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.
Which of the following agents helps in the pollination of Vallisneria and Hydrilla?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Water
Plants use two abiotic agents (wind and water) and one biotic agent (animals) for pollination. Pollination by water is rare. It is found in only about 30 genera, mostly monocots. Vallisneria and Hydrilla are freshwater examples. In Vallisneria, the female flower reaches the water surface on a long stalk, and the male flowers or pollen grains released on the surface are carried passively by water currents to it.
Option (1) Wind — Incorrect. Wind pollination is common in grasses and in maize, where light, non-sticky pollen is carried by air currents. Vallisneria and Hydrilla are aquatic plants whose pollen travels on water, not in the air.
Option (2) Water — Correct. Water carries the pollen in these two plants. This is why they are the book’s examples of water-pollinated plants that grow in fresh water.
Option (3) Birds — Incorrect. Sunbirds and humming birds pollinate some land plants, which usually have large, colourful flowers with nectar. They are not the pollinators of these water plants.
Option (4) Insects — Incorrect. Insects, especially bees, are the main animal pollinators. Many aquatic plants such as water hyacinth and water lily raise their flowers above water and use insects, but Vallisneria and Hydrilla use water.
NCERT Extract:
Pollination – “… Pollination by water is quite rare in flowering plants and is limited to about 30 genera, mostly monocotyledons. … Some examples of water pollinated plants are Vallisneria and Hydrilla which grow in fresh water and several marine sea-grasses such as Zostera. Not all aquatic plants use water for pollination. In a majority of aquatic plants such as water hyacinth and water lily, the flowers emerge above the level of water and are pollinated by insects or wind as in most of the land plants.”