→ Pollination by water is quite rare in flowering plants and is limited to about 30 genera, mostly monocotyledons. → On the other hand water is a regular mode of transport for the male gametes among the lower plant groups such as algae, bryophytes and pteridophytes.
→ It is believed, particularly for some bryophytes and pteridophytes, that their distribution is limited because of the need for water for the transport of male gametes and fertilisation.