Trithuria cookeana is a species of aquatic plant in the family Hydatellaceae endemic to the Northern Territory, Australia.

[1] Trithuria cookeana is an annual aquatic herb with linear leaves.

Male individuals have 10 reproductive units, which are produced on 13–30 mm long peduncles.

Female individuals produce up to 45 reproductive units on 12–40 mm long peduncles.

[2][1] The type specimen was collected by Ian D. Cowie 24 km Southeast of Maningrida, Northern Territory, Australia on the 22nd of August 1995.