Synonyms: Hydatella submersa; Juncella invalidum; Juncella tasmanica.
Name: Trithuria is derived from the Greek words treis, three, and thyris meaning window.
Clades: Hydatellaceae.
Genus: 14 species.
Region: India, Australia, New Zealand.
Habitat: aquatic.

BotanyType: herb; small ephemeral; aquatic; diminutive; simple; moss-like.
Root: rooted in the substrate below the water.
Leaves: simple; basally around a short stem.
Flowers: cosexual, hermaphroditic or dioecious; reduced to small collections of minute stamen- and or pistil-like structures,pseudanthia; may represent condensed inflorescences or non-flowers.
Pollination: by wind, anemophilous, or self-pollinating, autogamous).
Fruits: non-fleshy; follicles or achenes: typical is allocating nutrients to the embryo before fertilization, similar to gymnosperms; dehiscence in 3 windows.
Chromosome count: 2n = c, 24; diploid 2n = 56.

TaxonomyTrithuria was initially placed in the family Restionaceae, in the order Poales. Trithuria has superficial resemblance to Liliidae and is very similarity to Centrolepis, each mistaken for the other genus. It has similiraty with Lacandonia schizmatica and braziliana of Triuridaceae, in which the stamens are centred and surrounded by the pistils.
Later it was separated as its own family Hydatellaceae.
In 2007 it was identified as a basal angiosperm lineage and got placed by the APG III system in the order Nymphaeales, or in a separate order Hydatellales, due to proof from DNA and morphology.