State any two contrivances (Structural adaptations) in flowers which favour cross-pollination.
When the pollen of a flower pollinates the stigma of another flower located on a different plant, whether of the same kind or not, it is called cross-pollination or allogamy.
Structural contrivances which favor cross-pollination are listed below:
1. Dicliny:
Cross-pollination is the rule among diclinous plants, i.e., those bearing unisexual flowers.
2. Self-sterility:
This is the condition when a flower cannot be fertilized by the pollen of the same flower or, sometimes, from a flower of the same strain of plants.
3. Dichogamy:
When stamens and carpels of a bisexual flower mature at different times, pollination between them becomes ineffective.
4. Herkogamy (herkos = barrier):
In some flowers there may be some physical barrier between the anther and the style so that pollination between them is rendered difficult or even impossible.
When the pollen of a flower pollinates the stigma of another flower located on a different plant, whether of the same kind or not, it is called cross-pollination or allogamy.
Structural contrivances which favor cross-pollination are listed below:
1. Dicliny:
Cross-pollination is the rule among diclinous plants, i.e., those bearing unisexual flowers.
2. Self-sterility:
This is the condition when a flower cannot be fertilized by the pollen of the same flower or, sometimes, from a flower of the same strain of plants.
3. Dichogamy:
When stamens and carpels of a bisexual flower mature at different times, pollination between them becomes ineffective.
4. Herkogamy (herkos = barrier):
In some flowers there may be some physical barrier between the anther and the style so that pollination between them is rendered difficult or even impossible.
