Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
60. Lemnaceae, the Duckweed Family
1. Lemna L. -- Duckweed
6. Lemna perpusilla Torr.
Fronds obovate to elliptic, 1-3.3 mm long, oblique at the apex and asymmetric
at the base, light green, not reddish, obscurely 3-nerved; upper surface
slightly convex, with a prominent apical papilla and very often with 1 or 2
others along the midnerve; lower surface flat to slightly convex, with
large air spaces in 1 layer. Turions not produced. Root sheath
with lateral wings; root tip sharply pointed. Fruit obliquely attached
in the pouch; seeds whitish, with 35-60 faint ribs, not escaping the
fruit wall when ripening. Rare, barely entering the s part, with 1 collection
from Hall Co., NE; otherwise KS and s; (e N.Amer., from MA to NE, s to FL, TX,
AZ and into Mex.).
This species flowers and fruits more freely than other duckweeds. It probably
occurs in this region only temporarily.
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