Description: Small, submerged or partly emergent aquatic herbs, ephemeral; stem reduced.
Leaves tufted at base, alternate, slender and subterete to ± flattened; sheath absent.
Inflorescence apparently a reduced cyme with several unisexual flowers arranged in an terminal, umbel-like cluster (often interpreted as a head), subtended by 2–several primary bracts. Flowers not separated by secondary bracts. Perianth absent. Male flowers of 1 stamen; anther basifixed, 2-locular. Female flowers with unknown number of carpels, possibly 3 and fused in Trithuria; ovary with 1 loculus; styles 2 or 3 [5–10 in Hydatella]; ovule 1.
Fruit a small, dry capsule, opening by 3 valves [indehiscent in Hydatella]; seed 1; endosperm almost absent.
Distribution and occurrence: World: 2 genera, 8 species, Australia & New Zealand. Australia: 1 genus, 1 species
Angiosperm Phylogeny Website (Family: Hydatellaceae, Order: Nymphaeales)
A family with cryptic characters, now considered to be a basal angiosperm group near Nymphaeaceae and Cabombaceae, and NOT belonging to the monocots. Also now considered to include only one genus, the name of which is Trithuria (Hydatella is a synonym) - see Sokoloff et al. (2008).
Text by B. J. Conn (1993); edited KL Wilson (June 2008)
Taxon concept: Sokoloff et al. (2008), Taxon 57: 179-200.
|One genus in NSW: Trithuria|