Hygrochloa, a new genus of Aquatic grasses from the Northern Territory.

A new genus of two species of grasses (Hygrochloa aquatica, H. cravenii), with distinctive aquatic and unisexual features, is described and illustrated. Diagnostic characters include staminate and pistillate, dimorphic spikelets in different parts of the same inflorescence, papillose leaf blades, hollow culms with air canals in the culm walls, and prolonged apices of the rhachides and axes. The genus, though most closely allied to Paspalidium Stapf, is of remote affinity in the Tribe Paniceae.