Taxon	Illustrator ⠉
	Lemna minor Spirodela punctata Lemna trisulca Wolffia borealis Lemna obscura Wolffia arrhiza Wolffia columbiana Lemna minuta Lemna perpusilla Wolffiella gladiata Spirodela polyrrhiza Lemna turionifera Lemna valdiviana Wolffiella lingulata Lemna gibba Wolffia brasiliensis Lemna aequinoctialis Wolffiella oblonga Wolffia globosa	John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers John Myers

Roots absent. Fronds submersed (except when flowering or fruiting), proximal part near surface, 1 or 2–20 or more, coherent, linear, ribbon, sabre or tongue-shaped, or ovate, flat, longer than 2 mm, margins entire; air spaces in tissue; pouch 1, terminal, at base from which daughter fronds (no flowers) originate, triangular, lower wall of pouch with tract of elongated cells forming connection between node and attachment to mother frond; veins 0; scale at base of frond absent; anthocyanins absent; pigment cells present (visible in dead fronds as brown dots); turions absent. Flowers 1 (–2) per frond, originating in cavity at side of median line of upper frond surface, not surrounded by utricular scale; stamen 1, 2-locular. Seeds 1, nearly smooth. x = 10, 20, 21.

Distribution

North America, West Indies, Central America, South America, Africa

Discussion

Species 10 (3 in the flora).

Selected References

None.

Lower Taxa

Wolffiella gladiata, Wolffiella lingulata, Wolffiella oblonga

Key

1	Fronds (4–)6–15(–20) times as long as wide; angle of pouch 25°–50°.	Wolffiella gladiata
1	Fronds 1.5–8 times as long as wide; angle of pouch 45°–120°.	> 2
2	Angle of pouch 70°–120°; tract of elongated cells running between median line and edge of lower wall of pouch; area of air spaces within frond rarely longer than wide.	Wolffiella lingulata
2	Angle of pouch 45°–90°; tract of elongated cells running along or close to edge of lower wall of pouch; area of air spaces within frond mostly longer than wide.	Wolffiella oblonga