bio

Gametophyte

The haploid plant body — it carries a single chromosome set, and it makes eggs and sperm by mitosis rather than meiosis. In a moss, the gametophyte is the green mat you see. In a fern it is a small free-living sheet on damp ground, and because its sperm must swim, it ties ferns to water. In a seed plant it has shrunk to a few cells inside pollen and ovule — and that reduction is exactly what decoupled fertilisation from standing water and opened the way to the seed.