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Duckweed - Lemna minor
Family: Lemnaceae

TPIUC

Description

The Lemnaceae are the structurally simplest of the flowering plants. The plants are not differentiated into stems and leaves; instead, the plants in the family have an undifferentiated leaf-like body commonly referred to as a frond or thallus. The most recent treatment of the family by Landolt (1986) recognizes 34 species in the genera Spirodela, Lemna, Wolffiella, and Wolffia. Other treatments of the family include those of Hartog and Van der Plas (1970) and Daubs (1965).

The various genera in the Lemnaceae can be distinguished by the following characteristics:

Plants usually with 2 to several roots on the lower side of the fronds; under surface of the frond usually reddish; nerves 3 to 15 and usually distinct

Spirodela

Plants with 1 root on the lower surface side of the fronds (except L. trisulca which is often rootless); the under surface of the frond green or streaked with brown; nerves 1 to 3, often indistinct

Lemna

Plants rootless; fronds thick, globoid to ovoid, boat- or nutshell-like, barely discernible to the naked eye

Wolffia

Plants rootless; fronds thin, essentially flat, ovate to linear, often asymmetrically curved, easily visible

Wolffiella

According to the treatment of Landolt (1986), nine species of Lemna occur in the United States. With the exception of L. trisulca L., which is attached to the parent plant by a narrow stipe, identification of the various species of Lemna is often difficult. The treatment of Landolt (1986) also includes some names of species that are not in usage in regional floras that predate Landolt’s monographic study. For these reasons, this system does not attempt to separate the various species of Lemna, except for L. trisulca which is readily distinguishable from the other species of Lemna. The user of this system should consult a regional flora manual to distinguish the various species of Lemna.

Interesting facts

The common name comes from its size relative to that of the other common North American duckweed, Greater Duckweed (Spirodela polyrhiza).

VIDEO

Links to more information

US Army Corp of Engineers

Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers