Why many flowering plants have developed devices to discourage self-pollination? Describe any two such outbreeding devices in plants.

Continued self-pollination leads to interbreeding depression so in order to discourage self-pollination and to encourage cross-pollination, many flowering plants have developed many devices.

Outbreeding devices in plants –

• In some species, the pollen release and stigma receptivity are not synchronised. Either the pollen is released before the stigma becomes receptive or stigma becomes receptive much more before the release of pollen.

• In some other species, the anther and the stigma are placed at different positions so that the pollen can’t come in contact with the stigma of the same flower.

• Some species have self-incompatibility which is a genetic mechanism. When the pollen from the same flower or the other flowers of the same plant falls on the stigma, this mechanism inhibits pollen germination or pollen tube growth in the pistil.