M.SC SEM II :MBOTCC 9, PRACTICAL( VIRTUAL LAB E –CONTENT ) FACULTY MEMBER : Dr Tanuja, University Department of Botany,Patliputra University Aim: Study and describe flowering plant of family Crucifeare(Brassicaceae) Principle: Taxonomy deals with identification, nomenclature and classification of organisms. Bentham and Hooker's system of classification is universally used for classification of plants. Field identification of plants is based primarily on morphological features particularly the floral characters. Requirement: Locally available plant specimen of cruciferae. Each specimen should have at least a small branch with a few inter nodes, leaves, flowers and fruits; glass slides, cover glass, water, 100 ml beakers, petridish, razor, blade, needles, brush, hand lens, dissecting microscope and compound microscope. Keep the twigs in beakers containing water. Make yourself familiar with the terms given to describe the habit of plant, its root system, stem and leaf, inflorescence and flowers. Describe the vegetative and floral features of the plant in the same sequence using terms described therein. Observe the flower bud under dissection microscope or a hand lens and note the aestivation patterns of calyx and corolla, number of sepals and petals (tri, tetra, pentamerous), number of stamens. Cut LS of the flower, place it on a slide and observe under the dissecting microscope to study: •• • • • Position (attachment) of stamens – opposite/alternate to petals; free or epipetalous; extrorse/ introrse anthers (anther lobes in the bud face away from axis – extrorse; anther lobes in the bud face towards the main axis – introrse). • • •• • Number of carpels (mono, bi, tri- carpellary); Position of the ovary (epigynous, perigynous, hypogynous). Mount a stamen on a slide and study the attachment of filament to anther (basifixed, dorsifixed, versatile, adnate), dehiscence pattern of anther (porous, longitudinal), number of anther lobes (monothecous, dithecous). Mount the pistil and study the ovary, style and stigma. Also cut a TS of the ovary to study the number of locules and placentation. Write the floral formula and draw the floral diagram of each specimen based on the description. Systematic position: Family – Cruciferae (Brassicaceae) (Mustard Family): Distribution: It includes 350 genera and about 3000 species. The members of the family are cosmopolitan but majority of the members are found in north temperate region. Habits: Plants are annual, biennial or perennial herbs. Root: Roots are usually tap and branched. Several modifications of tap roots arc found such as fusiform (in Raphanus sativus), conical (in Radish) and napiform (in turnip-). These modifications mainly serve to store the food materials. Stem: Herbaceous, erect, cylindrical, usually reduced or condensed (in turnip and radish etc.). Leaf: Simple, alternate, exstipulate and possess simple or branched hairs. Leaves are usually radical or cauline, sub-sessile or sessile lyrate. Radical roots are found in rosettes. Sometimes bulbils are born in the axils of upper leaves which are used for vegetative reproduction. Inflorescence: Racemose and usually raceme. Flower: Ebracteate, regular (actinomorphic), pedicillate, complete, hermaphrodite, tetramerous, cruciform and hypogynous. Calyx: 4 sepals, polysepalous, arranged in two whorls of two each. The inner lateral sepals are sometimes pouched at the base and serve as nectar containers. Aestivation is imbricate. Corolla: Petals 4, polypetalous, cruciform arranged in a single whorl. These are alternate to the sepals. Each petal is differentiated into a narrow claw and a broad expanded limb, valvate. Androecium: 6 stamens, arranged in two whorls of 2 and 4. Outer two stamens are short and inner 4 stamens are long, (tetradynamous). At the base of the outer two short stamens are present green glands or nectaries. Anthers are bilobed, basifixed and introse. Gynoecium: Bicarpellary, syncarpous, superior ovary, unilocular, but becomes bilocular (due to the development of false septum or replum from the ingrowths of the parietal placentae). Placentation is parietal. Ovules are anatropous or campylotropous. Style is short with bilobed stigma. Fruit: Siliqua or silicula. Sometimes it is lomentum (Raphanus sativus). Seed: Small, exalbuminous (non endospermic), with large curved embryo. Testa is mucilaginous. Economic Importance of family: i. Vegetable yielding plants: Mustard (Brassica campestris), Cabbage (Brassica oleracea var capitata), Cauliflower (Brassica oleracea var botrytis), Radish (Raphanus sativus). ii. Oil yielding plants: Brassica campestris, Rye (B .Juncea) Blackmustard (B. nigra), While mustard (B. alba) etc. iii. Medicinal plants: Sisymbrium officinale, Nasturtium indica, Eruca sativa, Lepidium sativum. iv. Ornamental: Candytuft (Iberis amara), Wall flower (Cheiranthus). Important Plants: i. Mustard (Brassica campestris) ii. Cabbage (Brassica oleracea var capitata) iii. Cauliflower (Brassica oleracea var botrytis) iv. Radish (Raphanus sativus) v. Rye (Brassica juncea) vi. Candytuft (Iberis amara) .