Egeria densa
Brazilian water weed
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Family: Hydrocharitaceae · Type: Herb · Not Native
Conservation status: Cal-IPC Yes
Egeria densa (Brazilian water weed) is a non-native California herb in the Hydrocharitaceae family, recognized by South American genus introduced as aquarium plant; aggressive colonizer of California waterways.
Brazilian water weed is a naturalized perennial found in the Sierra Nevada Foothills, Great Valley, San Francisco Bay Area, San Jacinto Mountains, and Great Basin in streams, ponds, and sloughs at elevations below 2,200 meters. Flowering from July to August, this aquatic plant produces white flowers with rounded petals 8 to 10 millimeters long. Growing with slender stems 2 to 3 millimeters thick, it forms dense underwater vegetation. Its leaves are narrowly oblong, 1.2 to 4 centimeters long, 2 to 5 millimeters wide, with finely serrated edges that recurve slightly. In aquatic environments, the plant can form extensive underwater meadows that provide habitat for aquatic organisms.
Identification and appearance
Key characters: South American genus introduced as aquarium plant; aggressive colonizer of California waterways
Habitat and range
Habitat: Streams, ponds, sloughs
Elevation: < 2200 m
California counties: Mono, Riverside, San Joaquin, Kern, Nevada, Los Angeles, Marin, Sutter, Napa, San Francisco, Santa Clara, Tuolumne, Sacramento, Fresno, Calaveras, Placer, Shasta, Sonoma, Merced, Madera, Imperial, Contra Costa, Butte, Santa Cruz, San Luis Obispo, San Diego, Siskiyou, El Dorado, Stanislaus
Outside California: to eastern United States, Europe, native to South America
Bloom period
Egeria densa blooms Jul-Aug.
Conservation status
Cal-IPC Yes
How to tell it apart
vs Najas: Egeria has large leaves (1.2-4 cm) and showy white flowers; Najas has tiny leaves and no petals.; vs Hydrilla: Egeria leaves are large (1.2-4 cm long); Hydrilla leaves are much smaller (under 1.5 cm).; vs Elodea: Egeria has large leaves (1.2-4 cm) and flowers with 8-10mm petals; Elodea has tiny leaves and inconspicuous flowers.; vs Ottelia: Egeria is fully submerged with whorled leaves; Ottelia has floating leaf rosettes and emergent flowers.; vs Limnobium: Egeria is submerged with whorled narrow leaves; Limnobium has round floating leaves on spongy stalks.
Frequently asked questions
Is Egeria densa native to California?
No. Egeria densa is not native to California (recorded as not native).
When does Egeria densa bloom?
Egeria densa blooms Jul-Aug.
Where in California does Egeria densa grow?
Egeria densa occurs in Mono, Riverside, San Joaquin, Kern, Nevada, Los Angeles, Marin, Sutter and other counties, at elevations of < 2200 m.
What plant family does Egeria densa belong to?
Egeria densa is in the Hydrocharitaceae family, genus Egeria.
Is Egeria densa invasive in California?
Egeria densa is listed by Cal-IPC with an invasiveness rating of Yes.
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.