Wayne Armstrong's On-line Description of Lemna trisulca (Lemnaceae)
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Lemna trisulca

Linnaeus

Ivy-Leaved Duckweed

Sp. Pl. 1: 970; 1753

Description:

Roots: Often rootless or with a single root.

Shape of Plant Body: Submersed vegetative plant body flattened, oblong-lanceolate to elliptic, tapering at base into a long, slender stipe (stalk); flowering plant body shorter and thicker, with serrate margin and shorter stipe, floating at water surface like most other duckweed spp.

Size: 6-10 mm long (excluding stipe).

Veins: 3 veins (middle vein more prominent).

Budding Pouch Position: 2 lateral pouches on either side of basal end.

Flower (Fruit) Position: Within membranous cuplike spathe (open on one side) inside the budding pouches.

Arrangement of Clonal Clusters: Connected in branched chains of 8-30 (or more) plants by long, attenuate stipes; forming tangled masses under the water surface.

Habitat: Cool, freshwater creeks, ponds and marshes; often extending into mountain meadows of higher elevations.

Range: Throughout Cascade Ranges, Sierra Nevada, Great Basin, and coastal ranges and valleys of the Pacific Northwest; extending north to Alaska and east to the Atlantic Coast, Europe, Africa, Asia and Australia.

Other Information:

Vegetative plants with long stipes connected in chains are morphologically distinct from all other North American Lemna spp.; smaller flowering plants can readily be separated from other spp. by their serrated margin; not known to produce overwintering turions, probably survives severe winters submersed beneath the frozen water surface.

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