avoid too much heat as it can bake the plant hence becoming extremely brittle and difficult to mount or examine when dry.

26. PLANT COLLECTION cont • Note: A very serviceable plant press can be made from easily available materials. Good frames can be easily made from weld-mesh cut to about 31cmX46cm. The frames can be tied with rubber bands cut from inner tyre tubes. A good supply of old newspapers alternating with corrugated paper will act as drying papers. Specimens dry much more quickly if not too many are put in one press

27. PLANT COLLECTION cont. • Field notes. • Make notes about each plant collected in a field notebook when the plant is collected. These will be transferred to a mounted and preserved specimen. The field notes should consist of:

28. PLANT COLLECTION cont • Flora of ……name of the country and region • Name... if not known leave the place to fill latter. Vernacular name+ the language from which it comes. • Economics…its uses in the area • Locality…village/river etc.….Altitude…at least approximately in meters • Habitat…vegetation type.. • Description…growth form, annual/perennial etc. • Date…collection date • Collected by…name+ initials of collector .No. …collector number.

29. PLANT COLLECTION cont • How to mount good specimens. • The mounter must display the specimen on the mounting sheet to show as many features as possible. He/she must make use of the mounting paper as much as possible. The following can give you good results in mounting

30. PLANT COLLECTION cont 1. The specimen should not exceed the borders of the paper. 2. Specimens should not overlap each other when mounting more than one specimen on the same sheet. 3. Ensure fruits, flowers and leaves are properly stuck on the sheet. 4. For grasses stick the floral parts carefully so that all do not lay loose on the sheet. 5. Place the herbarium labels and the collector’s field notes at the bottom right hand side of the sheet.

31. PLANT COLLECTION cont 6. Divide and mount large specimens in two different sheets but each should show different features of the specimen. 7. When poisoning be careful not to apply the poison on the labels as it will erase the notes. 8. Use glue only when necessary. 9. The specimen should be assigned family numbers by the responsible person so as to aid in their easy location.

32. 3. PLANTS GROWTH FORMS • Plants are classified taxonomically into families, genera, species, varieties, etc. This, however, is not the only way to classify plants. Species and individuals can be grouped into life form or growth form classes on the basis of their similarities in structure and function.

33. A plant life form is usually understood to be a growth form which displays an obvious relationship to important environmental factors. • E.g. a deciduous tree is a plant life form that responds to an unfavorable season by shedding its leaves.

34. WOODY PLANTS:Approaching the nature of wood;usually applied to perennial plants whose stems do not die back at the end of growing season.Includes the shrubs and trees. • Shrubs:A perennial woody plant usually two or more stems arising from or near the grounds. Differ from tree in that it is small and does not posses a trunk eg:,hibiscus. • Trees:Perennial plant having an upright woody main stem, and usually the tallest of plants at maturity. A tree differs from a shrub in that it usually produces a single, well-defined main stem, or trunk, and from a herbaceous plant in that the stem is composed almost entirely of woody tissue.Plants which are tall and have hard and thick brown stem are called trees.eg:redwood tree,oak tree.

35. HERBACEOUS PLANTS; non-woody,soft and leafy,with a stem that dies back to the ground each year.Includes herbs and grasses. Grasses:The distinctive feature of grass is the presence of the sheath and ligule. The sheath encircles the stem and gives support to the area just above each node .The ligule is a short hairy or membranous projection at the point where the leaf sheath joins the leaf blade.

37. Herbs:A plant which does not develop persistent woody tissues(non-woody) above the ground and either dies at the end of growing season or overwinters by means of underground organs( rhizomes,bulbs,corms:eg:ginger,garlic ,mustard,pepper) Other types of plants are creepers and climbers. • Plants with weak stems that cannot stand upright and spread on the ground are called creeper .eg:pumpkin,grapes. • Plants that take support on neighbouring structures and climb up are called climber.

38. MORPHOLOGICAL FEATURES OF PLANTS Defn: Plant morphology (or phytomorphology) • is the general term for the study of the morphology (physical form and external structure) of plants. • Plant morphology is useful in the identification of plants.

39. Application of plant morphology • Use in identificationPlant biologists use morphological characters of plants which can be compared, measured counted and described to assess the differences or similarities in plant taxa and use these characters for plant identification, classification and descriptions.When characters are used in descriptions or for identification they are called diagnostic or key characters which can be either qualitative and quantitative.

40. 1. Quantitative characters are morphological features that can be counted or measured for example a plant species has flower petals 10-12 mm wide. 2. Qualitative characters are morphological features such as leaf shape, flower color or pubescence. • Both kinds of characters can be very useful for the identification of plants.

41. Morphological features of Plant

42. BASIC PARTS OF PLANT The plant body consists of two basic parts: the shoot systemand the root system. Shoot system composed of stems and leaves, and a root system are the vegetative parts of vascular plants. These two systems are common to nearly all vascular plants. The shoot system includes organs such as leaves, buds, stems, flowers, and fruits and usually it develops above ground. The functions of the shoot system include • Photosynthesis, • Reproduction, • Storage, • Transport, • Hormone production.

43. BASIC PARTS OF PLANT cont.. • The root system,root is a part of a plant body that bears no leaves, and therefore also lacks nodes. Root system includes roots as well as modified stem structures such as tubers and rhizomes and usually it develops underground. But roots can also be aerial (they are mainly for absorption e.g epiphytic orchid (Oncidium spp. Epiphytic plants grow on other trees using them for support. Their aerial roots rarely reach the soil so absorb water from rain or mist) or aerating (growing up above the ground or especially above water). • The roots of most vascular plant species enter into symbiosis with certain fungi to form mycorrhizas, and a large range of other organisms including bacteria also closely associated with roots.

44. BASIC PARTS OF PLANT cont.. Basic functions of the root system include • Anchorage of a plant body to the ground, • Absorption of water and mineral solutions, • Storage of water and food, • Transport of materials and • Production of certain hormones

45. STEMS • The stem is usually the part of a plant shoot that bears the leaves at regular intervals, buds and flowers. • It is the main trunk or frame of the plant • Normally develops from the plumule of the axis of the embryo and grows vertically • Some stems are thin and weak and have to climb on other plants, some are stout and thick as in trees.

46. External features of the stem • Stem consist of the blade, the expanded portion of a leaf, which is attached to a stem by a petiole. • Nodes, the regions of a stem where leaves attach, are separated by internodes. • Leaf scar a layer of cork that seals the scar left after leaf fall. E.g in Papaya • Leaf axil -the area just above where the leaf is attached. Angle between leaf stalk and stem

47. STEMS cont… • Terminal bud/Apical bud is either a vegetative or floral bud at the tip of the plant. It is the main growing point of the shoot. • Axillary buds are located in the upper angles of leaves/leaf axil. Most of these axillary buds are dormant, but they have the potential to develop into vegetative (leaf-bearing) branched or flowers.

48. Classification of stem • Aerial stems-stems that grow above the soil eg in trees, shrubs and grasses • Subterranean stems- stems that grow underground eg rhizomes, tubers, bulbs and corms • Climbing stem- eg grapes • Prostrate stem- lie horizontally on the ground eg Tridax procumbens

49. Types of stem cont.. • The stem can also be: • Wood or • Herbaceous • A stem is termed herbaceous if made up of soft tissue, green and with naked buds which are active throughout their life and are not capable of increasing their diameter with growth ie not undergo secondary growth, they are annual plants eg grasses and herbs

50. Woody stem are thicker, hard, strong composed chiefly of xylem, usually covered with the bark with rough texture and lacks the green colour. they are perennial eg shrub and trees