单脉萍 dan mai ping

Lemna minima Philippi; L. minuscula Herter.

Fronds free floating on water surface, 1-8 coherent in one small group, without green stalk at base (but with a thin white stipe connecting fronds), bright green, without reddish color, obovate, 0.8-4 mm, 1-2 × as long as wide, flat to thickish (but not gibbous on lower surface), with or without indistinct papillae on midline of upper surface, margin entire, base rounded; vein 1, not longer than 2/3 of distance between node and apex. Root 0.2-1.5 cm, sheath not winged, apex rounded to pointed. Turions absent. Ovary with 1 ovule; utricular scale with slit on one side. Fruit not winged. Seed with 12-15 distinct ribs. Fl. (very rare) May-Sep. 2n = 36, 40, 42.

Lakesides, spring pools, ponds, ditches; in regions with suboceanic moderately temperate to warm-temperate climate; sea level to 3000 m [data from general distribution]. Not formally documented in China but expected from further investigation [native to America; introduced elsewhere].

Species possibly occurring in China.