Family Potamogetonaceae
Synonyms: Zannichelliaceae APNI*
Description: Aquatic perennial or annual herbs, often rhizomatous. Stems erect, floating or creeping, often producing turions (propagules in the form of buds).
Leaves submerged and/or floating with a distinct midrib, alternate, those subtending inflorescences often subopposite, simple, stem clasping, sessile or petiolate; margins entire or crisped; apex obtuse to acute. Stipules adnate to blade or free.
Inflorescence erect, usually emergent, a pedunculate spike, capitulate to cylindric, with 2–many flowers. Peduncle often bent when fruiting, submerging the fruit. Flowers actinomophic, tetramerous, bisexual. Perianth segments 4, free. Stamens usually 4, epipetalous; filaments adnate to perianth segments; anthers bilocular, extrose, dehiscing by longitudinal slits. Ovary superior; carpels 2–4, free.
Fruit usually interpreted as drupelet, rarely as nutlet or berry. Embryo coiled inside fruit.
Distribution and occurrence: World: 4-5 genera, c. 100 species, cosmopolitan. Australia: 4 genera, c. 18 species, all States.
External links:
Angiosperm Phylogeny Website (Family: Potamogetonaceae, Order: Alismatales)
Wikipedia The description above (from FoA) may need revision to reflect the current taxon concept.
Text by S.W.L. Jacobs, M.A. Brock. Ruppiaceae, in (ed.), Flora of Australia. Australian Biological Resources Study, Department of Climate Change, Energy, the Environment and Water: Canberra. https://profiles.ala.org.au/opus/foa/profile/Ruppiaceae [Date Accessed: 20 March 2025]; page updated by H. Sauquet (Mar 2025)
Taxon concept: APG IV (2016); Jacobs & Brock in Flora of Australia (accessed 2025); Plants of the World Online (2025)
Taxa not yet included in identification key
Stuckenia
| | Key to the genera | |
| 1 | Leaves floating and/or submerged; inflorescences emergent, pollination occurring in the air; flowers bisexual with 4 perianth segments and stamens and 2–5 carpels | Potamogeton |
| All leaves submerged; inflorescences submerged, pollination occurring underwater water, flowers unisexual, with perianth cup-like, reduced to a few small scales or absent, 1–3 stamens and 1–9 carpels | 2 |
| 2 | Basal leaf sheaths or stipules adnate to leaf blade for most of length; perianth of male flowers consisting of 3 very small segments or a small cup at base of anther mass; anther mass sessile or almost so but sometimes appearing stalked owing to elongation of pedicel; female flowers with 3 carpels enclosed by 3 perianth segments | Althenia |
| Basal leaf sheaths or stipules free from leaf blade; perianth of male flowers absent; anther mass on slender filament; female flowers with (1-) 3 (-9) carpels enclosed within cup-like perianth
Back to 1 | Zannichellia |
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