Isoetes gunnii A.Braun

Aquatic herb; corm 3-lobed, 3–4 cm wide. Leaves to 60, spirally arranged, erect or recurved, 3 –18 cm long, 2–5 mm diam., thick, rigid, tapering to apex, acute or obtuse, dark green; base to 16 mm wide, broadly winged, white but often brownish on margins; peripheral fibre strands absent, but mesophyll cells thickened; stomata and internal hairs absent; trans-lacunar diaphragms not visible; ligule broadly triangular, c. 1 mm long with a cordate base; labium absent. Sporangia round to obovate, to 6 mm long, 8 mm wide, dark brown, opaque; velum absent. Microspores granulose, dark brown. Megaspores Type I, large, 0.6–0.9 mm diam.; proximal and distal faces smooth or mostly tuberculate, drying white or grey.

Occurs in subalpine lakes in which it often forms dense carpets.