On the occurrence of Wolffia arrhiza, Wimm.,in Tasmania.

Marsh plants have generally the widest distribution, and of the Duckweeds these are no exceptions. Lemna minor, L., and Lemna trisulca, L., both cosmopolitan species, are the only plants of this family that have hitherto been recorded from Tasmania. We now may report Wolffia.
Growing in a marsh near Lewisham, also on Maria Island.
The genus Wolffia is of quite a different structure.
Instead of floating horizontally, it does so perpendicularly, exposing an edge to the air and sinking the greater portion of the frond as an oblique plate. Flowering is unisexual, and takes place in the centre of the exposed portion. It bears no root. The following notes are a description of Wolffia arrhiza as found in Tasmania.