Trithuria

Trithuria is a genus of minute aquatic herbs in the family Hydatellaceae. Recently the genus Hydatella was subsumed within Trithuria.

These diminutive, moss-like, aquatic plants are the closest living relatives of water-lilies and their allies. They reside near the point at which water-lilies (order Nymphaeales) diverged from other flowering plants. Together, the Nymphaeales+Hydatellaceae are sister to all other extant flowering plants except Amborella trichopoda.^[1]

Morphology places these plants near the base of the angiosperm clade. This position is supported by ten synapomorphies:

• lack of a vascular cambium,
• lack of pericyclic sclerenchyma,
• anomocytic stomata,
• truncate anther connective,
• boat-shaped pollen,
• inner integument with two cell layers,
• palisade exotesta,
• seed operculum formed by cell enlargement in the inner integument,
• perisperm and
• hypogeal germination.^[2]

References