Bryophytes

Mosses and liverworts, treated as bryophytes in NCERT Class 11, Chapter 3 (Plant Kingdom), can live in soil but depend on water for sexual reproduction, which is exactly why they are called the amphibians of the plant kingdom. The male sex organ, the antheridium, produces flagellated antherozoids that must swim through a film of water to reach the female archegonium, where fertilisation occurs. Hence the dependence on water for the movement of motile male gametes is the correct reason. The idea that they need soil moisture merely for photosynthesis is incorrect, since all plants require water for photosynthesis and this is not what the phrase refers to. Dependence on insects for spore transfer is wrong because bryophyte spores are dispersed by wind, not insects, and there is no pollination in this group. The necessity of submersion for seed germination is invalid because bryophytes are non-seed plants that reproduce by spores. A consistency check supports the answer: an organism needing external water specifically to complete fertilisation mirrors amphibian biology, justifying the analogy and confirming gamete transport as the key dependency.