Lemna aequinoctialis
Lesser duckweed
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Family: Araceae · Type: Herb · Native
Lemna aequinoctialis (Lesser duckweed) is a native California herb in the Araceae family, recognized by size, base/tip asymmetry pattern, and habitat restriction to hot regions.
Lesser duckweed is a native perennial found in northern Sierra Nevada Foothills, Central Valley, Central Coast, southern California Coast, and Desert Sonoran regions in freshwater habitats at elevations below 200 meters. Flowering from September to December, this aquatic plant produces small light green fronds with distinctive minute bumps at the tip and root attachment. Growing in small colonies typically two to three and a half millimeters long, these obovate-elliptic fronds have an asymmetric base and symmetric tip. Its delicate fronds are light green with a smooth lower surface, forming unique floating clusters in still water. The seed surfaces display cross-lined textures between subtle ribs, creating intricate patterns within its tiny aquatic structure.
Identification and appearance
Key characters: Co-occurs with 6 species; key features are size, base/tip asymmetry pattern, and habitat restriction to hot regions
Habitat and range
Habitat: Freshwater in hot regions
Elevation: < 200 m
Outside California: worldwide
Bloom period
Lemna aequinoctialis blooms Sep-Dec.
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 aequinoctialis native to California?
Yes. Lemna aequinoctialis is native to California (recorded as native).
When does Lemna aequinoctialis bloom?
Lemna aequinoctialis blooms Sep-Dec.
What plant family does Lemna aequinoctialis belong to?
Lemna aequinoctialis is in the Araceae family, genus Lemna.
What habitat does Lemna aequinoctialis grow in?
Lemna aequinoctialis grows in Freshwater in hot regions.
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.