Describe the three types of pollination that can occur in a chasmogamous bisexual flower.
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Solution and Explanation
A chasmogamous flower is a flower that opens at maturity, exposing its reproductive parts.
A bisexual flower contains both stamens (male organs) and carpels (female organs).
In such flowers, three types of pollination are possible:
1. Autogamy (Self-Pollination)
Definition: Transfer of pollen from the anther to the stigma of the same flower.
Requirements: Proximity of anthers and stigma, and synchronization in their maturation.
Advantage: Ensures seed formation even in the absence of pollinators.
Limitation: No genetic variation.
🌱 Example: Wheat, Pea
2. Geitonogamy (Functionally Cross-Pollination)
Definition: Transfer of pollen from the anther of one flower to the stigma of another flower on the same plant.
Mechanism: Requires pollinating agents like insects or wind.
Genetically: It is self-pollination since the plant is the same.
Functionally: It mimics cross-pollination as it involves a vector.
🌻 Example: Maize, Cucurbits
3. Xenogamy (True Cross-Pollination)
Definition: Transfer of pollen from the anther of a flower on one plant to the stigma of a flower on a different plant of the same species.
Results in: Maximum genetic variation.
Requires: External pollinators (wind, insects, water, animals).
🌼 Example: Apple, Sunflower, Hibiscus
Summary Table
| Type | Source of Pollen | Genetic Effect | Pollinator Needed |
|---|---|---|---|
| Autogamy | Same flower | No variation | Not needed |
| Geitonogamy | Same plant | No variation | Yes |
| Xenogamy | Different plant | High variation | Yes |
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