Question

Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy.

Answer 1

Dear student,

Autogamy - Here pollen from anther of a flower reaches stigma of same flower and brings about pollination.
Geitonogamy - Here pollen from anther of a flower reaches stigma of another flower in the same plant and brings about pollination.
T​​​​​wo devices in a flowering plant which prevent both autogamy and geitonogamy-
1.The pollen release and stigma receptivity is non- synchronous (Dichogamy).
Dichogamy is the condition where stamens and carpels of bisexual flowers mature at different times. Thus, leaving no option than cross-pollination. Dichogamy is of two types,
a. Protogyny – When gynoecium develops earlier than anthers as in Peepal.
b. Protoandry – When androecium develops earlier than carpels as in pea, sunflower etc.

2. Male and female plants are different (Dioecy). Presence of male and female flowers on different plants, such that each plant is either male or female is called dioecy.

Regards