Types of Outbreeding Devices

There are mainly six types of outbreeding devices that ensure cross-pollination.

1. Dicliny:

In unisexuality, the stamens and carpels occur in different flowers.

2. Dichogamy:

In some bisexual flowers, the stamens and carpels don’t mature at the same time, thereby self-pollination is inhibited.

3. Prepotency:

Pollen grains of another flower germinate on the stigma more rapidly than the pollen grains of the same flower.

4. Self-Sterility:

Pollen grains of a flower don’t germinate on the stigma of the same flower due to the presence of similar self-sterile genes.

5. Heterostyly:

Flowers have different lengths of styles and stamens.

6. Herkogamy:

It is a mechanical device to prevent self-pollination and promotes cross-pollination. In orchids and members of Asclepiadaceae like Calotropis Procera, where the pollens are aggregated in pollinia, the pollination completely depends on the mercy of the insects.