Wolffia arrhiza
Lemna arrhiza L. Mantissa 1771, 294.
Water-meal.
Type locality: Italy.
Platelets ellipsoidal, dorsal surface weakly convex, the central green part merging into a colourless rounded shoulder; submerged portion much larger than that above water, pale, loosely cellular, ± semi-circular in side view but laterally compressed.
DIST.: N., S.
Widespread in the Old World but other spp. take its place in the Western Hemisphere.
Still, fertile waters; in S. known only east of the main divide.
FL. 11–12–(2).
First recorded in N.Z. in 1950 by Mason who remarks: "In winter it becomes swollen with stored starch grains and sinks to the bottom, rising again later in the year."
