Wolffia columbiana
Columbia water meal
(c) Stefan.lefnaer, some rights reserved (CC BY-SA) · licence
Family: Araceae · Type: Herb · Native
Wolffia columbiana (Columbia water meal) is a native California herb in the Araceae family, recognized by very low pore count and transparent green color.
Columbia water meal is a California native perennial found in the Central Coast, San Francisco Bay Area, southern Coast Ranges, southern California, and San Joaquin Valley in freshwater habitats at elevations below 200 meters. Flowering from summer to fall, this tiny aquatic plant produces inconspicuous green flowers. Growing as an extremely minute floating plant just 0.8 to 1.3 millimeters long, it appears as a transparent green spherical body that hovers above the water surface. Its upper surface is mostly convex with a flat center, featuring between 1 to 10 distinctive stomates. This diminutive aquatic plant is so small it resembles a microscopic green dot drifting on the water's surface.
Identification and appearance
Key characters: 4 sympatric species; distinguished by very low pore count and transparent green color
Habitat and range
Habitat: Freshwater
Elevation: < 200 m
Outside California: to Canada, South America
Bloom period
Wolffia columbiana blooms Summer-fall.
How to tell it apart
vs Lemna: Wolffia is spherical and 0.4-1.3 mm; Lemna is disc-shaped, larger, and has a root.; vs Landoltia: Wolffia is spherical, rootless, and 0.4-1.3 mm; Landoltia has 2-7 roots and is much larger.; vs Spirodela: Wolffia is spherical, rootless, and 0.4-1.3 mm; Spirodela has 7-16 roots and is much larger.; vs Wolffiella: Wolffia is spherical like caviar; Wolffiella is flat and ribbon-shaped.
Frequently asked questions
Is Wolffia columbiana native to California?
Yes. Wolffia columbiana is native to California (recorded as native).
When does Wolffia columbiana bloom?
Wolffia columbiana blooms Summer-fall.
What plant family does Wolffia columbiana belong to?
Wolffia columbiana is in the Araceae family, genus Wolffia.
What habitat does Wolffia columbiana grow in?
Wolffia columbiana grows in Freshwater.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.