Description: Herb floating at or sometimes below water surface, solitary or thalli connected to form groups of 2–10 (or more) plants. Roots 1 per thallus (occasionally absent).
Thallus symmetric or slightly asymmetric, circular, broad-ovate to elliptic, oblong, obovate, flat to biconvex, green; veins 1–5; dorsal and ventral scale absent. Budding pouch with slit on margin of thallus, rarely dorsal or ventral to margin.
Inflorescence of 1 female and 2 male flowers together in a membranous bract. Anther 2-locular.
Distribution and occurrence: World: 9 species, almost cosmopolitan. Australia: 5 species (4 species native, 1 species naturalized), all States.
Formerly placed in family Lemnaceae.
Text by B.J. Conn, Flora of New South Wales Vol. 4: 37-38 (1993); edited K.L. Wilson (December 2010)
Taxon concept: Australian Plant Census (accessed May 2017)
| | Key to the species | |
| 1 | Thallus floating on water surface, elliptic to rounded or broad-obovate, opaque, with stalk indistinct; root solitary | Lemna disperma |
| Thallus floating below water surface, except when flowering or fruiting, narrow-ovate to narrow-oblong, translucent, narrowed to a distinct stalk; roots absent | Lemna trisulca |
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