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FNA | Family List | FNA Vol. 22 | Lemnaceae

1. Spirodela Schleiden, Linnaea. 13: 391. 1839.

Duck-meal [Greek speira, winding, and delos, distinct]

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.

Species 3 (2 in the flora): nearly worldwide.

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

Lower Taxa


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