Read the passage and answer the following question:
In flowering plants, the production of male and female gametes occurs within the pollen grain and embryo sac, respectively. Since both types of gametes are immobile, they require a mechanism to be brought together for fertilisation to take place. Pollination is the process that serves this purpose. Pollination refers to the transfer of pollen grains, which are released from the anther to the stigma of a pistil. Flowering plants have developed various remarkable adaptations to accomplish pollination. They rely on external agents to facilitate the process of pollination.
Transfer of pollen grains from the anther to the stigma of another flower of the same plant is which type of pollination?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Geitonogamy
Pollination is named by where the pollen comes from. In autogamy the pollen reaches the stigma of the same flower. In geitonogamy it reaches another flower of the same plant. In xenogamy it reaches a flower on a different plant.
Option (1) Xenogamy — Incorrect. Xenogamy is the transfer of pollen to the stigma of a flower on a different plant. It is the only type that brings genetically different pollen to the stigma.
Option (2) Cleistogamy — Incorrect. Cleistogamous flowers never open. The anthers and stigma lie close together inside the closed flower, so such flowers are always autogamous. Pollen cannot move to another flower here.
Option (3) Autogamy — Incorrect. Autogamy is pollination within the same flower. The question speaks of another flower, so autogamy does not fit.
Option (4) Geitonogamy — Correct. Geitonogamy is pollination between two flowers of the same plant. It needs a pollinating agent, like cross-pollination, but genetically it is like autogamy because the pollen comes from the same plant.
NCERT Extract:
Pollination – “… (ii) Geitonogamy – Transfer of pollen grains from the anther to the stigma of another flower of the same plant. Although geitonogamy is functionally cross-pollination involving a pollinating agent, genetically it is similar to autogamy since the pollen grains come from the same plant. (iii) Xenogamy – Transfer of pollen grains from anther to the stigma of a different plant (Figure 1.9b).”