Aquatic and Wetland Vascular Plants of the Northern Great Plains
60. Lemnaceae, the Duckweed Family
1. Lemna L. -- Duckweed
5. Lemna obscura (Austin) Daubs
Quite similar to L. minor and differing mainly as follows: Fronds
obovate to oblong-orbicular, 1.5-3(3.5) mm long, slightly asymmetric, often
reddish beneath, obscurely 3-nerved; upper surface flat to slightly convex,
with a prominent papilla at the apex, the lower surface convex.
Uncommon, s and se SD, e and c NE; (e and s U.S. and Mex., also HI).