Trithuria fitzgeraldii is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.

The more numerous female reproductive units, which surround the male ones, has two bracts, and bears carpels with up to 2 mm long stigmatic papillae.

[1] It was described by Dmitry Dmitrievich Sokoloff, Isabel Marques, Terry Desmond Macfarlane, Paula J. Rudall, and Sean W. Graham in 2019.

[2][1] The type specimen was collected by N. Gibson about 4 km North of Waroona in the Australian state of Western Australia on the 5th of November 2004.

[2] It occurs in ephemeral, freshwater to slightly saline pools at the edge of lakes or swamps.