Isoetes attenuata C.R.Marsden & Chinnock

Amphibious herb; corm shallowly 3-lobed, to 10 mm wide. Leaves to 20, spirally arranged, erect, 15–23 cm long, 1–1.5 mm diam., flexible, attenuate, acute, bright green; base to 15 mm wide, broadly winged, white; peripheral fibre strands present; major strands 4; stomata present distally; internal hairs absent; trans-lacunar diaphragms visible; ligule triangular, 2–3 mm long; labium small. Sporangia elliptic to round, 4–7 mm long, 3–4 mm wide, opaque, dark brown; velum absent. Microspores densely spiny, pale grey. Megaspores Type I, spherical, 0.4–0.6 mm diam.; proximal faces with large tubercles; distal face with large tubercles and ridges, drying white.

Found in an ephemeral swamp seasonally inundated with 20–40 cm of water; often grows with Isoetes muelleri among sedges and grasses.