E-Flora BC: Electronic Atlas of the Flora of British Columbia

Najas flexilis (Willd.) Rostk. & Schmidt
wavy water nymph (nodding waternymph)
Najadaceae (Water-nymph family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #84060)

E-Flora BC Static Map
Distribution of Najas flexilis
Click here to view our interactive map and legend
Details about map content are available here
Click on the map dots to view record details.

Species Information

Click on the image below to view an expanded illustration for this species.

Perennial aquatic herb from a fibrous root; stems much branched, submersed, 30-150 cm long, about 1 mm thick.
Basal leaves lacking; stem leaves linear, 1-3 cm long, about 0.5 mm wide, in nearly opposite pairs, the base expanded for 3-5 mm and more or less sheathing, the margins minutely toothed, tapering continuously to the slender tips.
Inflorescence solitary or a pair of unstalked or nearly unstalked, axillary, unisexual flowers; perianth parts lacking; male flowers with 1-chambered anthers.
Achenes, spindle-shaped, about 3 mm long, smooth.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Blooming Period:
Late Summer
Fruit/Seed characteristics:
Colour: Green
Present from Summer to Fall
Source:  The USDA

Habitat / Range

Ponds and marshes in the lowland, steppe and montane zones; frequent in S BC south of 53degreeN, rare northward in E BC to 55degreeN, rare on the Queen Charlotte Islands, E to NF and S to MA, CT, VA. KY, MO, NE, AZ and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Najas flexilis

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres)
Slope Gradient (%)
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: CDF(5), CWH(12)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is cool temperate & cool mesothermal.

Synonyms and Alternate Names

Caulinia flexilis Willd.
Najas caespitosa (Maguire) Reveal
Najas flexilis subsp. caespitosa Maguire
Najas flexilis var. congesta Farw.
Najas flexilis var. robusta Morong

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References