Question

Nontransfer of pollen from anther to stigma of the same flower due to a mechanical barrier is

• A. Dichogamy
• B. Herkogamy
• C. Heterostyly
• D. Cleistogamy

Answer 1

The correct option is B Herkogamy

Dichogamy- It is the condition when the anther and stigma mature at different times. Either anthers dehisce before the stigma becomes receptive (called protandry) or stigma becomes receptive before anthers dehisce (called protogyny).

Herkogamy- It is the condition in which the flower structure is such that even being bisexual, the pollen grains fail to reach the stigma. In some flowers, a mechanical barrier exists between the compatible pollen and stigma so that self pollination is not possible. Sometimes, there is a hood like covering that covers the stigma.

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

Cleistogamy- It is a phenomenon, where flowers never open and in such flowers, only self-pollination occurs within the bud (unopened flower). In such flowers, anthers and stigma lie close to each other. When the anthers dehisce in the flower buds, pollen grains come in contact with the stigma and pollination occurs.

Thus, from all the options given in question, mechanical barrier to prevent the transfer of pollen grains from the anther to the stigma is found in Herkogamy.

So, the correct answer is B.