Sexual Reproduction in Flowering Plants

Study Notes

Observe flowers of various plants (e.g., Cucumber, Mango, Peepal) to identify visiting animals and potential pollinators.
Characteristics of a flower are linked to the visiting animal.
Only animals contacting anthers and stigma can cause pollination.
Some insects (pollen/nectar robbers) consume pollen or nectar without pollinating.

Most flowering plants have hermaphrodite flowers, increasing the likelihood of pollen contacting the same flower's stigma.
Continuous self-pollination leads to inbreeding depression.
Plants have developed devices to discourage self-pollination and encourage cross-pollination.

Some species have unsynchronized pollen release and stigma receptivity to prevent self-pollination.
Anther and stigma positions can prevent autogamy by making pollen-stigma contact impossible.
Self-incompatibility prevents self-pollen from fertilizing ovules by inhibiting pollen germination or pollen tube growth.
Production of unisexual flowers prevents self-pollination (e.g., castor, maize).
Dioecy (male and female flowers on separate plants) prevents both autogamy and geitonogamy (e.g., papaya).

Pollination doesn't guarantee compatible pollen transfer.
The pistil recognizes compatible or incompatible pollen and accepts or rejects it accordingly.
If compatible, the pistil promotes post-pollination events.