Question

Cleistogamous flowers are
A. Male female which never open
B. Female flower which never open
C. Bisexual flower which never open
D. Open bisexual flowers which perform self-pollination in bud condition

Answer 1

Cleistogamous flowers are those flowers which only support self-pollination. Self- pollination is a process of transfer of pollen grains from anther to stigma within a single flower.

Complete answer:
1.Self-pollination also called allogamy.It takes place within the same flower.
2.There are some adaptations for self pollination which also includes cleistogamy. The most favourable conditions for self-pollination are as under:

A.Bisexuality: Bisexual flowers ensures self-pollination.
B.Homogamy : It is a condition where stamen and carpel mature at the same time.
C.Cleistogamy: Cleistogamous flowers never open and seed setting in these flowers occur without the exposition of their sex-organs as these flowers are bisexual.

Commelina benghalensis is the striking example of cleistogamy. Other family Violaceae,examples include members of Balsaminaceae and Polygonaceae.
Cleistogamy ensures self-pollination as there are no chances of cross-pollination.
In Commelina benghalensis and Arachis hypogea (groundnut) cleistogamy is accompanied by geocarpy (formation of fruits below the soil).
Commelina has chasmogamous aerial flowers and subterranean cleistogamous flowers.

Hence, the correct answer is option (C)

Note: Advantage/Disadvantage of self-pollination
(a) Self-pollination is almost certain in a bisexual flower. It is an independent process.
(b) Another advantage is purity of generation.