Lemna

Scientific name

Lemna L.

Common names

duckweed

Family

Lemnaceae

Similar genera

Spirodela, Wolffia, Wolffiella

Native distribution

cosmopolitancosmopolitan:
(adj) essentially worldwide in distribution

Species cultivated

Lemna aequinoctialis Welw.

L. gibba L.

L. minor L.

L. trisulca L.

Adventive distribution

Lemna minor is introduced into Japan, Australia, and New Zealand, while L. minuta Kunth ex. Humb. is introduced into Asia and Europe.

Weed status

a weed of rice fields

Habit

free-floating, minute, thallusthallus:
(n) a photosynthetic plant body that is not (or apparently not) differentiated into stems, roots, and leaves
-like plant

Brief description

Free-floating on or (rarely) below water surface. Reduced plant body, undifferentiated into stem and leaf. Frondfrond:
(n) (1) a term used to describe the leaves of, e.g., ferns, palms, or duckweeds; (2) a leaf-like organ (as in .e.g. some algae, such as Caulerpa)
broadly ovateovate:
(adj) egg-shaped in outline; generally with the broad end at or near the base
to oblongoblong:
(adj) two to four times longer than wide, with +/- parallel sides
, not lobedlobed:
(adj) divided into (usually rounded) segments
or divided (except L. trisulca), sometimes with a narrow petiolepetiole:
(n) the stalk of a leaf
-like base (e.g., L. trisulca); venationvenation:
(n) the arrangement of veins in a leaf
palmatepalmate:
(adj) (of leaves or venation) with lobes, leaflets, divisions or veins originating from the same point
; marginmargin:
(n) edge; rim
entire or with slight serrations on apicalapical:
(adj) of the apex
marginmargin:
(n) edge; rim
; daughter fronds borne in two ventralventral:
(adj) of the front of an organ or the side facing or nearest the axis (syn. adaxial) (compare dorsal); upper surface
budding pouches. Roots solitary, unbranched, arising from center of each frondfrond:
(n) (1) a term used to describe the leaves of, e.g., ferns, palms, or duckweeds; (2) a leaf-like organ (as in .e.g. some algae, such as Caulerpa)
or (rarely) absent. Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
rare, minute, of 1 female and 2 male flowers enclosed in a membranous spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
, borne in budding pouch. Dispersal by frondfrond:
(n) (1) a term used to describe the leaves of, e.g., ferns, palms, or duckweeds; (2) a leaf-like organ (as in .e.g. some algae, such as Caulerpa)
budding and seeds.

Natural habitat

still waters of lakes, rivers, and swamps

Additional comments

A cosmopolitancosmopolitan:
(adj) essentially worldwide in distribution
genus containing 14 species. Three species are commonly cultivated, although usually inadvertently, in aquaria and ponds. The monotypicmonotypic:
(adj) represented by a single example (species)
genus Landoltia is morphologically not very different from Lemna, and may not warrant separation of Landoltia punctata (G.F.W. Meyer) Les & Crawford into its own genus. Molecular data (Les and Crawford 1999) suggest that Landoltia is indeed justified. A short dichotomous key to Lemnaceae is presented below.