Wolffia

Scientific name

Wolffia Horkel ex Schleid.

Common names

duck weed, water meal

Family

Araceae

Similar genera

Lemna, Wolffiella

Native distribution

almost cosmopolitan

Species cultivated

Wolffia angusta Landolt

W. arrhiza (L.) Horkel ex Wimm.

W. globosa (Roxb.) Hartog & Plas

W. welwitschii Hegelm. [synonym of Wolffiella welwitschii (Hegelm.) Monod]

Adventive distribution

Wolffia globosa is introduced into North America.

Weed status

often a minor weed in eutrophic waters and rice fields

Habit

free-floating, very minute, thallus-like plant

Brief description

Minute (rarely exceeding 1 mm), free-floating on or just below water surface. Reduced plant body, undifferentiated into stem and leaf. Roots absent. Fronds broadly ovateovate:
(adj) egg-shaped in outline; generally with the broad end at or near the base
, spherical to oblongoblong:
(adj) two to four times longer than wide, with +/- parallel sides
, venationvenation:
(n) the arrangement of veins in a leaf
absent; marginmargin:
(n) edge; rim
entireentire:
(adj) having a continuous margin that is not toothed or lobed
. Daughter fronds borne in a funnel-shaped basalbasal:
(adj) at or pertaining to the base, or point of attachment
budding pouch with a circular opening. Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
rarely occurring, minute, of 1 female and 1 male flower. Flowers produced in budding pouch in middle of 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 <em>Caulerpa</em>)
. Membranous spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
lacking. 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 <em>Caulerpa</em>)
budding and seeds.

Natural habitat

still waters of lakes, rivers, and swamps

Additional comments

Wolffia globosa is the world's smallest flowering plant (size: 0.5 mm x 0.3 mm). Wolffia is a cosmopolitancosmopolitan:
(adj) essentially worldwide in distribution
genus containing 11 species. Three species are commonly cultivated, although usually inadvertently, in aquaria and ponds.