Wednesday, December 7, 2016

Cruciferae (Brassicaceae) | Family Description | Biology - HSEB Notes

This family comprises about 365 genera and 3250 species. 94 species of 38 genera have been reported in Nepal.

Distribution : The family Cruciferae is cosmopolitan in distribution. Primarily, it is found in temperate zone of northern hemisphere. The plant of this family are cultivated for vegetables, oil yielding seed , ornamental purpose.

Habit : They are mostly herbs which may be annual , perennial , biennial and rarely small shrubs. The plant posses pungent sap having sulfur containing glucoside.

Vegetative characters :

- Root : Tap root and branched. In some species , tap root is modified into napiform(Raphana sativum) and fusiform (Brassica rapa).

- Stem : Erect , herbaceous rarely wooded , branched or unbranched , solid , cylindrical, hairy. The main stem is condensed very much in some sepecies like Brassica rapa , Raphana sativum etc.

- Leaves : Radical , cauline , ramal, alternate , petiolate or sessile , simple , lyrate , unicostate , reticulate venetion , hairy.

Floral characters :

- Inflorescence : Racemose type , generally raceme or corymb or corymboseraceme.

- Flower - Ebracteate , pedicellate , complete , bisexual , actinomorphic and rarely zygomorpohic, tertramerous , cruciform , hypogynous.

- Calyx : Sepal - 4, polysepalous , arranged in two whorls 2+2, inferior , petalloid , imbricate aestivation.

- Corolla : Petal - 4 ,polypetalous, each alternating with carpel , cruciform , valvate aestivation , inferior.

- Androcieum : Stamen - 6, arranged in two whorls 2+4, polyandrous , tetradynomous, outer two short and inner 4 long stamen, green nectrarial gland is present at the base of stamen, anther is dithecious, basifixed, introse.

- Gynoceium : Carpel - 2 , bicarpellary , syncarpous , ovaries : superior , unilocular in the early stage and become bilocular due to developmebt of false septum called replum, style is short and simple , stigma : capitate.

- Pollination : Cross , entomophilous , self sometime.

- Fruit : Siliqua or Silicula.

- Seed : Small , non-endospermic with curved embryo , cotyledon is oily.