Potamogetonaceae - Pondweed family

Aquatic herbaceous perennials with deciduous stems, forming colonies in water, submerged except for the spikes which are exserted at flowering time and, in some species, the leaf laminae, which may be floating or exposed on bare mud. Rhizome well-developed, rarely 0 or plants perennating by specialised turions. Flowers in axillary or terminal spikes, without bracts, bisexual, actinomorphic. Perianth segments 4, stamens 4. Carpels 4 (or fewer), free, 1-locular. Ovary superior. Ovule solitary.

Worldwide: 2 genera and 90 species, cosmopolitan.