Hydroplzytes and hemi-hydrophytes (aquatic plants).Of marine hydrophytes, there are, in this country, only the grass-wracks (Zostera marina and Z.
Very few aquatic plants are pollinated under water, but this is wellknown to occur in species of Zostera and of Naias.
Harbours and shallows covered with Zostera are likewise favourite haunts of this species, although the water may be brackish.
Porphyra laciniata, the edible laver; Codium tomentosum, a coarse species; Padina pavonia, common in shallow water; Ulva latissima; Haliseris polypodioides; Sargassum bacciferum; the well-known gulf weed, probably transported from the Atlantic; Zostera marina, forming dense beds in muddy bays; the roots are cast up by storms and are valuable to dress the fields.
In these the pollen floats on the surface and reaches the stigmas of the female flowers as in Callitriche, Ruppia, Zostera, Elodea.