Aquatic and Wetland Vascular Plants of the Northern Great Plains
60. Lemnaceae, the Duckweed Family
3. Wolffia Horkel -- Water-meal
1. Wolffia borealis (Engelm.) Landolt
Fronds ellipsoid to oblong when viewed from the upper side, 0.7-1.2 mm
long, shaped somewhat like a deep boat when viewed from the side, with a raised
pointed apex, dark green on the flat upper surface, lighter green in the thick
lower portion, usually brown-punctate when dried. Calm, fresh water; often occurring
with the following species; extreme s SD and NE; (NH to Ont., MN and SD, s to
FL, TX and CO; also WA, OR and the W. Indies). W. punctata Griseb.