Tuesday, 21 January 2020

Stamen evolution


Androecium
Androecium of the flower is made up of the male reproductive parts i.e. microsporophyll or stamens. It occupies a position outward from the gynoecium and inward from the corolla. But the stamens are sometime inserted on the corolla (epipetalous) and sometime stamens are attached to the pistil (gynandrous). In all perigynous flowers the stamens are inserted on a hypanthium (the calyx-tube and surrounding tissue which gives rise to petals and stamens.)

Each stamens are attached to one another in two general ways- by union of their filaments into on group i.e. monoadelphous
Two groups- diadelphous
Many groups- polyadalphous
Anthers into a ring- syngenesious
Epiphyllous- filaments are remain united with perianth leaves and anthers are free. E.g. Onion
Epipetalous- Filaments are united to petals e.g. Sunflower, potato, Datura, Ipomoea, Brinjal, etc.
Gynandrous- Stamens are united to carpel. E.g. Calatropis, Aristolochia, Cryptostegia
Monoadelphous- filaments form a single tube like structure and anthers remain free. E.g. Azadiracta, Crotalaria, Hibiscus
Diadelphous- filaments fused to form two bundles. E.g. Sesbania, Clitoria
Polyadlephous- filaments are attached to form a number of bundles and anthers remain free. E.g. Citrus, Bombax
Synandrous- anthers remain free and filaments are attached. E.g. Cucurbita
Syngenesious- anthers are attached and filaments are free. E.g. Sunflower, Tridax, etc




















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