Aquatic and Wetland Vascular Plants of the Northern Great Plains
60. Lemnaceae, the Duckweed Family
1. Lemna L. -- Duckweed2. 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.
Previous Section -- Lemna aequinoctialis Welw.
Return to Family -- Lemnaceae - The Duckweed Family
Next Section -- Lemna minor L.
