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 (1–) 2–21 per frond, abaxial surface at node. Fronds floating (only turions sink to bottom), 2–10, coherent in groups, each obovate-circular, flat or gibbous, 1.5–10 mm, margins entire; air spaces in tissue; reproductive pouches 2, lateral, at base from which daughter fronds and flowers originate, triangular; veins (3–) 5–16 (–21), from point in proximal part of frond (node); small bifid 2-cleft membranous scale (interpreted as prophyllum) enveloping base of frond, covering point of attachment of roots; anthocyanins present (especially on abaxial surface); pigment cells present (visible in dead fronds as brown dots); turions present or absent, brownish olive, circular-reniform, smaller than growing frond. Flowers 1 (–2) per frond, surrounded by small utricular, membranous scale; stamens 2, 4-locular. Seeds 1–3, longitudinally ribbed. x = 10, 18, 23.

Distribution

Nearly worldwide

Discussion

Species 3 (2 in the flora).

Selected References

None.

Lower Taxa

Spirodela polyrrhiza, Spirodela punctata

Key

1	Fronds 1–1.5 times as long as wide, with 7–16(–21) veins and 7–21 roots, 1 or 2 perforating scale	Spirodela polyrrhiza
1	Fronds 1.5–2 times, as long as wide, with (3–)5–7 veins and (1–)2–7(–12) roots, all perforating scale.	Spirodela punctata