Potamogetonaceae

Inflorescence usually more than 2-flowered. Carpels 4. Mature fruit ± sessile Potamogeton

Leaves sessile or nearly so, all alike, submerged, membranous

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Leaves narrow- to broad-ovate or almost orbicular, 1–4 cm long, cordate and stem-clasping, with 5–7 strong longitudinal veins and fainter intermediate veins. Spikes 1–2 cm long; peduncles longer than the leaves. Fruiting carpels scarcely beaked. Nepean River. Fl. spring–summer Potamogeton perfoliatus

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Leaves lanceolate or oblong to linear. Spikes ± interrupted. Flowers few. Fruiting carpels distinctly beaked