Their reproduction depends on water for spore germination and fertilisation.
Explanation
Non-flowering plants such as mosses (Bryophytes) and ferns (Pteridophytes) are classified as cryptogams. Unlike gymnosperms and angiosperms, these plants do not produce seeds or flowers. Their distribution is largely restricted to moist and shaded terrestrial environments due to specific evolutionary constraints in their life cycle, particularly regarding sexual reproduction.Option Analysis
- Their seeds require water for buoyancy. is incorrect. Mosses and ferns are seedless plants. They reproduce via spores, not seeds. Therefore, seed buoyancy is not a relevant factor.
- Their reproduction depends on water for spore germination and fertilisation. is correct. The primary reason these plants require a moist environment is for fertilization. The male gametes (antherozoids) in both mosses and ferns are flagellated and motile. They require a thin film of water to swim from the antheridium (male sex organ) to the archegonium (female sex organ) to fuse with the egg. Without water, fertilization cannot occur, preventing the completion of the life cycle. Additionally, moisture is essential for the germination of spores.
- They rely exclusively on insect pollination which requires high humidity. is incorrect. Pollination is a characteristic of flowering plants (angiosperms) and gymnosperms. Mosses and ferns do not produce pollen or flowers; thus, they do not rely on insect pollination.
- Their root systems are incapable of absorbing groundwater. is incorrect. While mosses lack true roots and possess root-like structures called rhizoids, ferns possess true root systems capable of absorbing soil water. The inability to absorb groundwater is not the primary reason for their restriction to moist habitats; rather, the dependence on external water for fertilization is the limiting factor.