Lemna gibba L.

FROND 1-8 mm long, 0.8-6 mm wide, 1-1 1/2 times as long as wide; somewhat shiny on the upper surface, usually without distinct papules (sometime smaller fronds with well visible papules near the tip) , usually with 4-5 nerves (rarely up to 7 nerves; small fronds sometimes only with 3 nerves); the lateral nerves originate independently from the node; very often gibbous (up to 4 mm thick); on the upper surface occasionally with distinct red spots, especially near the tip; on the lower surface sometimes red coloured, especially near the margins, on the nerves or on the cells between the air spaces, the pigmentation rarely beginning from the node; greatest distance between the inner lateral nerves in or somewhat above the middle of the nerves; largest air spaces wider than 0.3 mm; rootcap mostly rounded (living material) or often pointed (dried material), 0.6-1.8 mm long (the other species of the group up to 1.2 mm long); no rootless turions which sink to the bottom of the water present. INFLORESCENCE: Plants often flowering and fruiting. Ovary with 1-7 ovules; style 0.05-0.1 mm long INFRUCTESCENCE: fruit 0.6-1.0 mm long, 0.8-1.2 mm wide, with winged margin; wing 0.1-0.2 mm wide; seeds 1-5 per fruit, 0.7-0.9 mm long, 0.4-0.6 mm thick, whitish, with 8-16 distinct ribs, fall out of the fruit wall after ripening.