Lemna minor L.

FRONDS 1-8 (very rarely up to 10) mm long, 0.6-5.0 (very rarely up to 7.0) mm wide, 1 1/3-2 times as long as wide; shiny on the upper surface; with some indistinct papules along the median line (papules near the tip and above the node somewhat larger than the ones between), with 3 (rarely up to 4-5) nerves; if 4-5 nerves present the outer lateral nerves originate from the lower part of the inner lateral nerves,; never gibbous (not thicker than about 1 mm), on the upper surface occasionally diffusely reddish (especially during the cold season), on the lower surface very rarely slightly reddish (but much less intensely than on the upper surface); greatest distance between the inner lateral nerves in or somewhat below the middle of the nerves; largest air spaces rarely wider than 0.3 mm; rootcap usually rounded (living and dried material) ; no rootless turions which sink to the bottom of the water present. INFLORESCENCE: Plants occasionally flowering and very rarely fruiting. Ovary with 1 ovule; style 0.10-0.15 mm long INFRUCTESCENCE: fruit 0.8-1.0 mm long, 0.8-1.1 mm wide, with winged margin; wing 0.05-0.10 mm wide; seed 0.7-1.0 mm long, 0.4-0.6 mm thick, whitish, with 10-16 distinct ribs, stays within the fruit wall after ripening.