Tag: pollination and fertilization

In plants, allogamy is used specifically to mean the use of pollen from one plant to fertilize the flower of another plant and are usually synonymous with the term cross fertilization , though the latter can be used more specifically to mean pollen exchange between different plant strains or even different individuals. Allogamy is best favoured by Dicliny. Dicliny refers to unisexual flowers. This is of two types: monoecy and dioecy.

Continous self-pollination or inbreeding leads to inbreeding depression, a condition where the decrease in genetic vigor and vitality results in reduced fitness in offsprings.
Dichogamy is the condition in some flowering plants where the pistils and stamens mature at different times, thus preventing self-pollination.
It is of two types: protandry and protogyny.

Incapability of pollen grains of one flower to grow over the stigma of the same flower due to the presence of similar sterile genes is called self-sterility. Ex: Tobacco, Crucifers, Potato and Gramineae.

Incapability of pollen grains of one flower to grow over the stigma of the same flower due to the presence of similar sterile genes is called self-sterility. Which a leads to emasculation, sexual incompatibility, and cross-pollination.

Cross-pollination is when one plant pollinates a plant of another variety. The two plants' genetic material combines and the resulting seeds from that pollination will have characteristics of both varieties and is a new variety. Self-sterility in plants is enhanced to prevent self-fertilization and increase family diversification. Dichogamy is the ripening of the stamens and pistils of a flower at different times so that self-fertilization is prevented. Herkogamy is a common strategy employed by hermaphroditic angiosperms to reduce sexual interference between male (anthers) and female (stigma) function. Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, exist in the population. All these prevent self-pollination and favour cross-pollination.

Heterostyly is the occurrence of 2-3 types of flowers within the same plant. Such flowers have a difference in length of styles and stamens.

Protandry is the condition when anthers mature before the stigma becomes receptive is called protandry. So, the condition in which the male reproductive organs of a flower mature before the female ones, and hence ensuring that self-fertilization does not occur.

Dicliny is the presence of only one kind of reproductive whorl in a flower.

Herkogamy is the condition in which the flower structure is such that even being bisexual. In some flowers, a mechanical barrier exists and thus self-pollination is not possible. Sometimes, there is a hood for covering the stigma.

So, the correct answer is B.