Lemna minor
Smaller duckweed
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Family: Araceae · Type: Herb · Native
Lemna minor (Smaller duckweed) is a native California herb in the Araceae family, recognized by flat lower surface, symmetric base and tip, and lack of air spaces.
Smaller duckweed is a native perennial found in coastal and inland regions of California, including the North Coast, Central Coast, San Francisco Bay Area, southern California, Mojave Desert, and Great Valley in freshwater habitats at elevations below 2,000 meters. Flowering in August, this tiny aquatic plant produces small, inconspicuous flowers. Growing in clusters of 2 to 3 individual plants, it forms glossy green elliptic-obovate fronds 2 to 5 millimeters long with smooth upper surfaces. Its symmetrical leaf-like structures have flat lower surfaces with subtle air spaces, creating a delicate floating mat on water surfaces. The plant's compact, uniform appearance allows it to thrive in various freshwater environments, from slow-moving streams to pond edges.
Identification and appearance
Key characters: Co-occurs with 6 species; key features are flat lower surface, symmetric base and tip, and lack of air spaces
Habitat and range
Habitat: Common. Freshwater
Elevation: < 2000 m
California counties: Riverside, Lake, San Bernardino, Ventura, Mono, Plumas, Los Angeles, Napa, Santa Cruz, San Diego, Lassen, Modoc, Shasta, Tehama, Inyo, Merced, Mendocino, Fresno, Marin, Sonoma, Sierra, Madera, San Luis Obispo, Kern, Humboldt, Monterey, Nevada, Mariposa, San Francisco, San Mateo, Santa Barbara, Sacramento, San Joaquin, Butte, Siskiyou, Contra Costa, Del Norte, Placer, Yolo, Alpine
Outside California: worldwide
Bloom period
Lemna minor blooms Aug.
How to tell it apart
vs Azolla: Lemna is smooth bright green with a single root; Azolla is feathery textured, often reddish, with no visible roots.; vs Callitriche: Lemna floats as separate tiny discs; Callitriche has distinct stems with opposite leaves forming small rosettes.; vs Nasturtium: Lemna is a tiny rootless-looking disc; Nasturtium has obvious stems, compound leaves, and grows rooted in mud.; vs Spirodela: Count the roots: Lemna has exactly one root per disc, Spirodela has multiple roots clustered together beneath each disc.; vs Landoltia: Count the roots: Lemna has one root per disc, Landoltia has 2-7 roots hanging down like a tiny broom.
Frequently asked questions
Is Lemna minor native to California?
Yes. Lemna minor is native to California (recorded as native).
When does Lemna minor bloom?
Lemna minor blooms Aug.
Where in California does Lemna minor grow?
Lemna minor occurs in Riverside, Lake, San Bernardino, Ventura, Mono, Plumas, Los Angeles, Napa and other counties, at elevations of < 2000 m.
What plant family does Lemna minor belong to?
Lemna minor is in the Araceae family, genus Lemna.
What habitat does Lemna minor grow in?
Lemna minor grows in Common. 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.