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


Common Duckweed

Sp. Pl. 1: 970; 1753.


Roots: One root.

Shape of Plant Body: Flattened, suborbicular to elliptic-obovate in outline, generally symmetrical; dorsal surface smooth (without prominent papules or median ridge).

Size: 2-4 mm long.

Veins: 3 veins.

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

Flower (Fruit) Position: Within membranous, saclike spathe (open at top only) inside budding pouches.

Arrangement of Clonal Clusters: Solitary or several (3-5) attached.

Habitat: Fresh water ponds, marshes, lakes and quiet streams.

Range: Throughout Pacific states from sea level to 2,000 m; widespread in northern hemisphere, including North America, Europe, Russia and Asia; also in southern hemisphere, including Australia and New Zealand.

Other Information:

The lack of overwintering turions, lack of dorsal papules, and lack of reddish anthocyanin blotches on ventral side separate this sp. from the closely related L. turionifera Landolt; the symmetrical apex, lack of anthocyanin mottling on dorsal surface and lack of dorsal median ridge separate it from nongibbous forms of L. gibba L.; also the one-seeded fruits (utricles) lack the lateral wings of L. gibba fruits; a similar "obscure" species L. obscura (Austin) Daubs, with prominent apical papule and reddish anthocyanin grows in the southeastern United States. The latter species appears fairly distinctive, but so far has not been reported in the western continental United States. According to Landolt (1986) it has been introduced into the Hawaiian Islands (Oahu). It is readily identified by its smooth dorsal surface (similar to L. minor) and pronounced apical papule. The only other species in the western United States with a single prominent apical papule is L. aequinoctialis, but it also has a nodal papule (above root) and a basal root sheath with 2 lateral winglike appendages.

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