Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
60. Lemnaceae, the Duckweed Family
1. Lemna L. -- Duckweed
2. Lemna gibba L.
Fronds orbicular to obovate, 2-5(6) mm long, symmetric or not, green
to yellowish-green, often red-tinged or mottled on both surfaces, 3- to 5-nerved,
when 4- to 5-nerved the lateral and inner nerves diverging from the same point
at the node; upper surface flat to slightly convex, with a prominent
central papilla and usually a row of smaller papillae extending to near the
apex, lacking a prominent papilla at the apex (except for small fronds); lower
surface convex to very often much inflated (gibbous), with air spaces in
2 layers, those of the bottom layer often more than 0.3 mm in diameter. Turions
not produced, or if turionlike fronds are present, then these have short roots
and are slowly growing daughter fronds. Root sheath not winged, root
tip mostly rounded. Fruit ovoid to ellipsoid, with lateral wings 0.1-0.2
mm wide; seeds (1)2-6, ovoid to ellipsoid. Rare, w NE; (In mild climates
over most of the world except S.Amer. and Australia).
Although this species and the following are distinct in fruiting condition,
they are often difficult to tell apart vegetatively. This is especially true
when dealing with the occasional uninflated forms of L. gibba.
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Return to Family -- Lemnaceae - The
Next Section -- Lemna minor L.