11th Class Biology Morphology of Flowering Plants (Root, Stem And Leaf) Cruciferae or Brassicaceae (Mustard family)

Systematic position

        Division      :         Angiospermae

        Class            :         Dicotyledonae

        Subclass     :         Polypetalae

        Series          :         Thalamiflorae

        Order          :         Parietales

        Family         :         Cruciferae (Brassicaceae)

Habit : Annual, biennial or perennial herbs. Farsetia jacquemontii is an undershrub. The plants possess pungent juice having sulphur-containing glucosides.

Root : Tap root alongwith hypocotyl is swollen in Radish (Raphanus sativus) and Turnip (Brassica rapa).

Stem : Erect, cylindrical, hairy or glabrous, herbaceous or rarely woody. It is reduced in the vegetative phase in Radish and Turnip. The stem is swollen in Kohlrabi (Knol-Kohl = Ganthgobi, Brassica oleracea var. gongylodes). Axillary buds enlarged in Brussel’s Sprouts ( = Button gobhi) or Brassica oleracea  var. gemmifera. Brassica oleracea var. capitata (Cabbage) has the largest terminal bud.

Leaves : Radical, cauline and ramal, alternate or sub-opposite but forming rosettes when radical, exstipulate with sheathing leaf base, sessile simple or rarely compound (e.g., Nasturium officinale), hairy. Bulbils occur in the leaf axils of Dentaria bulbifera and on the leaves of Cardamine pratensis.

Inflorescence : Flowers are usually arranged in corymbose racemes. Occasionally they are in corymbs (candituft).

Flower : Ebracteate or rarely bracteate (e.g., Rorippa montana), pedicellate, complete, perfect, regular, actinomorphic, rarely zygomorphic (e.g., Iberis, Teesdalia), tetramerous or bimerous, hypogynous (perigynous in Lepidium), cyclic, cruciform.

Calyx : Sepals 4, polysepalous, aestivation imbricate, generally arranged in two whorls, outer of antero-posterior sepals and inner of lateral sepals, lateral sepals generally saccate or pouched at the base, green or petaloid, inferior.

Corolla : Petals 4, polypetalous, arranged in one whorl and alternate with sepals, often with long claws and spread out in the form of a Greek cross. This arrangement of petals which is characteristic of the family is known as the cruciform arrangement and corolla is described as cruciform corolla, valvate aestivation. Petals reduced or absent in Lepidium and Rorippa.

Androecium : Stamens 6, (four in Cardamine hirsuta, two in Coronopus didymus, 16 in Megacarpaea), free (polyandrous), tetradynamous, arranged in two whorls, outer of two short lateral stamens while the inner whorl is made up of 4 long stamens arranged in two median pairs, anthers basifixed or dorsifixed, dehiscence longitudinal. Green nectaries are often associated with the bases of stamens.

Gynoecium : Bicarpellary (tricarpellary in species of Lepidium, tetracarpellary in Tetrapoma and Tropidocarpum), syncarpous, carpels placed transversely, ovary superior, placentation parietal, ovary bilocular due to the presence of a false septum called replum, style short, stigma capitate, simple or lobed.

Fruit : Siliqua or silicula, lomentaceous siliqua occurs in radish.

Seed : Non-endospermic, often oily.

Floral formula :  Ebr