Outbreeding Devices

Plants have many mechanisms and devices that they employ to promote cross-pollination. Let us look at a few of them in  the following segments:

Unisexuality: In this case, the plant bears either male or female flowers and is not hermaphrodite. It is also called as Dioecism.

Dichogamy: In this mechanism, the stigma and anther mature at different times. Depending on who matures first, dichogamy can be further divided into two:Protandry: In this type, the androecium matures earlier than the gynoecium. Ex: maize plantProtogyny: In this type, the gynoecium matures earlier than the androecium.

Herkogamy: This is a name given to a condition where there is a natural physical barrier that prevents the pollen of the same flower from entering the ovary.

Self- Sterility: In this condition, there is a gene that recognizes the similar gene and does not allow the pollen grain to germinate. This is due to the self-sterile gene present in the ovule and the grain

Heterostyly:  In some plants like the oxalis, the stigma and the anthers are placed at different levels. This prevents the pollen from reaching the stigma and pollinating it. 

Pollen prepotency: In this mechanism, the pollen of a different flower germinates faster than of the same flower thus preventing autogamy.

Kuch plants self fertilisation na ho bolkar Kuch aisa mechanism adopt karte hai in short they adopt Some mechanism to prevent self fertilisation