Trithuria australis (Diels) D.D.Sokoloff, Remizowa, T.D.Macfarl. & Rudall

Tufted, monoecious aquatic annual. Leaves few, lax, filiform, terete, to 2.5 cm long. Capitula on scapes 3-5 mm long; male capitula fewer than female; bracts 2, rarely 4, lanceolate-acuminate, loosely sheathing, 2-4 mm long. Male flowers 4-8 per capitulum; stamens exserted sequentially; anther oblong, 0.6-1 mm long, pale purple; filament 5-8 mm long. Female flowers 8-14 per capitulum, loosely grouped; pedicel to 1 mm long; ovary ovoid, c. 0.3 mm long; stigmatic hairs 4-10, unequal, to 0.8 mm long. Fruit ovoid, wrinkled, with 2 or 3 obscure veins, c. 0.4 mm long, pale brown.

Grows submerged in shallow pools and seasonal swamps.