Wolffia arrhiza
Fl. Schles., ed. 3 140. 1857.
Basionym: Lemna arrhiza Linnaeus
Treatment appears in FNA Volume 22. Treatment on page 152.
Revision as of 15:57, 18 September 2019 by FNA>Volume Importer
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
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.