Najas flexilis
Slender water-nymph, Slender Water-Nymph
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Family: Hydrocharitaceae · Type: Herb · Native
Najas flexilis (Slender water-nymph) is a native California herb in the Hydrocharitaceae family, recognized by smooth vs. prickled stems and leaf tooth count.
Slender water-nymph is a California native annual found in the Klamath Ranges and northern coastal ranges in ponds and lakes at elevations below 1,500 meters. Flowering from June to September, this delicate aquatic plant produces small, inconspicuous flowers with distinctive leaf margins. Growing as a monoecious underwater plant with slender stems, it has fine, translucent leaves with 35 to 80 tiny teeth along each margin. Its leaves have an acute tip with 1 to 2 additional small teeth and a rounded leaf sheath, creating a delicate, intricate underwater structure. The tiny seeds are 0.2 to 1.2 millimeters wide, with a smooth and shiny coat that aids in dispersal through aquatic environments.
Identification and appearance
Key characters: 1 sympatric species; distinguished by smooth vs. prickled stems and leaf tooth count
Habitat and range
Habitat: Uncommon. Ponds, lakes
Elevation: < 1500 m
Outside California: to Canada, northeastern United States, northern Europe
Bloom period
Najas flexilis blooms Jun-Sep.
How to tell it apart
vs Hydrilla: Najas leaves have obvious teeth along margins; Hydrilla has spiny bumps on the leaf midrib underneath.; vs Elodea: Najas leaves are arranged opposite or in whorls of many; Elodea has 2-3 leaves at stem base, 3-7 higher up.; vs Egeria: Najas has tiny leaves under 1.5 cm; Egeria leaves are much larger (1.2-4 cm long).; vs Ottelia: Najas is completely submerged with tiny flowers; Ottelia has floating leaves and showy white flowers above water.; vs Limnobium: Najas is fully submerged with narrow toothed leaves; Limnobium has round floating leaves on spongy stalks.
Frequently asked questions
Is Najas flexilis native to California?
Yes. Najas flexilis is native to California (recorded as native).
When does Najas flexilis bloom?
Najas flexilis blooms Jun-Sep.
What plant family does Najas flexilis belong to?
Najas flexilis is in the Hydrocharitaceae family, genus Najas.
What habitat does Najas flexilis grow in?
Najas flexilis grows in Uncommon. Ponds, lakes.
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.