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State any two contrivances (structural adaptations)in flowers which favour cross pollination . |
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Answer» Answer: 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. |
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