Description: Aquatic perennials or annuals, often rhizomatous; stems erect, floating or creeping, often producing buds specialized for vegetative reproduction (turions).
Leaves alternate or opposite, simple, submerged and/or floating; if both present then leaves usually dimorphic.
Inflorescence a mostly emergent pedunculate spike 2- or several–many-flowered, the peduncle sometimes becoming spiral in fruit. Flowers actinomorphic, 2-merous, bisexual. Perianth absent or segments 4, sometimes interpreted as a connective outgrowth. Stamens 2 or 4; anthers 2-locular, extrorse, dehiscing by longitudinal slits. Ovary superior, carpels 2–19, free or partly fused, the basal stipe sometimes elongating in fruit.
Fruit a nutlet or drupelet [or rarely a berry].
Distribution and occurrence: World: 3 genera, 100 species, cosmopolitan. Australia: 2 genera, c. 12 species, all States.
Angiosperm Phylogeny Website (Family: Potamogetonaceae, Order: Alismatales)
Text by S. W. L. Jacobs & S. Papassotiriou (1993); edited KL Wilson (June 2010)
Taxa not yet included in identification key
| ||Key to the genera|| |
|1||Inflorescence usually more than 2-flowered; nutlets sessile; carpels 4||Potamogeton|
|Inflorescence always 2-flowered; drupelets with an elongated stipe; carpels 2–19||Ruppia|