Wolffia arrhiza

(Linnaeus) Horkel ex Wimmer
Fl. Schles., ed. 3 140. 1857.
WeedyIntroducedIllustrated
Basionym: Lemna arrhiza Linnaeus Mant. Pl. 2: 294. 1771
Treatment appears in FNA Volume 22. Treatment on page 152.

Fronds globular to ovoid, 0.5–1.5 mm, 1–1.3 times as long as wide, 1.2–1.5 times as deep as wide, slightly pointed at apex, papilla absent; upper surface intensely green (not transparent), with 10–100 stomates; pigment cells absent in vegetative tissue. 2n = 30, 40, 42, 44–46, 50, 60, 62 (Europe, Africa).


Phenology: Flowering (very rare) late spring–summer.
Habitat: Mesotrophic to eutrophic, quiet waters in temperate to subtropical regions with relatively mild winters
Elevation: 0–800 m

Distribution

V22 271-distribution-map.jpg

Introduced; Calif., South America (Brazil), w Eurasia, Africa.

Discussion

Wolffia arrhiza was reported from Alberta because of the size of epidermal cells (G. C. D. Griffiths 1988). The plants are within the variation shown by W. columbiana, however.

Selected References

None.

Lower Taxa

None.

... more about "Wolffia arrhiza"
Elias Landolt +
(Linnaeus) Horkel ex Wimmer +
Lemna arrhiza +
Calif. +, South America (Brazil) +, w Eurasia +  and Africa. +
0–800 m +
Mesotrophic to eutrophic, quiet waters in temperate to subtropical regions with relatively mild winters +
Flowering (very rare) late spring–summer. +
Fl. Schles., ed. 3 +
Weedy +, Introduced +  and Illustrated +
Wolffia arrhiza +
species +