Characteristics and economic importance of Cruciferae (Brassicaceae)

1. Diagnostic features

• Herbaceous, exstipulate, alternate leaves.
• Inflorescence- typical racemose type.
• Flowers- ebracteate and bisexual, Calyx-4, freely arranged in two whorls, Corolla-4, cruciform, Stamens-6, tetradynamous.
• Gynoecium: bi-carpellary, syncarpous with parietal placentation.
• Fruit- siliqua or silicula.

2. Distribution

• Worldwide in distribution.
• But they abundantly grow in temperate and cold parts of the northern hemisphere.
• Many species are cultivated for vegetables and oil-yielding seeds.

3. Vegetative characters

a) Habit

• Mostly annual (Brassica), biennial (Raphanus), or perennial (Cheiranthus)
• Mostly herbs, rarely under shrubs (Farsetia)
• Mostly terrestrial and sometimes aquatic (pani sag)
• Parts produce a pungent watery juice having sulfur smell.

b) Root

• Roots are swollen sometimes and modified into various forms due to the storage of reserve food (fusiform and napiform) e.g. radish and turnip.

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c) Stem

• Aerial erect, cylindrical, hairy, branched or unbranched, mostly herbaceous, rarely woody.
• Stem reduced (Brassica rapa, B. napus, and Raphanus sativus).
• Stellate unicellular hairs are commonly present.

d) Leaves

• Cauline and ramal, sometimes radical (Raphanus sativus), exstipulate, alternate, simple, rarely pinnately compound (Nasturtium officinale).
• Margin entire or divided, sometimes dentate.
• Often sessile and auriculate in the floral region. The radical leaves form the rosettes on the reduced stem.
• Lower leaves petiolate and lyrate in some cases, e.g., mustard.
• Venation- reticulate unicostate.

4. Floral characters

i) Inflorescence

• Racemose-raceme, corymb or corymbose raceme.

ii) Flower

• Pedicellate, ebracteate, bracts present in Nasturtium montanum.
• Complete, bisexual, actinomorphic, Zygomorphic in Iberis amara (candytuft), hypogynous, and tetramerous.

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iii) Calyx

• Sepals-4, present in two whorls (2+2)
• Polysepalous, inner lateral sepals saccate (bag-shaped or pouched) at the base.
• Aestivation- imbricate.

iv) Corolla

• Petals-4, free, cruciform (differentiated into claw and limb, diagonally placed).
• Rarely absent (Lepidium), usually equal but sometimes unequal (Iberis amara with large outer petals)
• Aestivation valvate or imbricate.

v) Androecium

• Stamens-6, polyandrous, tetradynamous (2+4) – arranged in two whorls, 2 outer short and 4 inner long.
• The two outer stamens missing in some cases, in some present and in some 16 stamens are present.
• The pair of the outer whorl in a transverse plane alternate with the two longer pairs of the inner whorls in the median plane.
• Anthers are 2- celled rarely 1 celled, introse, dehiscing longitudinally, basi or dorsified.

vi) Gynoecium

• Bicarpellary, syncarpous, superior, unilocular but becomes bilocular due to the development of a false septum or replum.
• Rarely tri-carpellary or tetra carpellary.
• Placentation parietal, ovules 2- many on each placenta.
• Style short, stigma bifid or simple and capitate.

vii)  Fruit

• Siliqua or silicula, sometimes achene like and one-seeded.

viii) Seed

• Contains large embryo, little or no endosperm and cotyledons are oily.

ix) General floral formula

Economic importance

The members of this family are used for various purposes. They are as follows:

1. Food crops

Root of Raphanus sativus (radish), Brassica rapa (turnip), stem of B. caulorapa (vern. Gyanth gobi), leaves of B. oleraceae var. capitata cabbage, B. juncea (rayosag) and inflorescence of B. oleraceae var. botrytis (cauliflower) are used as vegetables.

2. Oil

Brassica compestris (sarson), B. napus (tori), B. rapa (turnip), etc are used for extraction of oils.

3. Spices

Seeds of B. nigra (black mustard), B. hirta (white mustard) and B. juncea (indian mustard) are used as spices.

4. Medicines

• Seeds of Iberis amara (candytuft), Rorippa indica are used in asthma.
• The flowers of Cheiranthus cheiri are used to cure mild paralysis and its seeds are used for curing bronchitis, fever and eye injuries.

5. Ornamentals

• Some species are used as ornamental plants in the garden.
• These are Iberis amara, Cheiranthus, Arabis, Hesperis, Lunaria, Mathiola incana, Nasturtium, etc.

References:

i) https://www.reed.edu/biology/courses/bio332/PlantFamily/family_info/Brassicaceae.html

ii) https://www.studyandscore.com/studymaterial-detail/brassicaceae-general-characters-distribution-important-plants-economic-importance-and-floral-diagram

Characteristics and economic importance of Cruciferae (Brassicaceae)