BIOLOGY NEET NOTES PDF-FAMILIES OF ANGIOSPERM
CRUCIFERAE (BRASSICACEAE) MUSTARD FAMILY)
Distinguishing Features of Cruciferae –
The plant organs have pungent odour. This odour (BIOLOGY NEET NOTES PDF) is due to presence of sulphur containing glucosides compound. Myrosin enzyme (present in secondary cells) hydrolyse then into glucose & different isothiocyanates (Various oils).
Inflorescence – Typical raceme.
- Iberis amara = Candytuft (chandni) has corymb type of inflorescence.
- The compound corymb inflorescence is present in cauliflower.
- Corymbose raceme inflorescence is present in mustard.
The common Characteristics of flower – (BIOLOGY NEET NOTES PDF)
- Bisexual or hermaphrodite
- Actinomorphic but some time zygomorphic e.g. Iberis amara
- Hypogynous and tetramerous,
- Calyx- Sepals 4, polysepalous, sepals arranged in two whorls 2 outer and 2 inner. Imbricate or valvate or quincuncial aestivation.
- Out of their four sepals two lower sepals are small and apper two are big in size
Corolla– Petals 4, polypetalous, valvate aestivation and cruciform.
- The each petal in cruciferae is divided into two parts-long claw and broader lamina-limb.
- The corolla is absent in Lepidium and Coronopus.
- The corolla is transformed into stamens in Capsella. Androecium :- Stamens 6 (2 + 4), Tetradynamous. Nactaries are present at the base of the anthers * Exception – 2 stamens in Coronopus, 4 stamens in Lepidium and Cardamine, and 16 stamens in Megacarpea.
Gynoecium – Bicarpellary, syncarpous.
- The ovary is unilocular in the beginning but it becomes bilocular due to the formation of a false septum (replum),
- Placentation is parietal.
- Both the carpels arranged transversely.
- Gynoecium is tricarpellary in Lepidium, and tetracarpellary gynoecium in Nasturtium
Fruit –Usually siliqua which is solitary dry and dehiscent.
Silicula fruit is found in Capsella, Iberis, Lepidium and Alyssum.
Seed – Non endospermic