Spirodela polyrhiza
Giant duckmeat
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Family: Araceae · Type: Herb · Native
Spirodela polyrhiza (Giant duckmeat) is a native California herb in the Araceae family, recognized by Cosmopolitan aquatic species, largest of California's duckweeds with multiple roots per frond distinguishing it from related genera.
Giant duckmeat is a California native perennial found in northern and central coastal ranges, Sierra Nevada, Central Valley, central Coast, San Francisco Bay Area, Great Basin, and Mojave Desert regions in freshwater habitats at elevations below 2,500 meters. Flowering in August, this aquatic plant produces tiny green to brown flower-like structures on small round-ovate plants. Growing as a floating plant with 5 to 10 millimeters diameter, it develops multiple thin roots through minute scales. Its symmetric plant body features 7 to 12 delicate veins across a smooth upper surface, with winter buds forming in autumn. During seasonal changes, the plant develops specialized reproductive structures that help it survive in aquatic environments.
Identification and appearance
Key characters: Cosmopolitan aquatic species, largest of California's duckweeds with multiple roots per frond distinguishing it from related genera
Habitat and range
Habitat: Freshwater
Elevation: < 2500 m
Outside California: +- worldwide.
Bloom period
Spirodela polyrhiza blooms Aug.
How to tell it apart
vs Lemna: Spirodela has 7-16 roots per frond; Lemna has just 1 root.; vs Nasturtium: Spirodela is a tiny floating disc; Nasturtium has obvious separate leaves and stems above water.; vs Azolla: Spirodela fronds are smooth green discs; Azolla looks like tiny ferns with overlapping scale-like leaves.; vs Landoltia: Spirodela has 7-16 roots; Landoltia has 2-7 roots per frond.; vs Wolffiella: Spirodela has 7-16 roots; Wolffiella is completely rootless and ribbon-shaped.
Frequently asked questions
Is Spirodela polyrhiza native to California?
Yes. Spirodela polyrhiza is native to California (recorded as native).
When does Spirodela polyrhiza bloom?
Spirodela polyrhiza blooms Aug.
What plant family does Spirodela polyrhiza belong to?
Spirodela polyrhiza is in the Araceae family, genus Spirodela.
What habitat does Spirodela polyrhiza grow in?
Spirodela polyrhiza grows in Freshwater.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.