Potamogeton australiensis
A.Benn. Thin PondweedEmergent herb, with branches flattened, up to c. 2.7 m long. Leaf sheath free, up to 4 cm long, soon torn; ligule absent. Leaves usually thin and translucent, submerged leaves different from emergent ones. Submerged leaves sessile or very shortly petiolate; lamina narrowly ovate or narrowly elliptic to broadly ovate, 5–23 cm long, 0.5–9 cm wide; base rounded to often tapered; margin flat or often finely undulate; apex obtuse to subacute; 5–22 principal longitudinal veins, with finer, transverse secondary veins; distal submerged leaves more like emergent leaves, but often with petiole much longer than for emergent leaves. Emergent leaves floating, petiolate; lamina ovate or broadly elliptic to subcircular, 1.5–9.5 cm long, 0.9–6.5 cm wide, shining and often glossy; margin often finely undulate; 11–35 principal longitudinal veins, with prominent transverse secondary veins. Inflorescence c. 12–20-flowered. Infructescence 1.5–4.5 cm long. Fruiting carpels 2–2.5 mm long (including distal point), dorsally with a low smooth keel and 2 low lateral ridges, distally with a ± straight point less than 0.5 mm long. Flowers and fruits Dec.–Feb.
LoM, Wim, GleP, Brid, VVP, VRiv, RobP, MuF, GipP, OtP, WaP, GGr, DunT, EGL, EGU, WPro, HSF, MonT. Also SA, NSW, Tas. Occurs in still or slowing flowing fresh water, in heathland swamps and creeks, on muddy substrate.
Conn, B.J. (1994). Potamogetonaceae (including Ruppiaceae). In: Walsh, N.G.; Entwisle, T.J., Flora of Victoria Vol. 2, Ferns and Allied Plants, Conifers and Monocotyledons, pp. 147–155. Inkata Press, Melbourne.
