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

Ranunculus aquatilis var. diffusus L. With. p.p.
white water-buttercup
Ranunculaceae (Buttercup family)

Introduction to Vascular Plants
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Distribution of Ranunculus aquatilis var. diffusus
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Species Information

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Aquatic, perennial herb, rooting from nodes of lower stems; stems weak, few-branched, creeping or floating, 20-80 cm long, often mat-forming, smooth.
All alternate stem leaves, of two possible types, the floating leaves usually kidney-shaped, 3-parted, 5-8 mm long, 9-15 mm wide, the leaflets elliptic or egg-shaped, margins often notched, unstalked or the stalks 15-40 mm long, the submerged leaves 3 to 5 times 3-dissected, the segments thread-like, the stalks 1-12 mm long; leaves, stalks and stipule-sheaths usually fine-hairy.
Achenes, 10 to 20 in an egg- to globe-shaped head 2-4 mm long, 2-5 mm wide, the achenes egg-shaped, flattened, 1-2 mm long, 0.8-1.4 mm wide, smooth or stiff-hairy; beaks persistent, thread-like, 0.1-1.2 mm long.
The taxonomy of the R. aquatilis complex, at least in North America, remains unclear. The treatment by Whittemore (1997), which we have followed, has included some of our W North American plants with the Eurasian var. aquatilis. The recognition of only two varieties in BC, at least until taxonomic problems are resolved, appears to be the only realistic treatment.

1. Floating leaves simple and dissimilar to the submerged, filiform leaves................. var. aquatilis

1. Floating leaves, if any, similar to the submerged, filiform leaves.................. var. diffusus With.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Ponds and slow-moving streams in the lowland, steppe and montane zones; var. diffusus - common throughout BC, var. aquatilis - infrequent in S BC east of the Coast-Cascade Mountains; var. diffusus - throughout N.A. north of MX, var. aquatilis - circumpolar, N to AK, YT and NT and S to MT, WY, UT, TX, CA and MX; Eurasia, S America.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Ranunculus aquatilis var. diffusus

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) 1117 1117 1117
Slope Gradient (%) 0 0 0
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
8 8 8
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: SBPS(1)


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 not evaluated, unknown or variable.

Synonyms and Alternate Names

Ranunculus amphibius
Ranunculus aquatilis var. subrigidus
Ranunculus circinatus
Ranunculus circinatus var. subrigidus
Ranunculus subrigidus
Ranunculus trichophyllus Chaix
Ranunculus trichophyllus subsp. trichophyllus

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References