Grade 11 Botany BRASSICACEA (Cruciferae) notes and answers

 Brassicaceae (Cruciferae)

Kingdom             : Plant

Division               : Phangerogams                                                             

Class                    : Dicotyledonae

Sub-class             : Polypetalae

Series                   : Thalamiflorae

Order                   : Parietales

Family                  : Cruciferae (Brassicaceae)

 

Genra: 375 and Species: 2500

Distribution: Cosmopolitan (common in temperate region)

Habitat: Terrestrial, cultivated, some aquatic ( Nastrum officinale- watercress, Subularia aquatic- water awlwort)

Habit: Annual (complete their lifecycle in one season), Biennial (complete their lifecycle in two seasons, growing vegetatively and storing food in one season and flowering and fruiting in another season) or Perennial (survive for several years) herbs. Sulphur containing pungent sap due to glucosides (sinigrin)

VEGETATIVE CHARACTERS

Root: Tap and branched (primary root which develops from the elongation of the radicle and bear small radical roots) modified to:  Fusiform (swollen like a spindle, being thickest in the middle and narrowing towards the apex and base Eg: Radish) or Napiform (almost spherical at the base tapering towards the apex Eg: Turnip)

Stem: Erect (vertical and sufficiently strong to stand erect), Herbaceous (doesn’t contain wood), unbranched or branched cylindrical, Pubescent (hairy). The stem becomes very much condensed but after vegetative growth it elongates in the form of floral shoot.

Leaf: Radical (leaves borne at the ground level from a reduced stem eg: Radish), Cauline (leaf born on main stem) and ramal (leaf arises from branches), alternate (successive leaves occur on opposite sides), exstipulate (without stipule), petiolate (with petiole) or sessile (without petiole), lyrate (large terminal lobe and small lateral lobes), unicoastate (strong mid-rib and lateral veins runs parallel towards apex), reticulate venation

FLORAL CHARACTERS

Inflorescence: Racemose (younger flowers are found on tip or center) raceme (main axis is long and bears laterally stalked flowers of equal length) or corymb (main axis is short)

Flower: Ebracteate (without bract), ebracteolate (without bracteolate), pedicellate (having pedicel), complete (have four whorls). Actinomorphic (radially symmetrical), bisexual, tetramerous ( number of floral parts in each whorl is four) , hypogynous ( superior ovary), cyclic ( floral parts arranged in whorls)
CALYX- Sepals 4 in two whorls of 2 each, the outer 2 median and inner 2 lateral, polysepalous(sepals are free from one another), imbricate aestivation (irregular overlapping of sepals and petals)

COROLLA- Petals 4, polypetalous (petals free from one another), aestivation valvate(petals meet by their edges but don’t overlap), imbricate (margins overlap irregularly) or sometimes twisted; cruciform (petals places diagonally in the form of a cross in whorls)

ANDROECIUM- Stamens 6 in two whorls, two outer and four inner, polyandrous (stamens are free from each other), tetradynamous (4 inner long and 2 outer short), anther dithecous (anther having two lobes), basifixed (base of anther and top of filament is joined) or dorsifixed (filament is firmly fixed to back of the anther), introrse(anther facing inward)

GYNOECIUM- Carpels 2 (bicarpellary); syncarpous(carpels are fused laterally to form compound pistil); ovary superior ( gynoecium of hypogynous or perigynous flower) ; unilocular ( single chamber) but becomes bilocular( two chambers) later on due to the development of a false septum called replum; placentation parietal ( parietal arrangement of placenta bearing ovules in ovary)

FRUIT- Silliqua (many seeded) or sillicula (few seeded)

SEED- Small, exalbuminous (seeds with an endosperm) with curved embryo and two cotyledons.

DIAGNOSTIC CHARACTERS

1. Plants have pungent sulphur-smelling sap.
2. Leaves are lyrate.
3. Petals 4, with cruciform corolla.
4. Stamens tetradynamous.
5. Ovary unilocular but becomes bilosular due to development of falseseptum called reptum.
6. Placentation parietal.
7. Fruit silliqua or sillicula.

ECONOMICALLY IMPORTANT PLANTS

 

Scientific Name	Common Name
Brassica oleracea var. capitat	Cabbage ( vegetable )
Brassica oleracea var. botrytis	Cauliflower ( vegetable)
Brassica rapa	Turnip (Local name - salgam) (vegetable)
Brassica campetris	Mustard (Local name- tori) (oil)
Raphanus sativus	Radish (vegetable)
Iberis amara	Candytuft (ornamental plants)
Lepidium sativum	Garden cress (Local name- chamsoor) (medicinal)