Wolffia borealis
Ber. Geobot. Inst. ETH Stiftung Rubel 44:137. 1977.
Common names: Wolffie boréale
WeedyIllustratedEndemic
Basionym: Wolffia brasiliensis var. borealis Engelmann in C. F. Hegelmaier, Lemnac., 127. 1868
Treatment appears in FNA Volume 22. Treatment on page 152.
Fronds boat-shaped, 0.7–1.5 mm, 1.3–2 times as long as wide, 0.7–1 times as deep as wide, with point at apex bent upward; papilla absent; upper surface intensely green, with 50–100 stomates; pigment cells present in vegetative tissue (visible in dead fronds as brown dots). 2n = 20, 22, 30, 40.
Phenology: Flowering (very rare) summer–early fall.
Habitat: Mesotrophic to eutrophic, quiet waters in temperate regions
Elevation: 0–1400 m
Distribution
Alta., B.C., Ont., Que., Calif., Colo., Idaho, Ill., Ind., Iowa, Kans., Ky., Mass., Mich., Minn., Mo., Mont., Nebr., N.H., N.Y., Ohio, Okla., Oreg., Pa., S.Dak., Tenn., Utah, Vt., Wash., Wis.
Discussion
The name Wolffia punctata has been applied to this species in error.
I know of no specimens of Wolffia borealis from Rhode Island.
Selected References
None.
Lower Taxa
None.