Description: Submerged or attached floating annuals or perennials with long straggling stems; often producing an extensive rhizome system and/or turions.
Leaves alternate, submerged and/or floating, with stipular more or less sheathing bases that may be decayed and inconspicuous on older parts.
Inflorescences mostly emergent, spicate, several–many-flowered. Flowers 3–4 mm diam. Perianth segments 4. Stamens 4. Carpels 2–5.
Nutlets short-beaked, indehiscent, sessile, smooth to ridged or tuberculate, fused to the enclosed, looped seed.
Distribution and occurrence: World: c. 100 species, cosmopolitan. Australia: 11 species (native), all States.
Two species, P. reduncus and P. tepperi have been removed from this treatment. These species do not occur in NSW. K.L.Gibbons, 7 Apr. 2020.
Text by S. W. L. Jacobs & S. Papassotiriou (1993); edited KL Wilson (Sept 2011)
Taxa not yet included in identification key
Potamogeton x jacobsii
| ||Key to the species|| |
|1||Plants with upper leaves floating, petiolate and dissimilar to the submerged foliage||2|
|Plants with all leaves submerged, sessile and similar||3|
|2||Floating leaves usually more than 1 cm wide (2–5 cm), several; common [this includes P. cheesemanii, P. sulcatus and other spp.]||Potamogeton tricarinatus auct. non F.Muell. & A.Benn. ex A.Benn.|
|Floating leaves usually less than 1 cm wide, few; not common|
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|3||Leaves less than 3 mm wide with an obvious ligule and sheath loosely or not enclosing stem||Potamogeton pectinatus|
|Leaves more than 3 mm wide, no obvious sheath, but with a stipule more or less resembling a ligule|
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|4||Leaves linear, 3–6 mm wide, margins entire, flat, apex obtuse; stipules entire, membranous, becoming laciniate||Potamogeton ochreatus|
|Leaves not linear, usually more than 6 mm wide and/or with undulate margins, apex more or less acute to obtuse; stipules present and membranous, not becoming laciniate, or reduced or falling early|
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|5||Leaves stem-clasping at base, ovate, cordate, margins entire||Potamogeton perfoliatus|
|Leaves not obviously stem-clasping, linear-oblong, not cordate, margins minutely toothed|
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