Lemna valdiviana
Linnaea 33:239. 1864.
Roots to 1.5 cm, tip rounded to pointed; sheath not winged. Stipes white, small, often decaying. Fronds floating or (rarely) submersed, 1 or 2–few, coherent in groups, ovate to lanceolate, flat, thin, 1–5 mm, 1.3–3 times as long as wide, margins entire; veins 1, mostly prominent, longer than extension of air spaces, or running through at least 3/4 of distance between node and apex; with or without small papillae along midline of upper surface; anthocyanin absent; largest air spaces much shorter than 0.3 mm; turions absent. Flowers: ovaries 1-ovulate, utricular scale open on 1 side. Fruits 1–1.35 mm, not winged. Seeds with 15–29 distinct ribs. 2n = 40, 42.
Phenology: Flowering (very rare) spring–fall.
Habitat: Mesotrophic, quiet waters in temperate to tropical regions
Elevation: 0–2000 m
Distribution
Ala., Ariz., Ark., Calif., Conn., D.C., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Mass., Mich., Miss., Mo., Mont., Nebr., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Va., W.Va., Wyo., Mexico, West Indies (Bermuda), Central America, South America.
Discussion
I know of no specimens of Lemna valdiviana from Delaware, but the species is to be expected there.
Selected References
None.