Spirodela oligorrhiza (Kurz) Hegelm.
Lemna oligorrhiza Kurz in J. Linn. Soc. (Bot.) 9, 1867, 267.
Type locality: India. Also reported from Australia, Fiji, N. Caledonia, N. America, China.
Platelets to 5 × 3 mm., elliptic-obovate, slightly asymmetric; dorsal surface green, flat to convex; ventral surface convex, ± inflated, us. strong red-purple; nerves obscure. Roots 2–5. Spathe open along one side. Fr. ovoid, 1-seeded. Seed ribbed, reticulate; operculum prominent.
DIST.: N., S., Ch.
Still, fertile waters; in S. known only east of the main divide.
FL. 11–12–(3). FT. 1–3.
Apparently first recorded in N.Z. in 1930 by Lancaster (T.N.Z.I. 60, 563).