Illustrator: John Myers

Copyright: Flora of North America Association

Fronds nearly globular, 0.5–1.4 mm (x 0.4–1.2 mm), 1–1.3 times as long as wide, 1–1.3 times as deep as wide, rounded at apex, papilla absent; upper surface transparently green, with 1–10(–30) stomates; pigment cells absent in vegetative tissue. 2n = 30 (H, U), 40 (U), 42 (D), 500 (U), 70 (70), 80 (U).

Phenology: Flowering (very rare) summer–early fall.
Habitat: Mesotrophic to eutrophic, quiet waters in temperate to subtropical regions
Elevation: 0–1100 m

Distribution

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Alta., Man., Ont., Que., Sask., Ala., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., S.C., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis., Mexico, West Indies (Cura�ao), Central America, South America.

Discussion

I know of no specimens of Wolffia columbiana from Rhode Island.

Selected References

Brooks, J. S. 1940. The Cytology and Morphology of the Lemnaceae. Ph.D. thesis. Cornell University.

Dore, W. G. 1957. Wolffia in Canada. Can. Field-Naturalist 71: 10--16.

Landolt, E. and Urbanska-Worytkiewicz K. 1980. List of the studied Lemnaceae samples: origin and chromosome numbers. Veröff. Geobot. Inst. Rübel Zürich 70: 205--247.

Lower Taxa

None.