Lemna obscura |
Lemna minuta |
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little duckweed |
least duckweed |
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Roots | to 15 cm, tip mostly rounded; sheath not winged. |
to 1.5 cm, tip rounded to pointed; sheath not winged. |
Flowers | ovaries 1-ovulate, utricular scale with narrow opening at apex. |
ovaries 1-ovulate, utricular scale open on 1 side. |
Fruits | 0.5–0.7 mm, not winged. |
0.6–1 mm, not winged. |
Seeds | with 10–16 distinct ribs, staying within fruit wall after ripening. |
with 12–15 distinct ribs. |
Stipes | white, small, often decaying. |
white, small, often decaying. |
Fronds | floating, 1 or 2–5 or more, coherent in groups, obovate, flat or gibbous, 1–3.5 mm, 1–1.5 times as long as wide, margins entire; veins 3, greatest distance between lateral veins near middle; very distinct papillae near apex, some smaller indistinct ones on midline of upper surface; lower surface very often red colored (more intensely than on upper), coloring beginning at attachment point of root, lower upper surface sometimes with red spots; air spaces shorter than 0.3 mm; distinct turions absent. |
floating, 1 or 2–few, coherent in groups, obovate, flat to thickish (but not gibbous), 0.8–4 mm, 1–2 times as long as wide, margins entire; veins 1, sometimes indistinct, very rarely longer than extension of air spaces, not longer than 2/3 of distance between node and apex; with or without small papillae along midline; anthocyanin absent; largest air spaces much shorter than 0.3 mm; turions absent. |
2n | = 40, 42, 50. |
= 36 (U), 40 (U), 42 (G). |
Lemna obscura |
Lemna minuta |
|
Phenology | Flowering (occasional) spring–fall. | Flowering (very rare) late spring–early fall. |
Habitat | Mesotrophic to –eutrophic, quiet waters, in temperate to subtropical regions with mild winters | Mesotrophic to eutrophic, quiet waters in temperate to subtropical regions with relatively mild winters |
Elevation | 0–800 m (0–2600 ft) | 0–2600 m (0–8500 ft) |
Distribution |
AL; AR; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MD; MN; MO; MS; NC; NE; NJ; NY; OH; OK; PA; SC; SD; TN; TX; VA; WI; c Mexico; South America (Colombia, Ecuador); Hawaii
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AL; AR; AZ; CA; CO; FL; GA; IL; IN; KS; KY; LA; MI; MO; NE; NM; NV; OH; OK; OR; TN; TX; UT; WA; WV; WY; Mexico; Central America; South America; West Indies [Introduced, Eurasia (introduced)]
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Discussion | I know of no specimens of Lemna minuta from Mississippi, but the species is to be expected there. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 22. | FNA vol. 22, p. 150. |
Parent taxa | Lemnaceae > Lemna | Lemnaceae > Lemna |
Sibling taxa | ||
Synonyms | L. minor var. obscura | L. minima, L. minuscula |
Name authority | (Austin) Daubs: Illinois Biological Monographs 34: 20. (1965) | Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 1: 372. (1816) |
Web links |
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