3. Lemna minuta Kunth (least duckweed)
Pl.
97 e–g; Map 384
L. minima Phil. ex Hegelm.
L. miniuscula Herter
Plants of single fronds or with 2 or 3 fronds connected by small stalks that
soon wither, not producing turions. Roots 0.5–1.5 cm long, the sheath at the
base not winged, the tip somewhat pointed or more commonly blunt in fresh
material. Fronds 1.0–3.0(–4.0) mm long, lacking reddish pigment, flattened,
usually symmetrically ovate, the bases rounded, the margins entire. Papules
absent or indistinct. Vein 1 per frond, usually indistinct and difficult to
see, extending less than 2/3 of the distance from the attachment point of the
roots to the tip. Fruits 0.6–1.0 mm long, the seed with 12–15 ribs. 2n=36,
42.
Uncommon in the eastern half of Missouri (U.S. south to southern South America;
West Indies). Floating on shallow, stagnant water of ponds, lakes, sloughs,
ditches, and swamps, often forming mats; also in still backwaters and margins
of spring branches, streams, and rivers, sometimes stranded on mud by receding
waterline.
Reveal (1990) has discussed the confusing nomenclatural history of this taxon.