Frogbit Family, Naiad Family, or Water-nymph Family, Tapegrass Family, Waterweed Family
Najadaceae [FNA22, HC]
Vallisneriaceae [Abrams]
7 genera
10 species
1 subspecies and varieties
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Scientific name
Common name
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Egeria densaBrazilian waterweed, South American waterweed
Distribution: Introduced from Washington to California, and across the southern half of the United States to the Atlantic; occasional west of the Cascades in Washington and Oregon
Habitat: Commonly used in aquaria, often escaping
Origin: Introduced from South America
Flowers: July - September
Elodea canadensisCanadian, Rocky Mountain, or common waterweed
Distribution: Throughout most of the United States
Habitat: Common in slow-moving, often alkaline water, in the Pacific Northwest
Origin: Native
Flowers: July - September
Elodea nuttalliiNuttall's waterweed, western waterweed
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California and Nevada, east to the Great Plains, midwestern U.S., and northeastern North America.
Habitat: Fresh to slightly brackish water of streams, rivers, lakes, ponds, and backwaters at low to middle elevations.
Origin: Native
Flowers: July - September
Hydrilla verticillatahydrilla, water thyme
Origin: Introduced from Eurasia
Hydrocharis morsus-ranaefrogs's-bit
Origin: Introduced
Limnobium laevigatumfrogbit
Distribution: Known from Pacific County in Washington; also known from California and eastern U.S.
Habitat: Lowland ponds, where found floating on water's surface.
Origin: Introduced
Flowers: June-September
Najas canadensisCanadian water nymph
Origin: Native
Najas flexilisor slender naias, slender nymph, wavy water nymph
Distribution: Distributed on both sides of the Cascades in Washington; Alaska south to California, east to Arizona, and across the northern half of North America.
Habitat: Fresh to slightly brackish water.
Origin: Native
Flowers: April-August
Najas guadalupensisGuadalupe water-nymph
Distribution: Oregon south to Baja California, east to the Atlantic Coast.
Habitat: Fresh water.
Origin: Native
Flowers: June - August
ssp. guadalupensis – Guadalupe naias, common water nymph, Guadalupe nymph
Vallisneria americanawild celery, American eelgrass, tapegrass
Distribution: Native from Quebec to Texas and Florida; introduced in Dry Falls Coulee, Grant County, and several lakes west of the Cascades in Washington; also in Oregon and Idaho
Habitat: Ponds, lakes and quiet streams
Origin: Introduced from eastern North America
Flowers: July - September