Question

Explain Cleistogamy?

class 12th CBSE Biology sample paper

Answer 1

In some plants, flowers never open.
In such flowers, anther and stigma lie closed to each other and thus ensure self-pollination on maturity.
These cleistogamous flowers produce assured seed-set even in  the absence of pollinator.
Some plants like Viola (pansy), Oxalis and commelina produce both types of flowers i.e., open chasmogamous and closed cleistogamous flowers.
Cleistogamy occur in late flowering season.

Answer 2

Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas, and beans, this behavior is most widespread in the grass family. However, the largest genus of cleistogamous plants is Viola.

The more common opposite of cleistogamy, or "closed marriage," is called chasmogamy, or "open marriage." Virtually all plants that produce cleistogamous flowers also produce chasmogamous ones.  The principal advantage of cleistogamy is that it requires fewer plant resources to produce seeds than does chasmogamy, because development of petals, nectar and large amounts of pollen is not required. This efficiency makes cleistogamy particularly useful for seed production on unfavorable sites or adverse conditions. Impatiens capensis, for example, has been observed to produce only cleistogamous flowers after being severely damaged by grazing and to maintain populations on unfavorable sites with only cleistogamous flowers. The obvious disadvantage of cleistogamy is that self-fertilization occurs, which may suppress the creation of genetically superior plants.