(a) Mention any four strategies adopted by flowering plants to prevent self- pollination.
(b) Why is geitonogamy also referred to as genetical autogamy?

Explanation

(a)(i)In some species pollen release and stigma receptivity are not synchronised. Either the pollen is released before the stigma becomes receptive or stigma becomes receptive much before the release of pollen.
(ii)In some species the anthers and stigma are placed at different positions so that the pollen cannot come in contact with the stigma of the same flower .
(iii)Self incompatibility is a genetic mechanism and prevents self-pollen (from the same flower or other flowers of the same plant) from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
(iv)Production of unisexual flowers. If both male and female flowers are present on the same plant such as castor and maize, it prevents autogamy but not geitonogamy. In sereval species such as papaya, male and female flowers are present on different plants , that is each plant is either male or female. This condition prevents both autogamy and geitonogamy .
(b)Geitonogamy is referred to as genetical autogamy because the pollen grains come from the same plant.