Biology XI Content
This family compromises about 350 genera and 3250 species. In Nepal, 38 genera and 95 species have been recorded.
Members of this family are cosmopolitan in nature. Majority of species are distributes in temperate-cold region of the world. Many species are used in cultivation and oil-yielding purposes.
- Vegetative characters:
Most of the plants are annual, biennial or perennial herbs, rarely under shrubs. Most of the species are terrestrial and very few are aquatic. Plants possess a pungent smell due to presence of sulphur containing glycosides.
Tap root system, branched. Sometimes roots are modifies into fusiform (Eg. Radish) or napiform to store large amount of food.
Aerial, erect, branched, cylindrical, sometimes stems are represented in the form of disc (highly reduced). Eg. Radish and after the completion of vegetative growth, a long elongated flowering shoot arises from the disc, often glabrous, sometimes pubescent.
Radical (at the base of the root), cauline and ramal, exstipulate, often patiolate, mostly simple, rarely compound, margin entire to dentate, lyrate, in flowering peduncle leaf becomes sub-sessile to sessile progressively upward and possess auniculate leaf , acute apex, unicostate, reticulate venation. FIGURE
- Floral(Reproductive) Characters:-
- Infloresence: Racemose, raceme, eooymbose –carymb
- Flower: Ebracteate, ebracteolale, often pediceclate, actionmorphic, complete, bisexual, tetramerous, hypogynous, superid, often showy, cruciform, hexacyclic
- Calyx: Sepals-4, polysepalous, sepels are arranged in two whorls i.e. 2+2 condition, often succeate, anterior-posterior, pettaloid, imbricute aestivation, caduceus.
- Corolla: Petals-4, polypetalous, cruciform, each petal is differentiated into expanded broad limb and narrow base called as claw, in some plants, two petals become enlarge and thus flower become zygotemorphic, oftem slowly, relvate aestivation, cydic, sometimes petals may be absent or may reduced.
- Androcium: Stamens-6, tetradynamous, orrangedin two whorls, outer whorl consist of 4 longer stameous, number of stamen may be reduced or increased (i.e. 4 stamens only in Nastutium or 16 stamens in Megacarpea), filament long, another dithecous, barifixed or dorisifixed, introse.
- Gynoecium: Bicarpellary, syncarpoces, ovary urulocular at young condition but because bilocular due to development of false septum called as replum, ovary may be trinocular (e.g. Lepidium) or tetralocular (e.g. Tetrapoma), stigma bifid or capitates.
- Fruit: Siliqua or siliculo, sometime fruit is lamentum like siliqua.
- Seed: small, non-endospermic, cotyledons oily
- Pollination: Entomophilous, mostly cross-pollinated, sometimes self pollinated