Ranunculus rhomboideus
Ranunculus aquatilis
Labrador buttercup, prairie buttercup, prairie crowfoot
renoncule aquatique, water buttercup, water crowfoot, white water butter cup, white water crowfoot, white water crowsfoot, white western buttercup
slender, 0.8-1.8 mm thick.
erect, 5-22 cm, pilose or occasionally glabrous, each with 3-12 flowers.
glabrous.
laminate and filiform-dissected; laminate leaf blades reniform, 3-parted, 0.4-1.1 × 0.7-2.3 cm, segments obovate or fan-shaped, shallowly cleft, margins crenate;
filiform-dissected leaves with stipules gradually tapering upward, connate for their whole length.
persistent, blades ovate to rhombic, undivided or rarely innermost 3-parted, 1.1-5.3 × 0.9-3.6 cm, base obtuse, margins crenate with 5 crenae, apex rounded.
pedicels pilose;
receptacle pilose;
sepals 4-6 × 1.5-3 mm, abaxially pilose, hairs colorless;
petals 5, 6-8 × 2-4 mm;
nectary scale glabrous.
receptacle hispid, rarely glabrous;
sepals spreading or reflexed, 2-4 × 1-2 mm, glabrous;
petals 5, 4-7 × 1-5 mm;
style 0.1-0.8 mm.
usually recurved.
depressed-globose, 4-6 × 5-7 mm;
achenes 1.8-2.2 × 1.2-1.8 mm, glabrous;
beak slender, curved, 0.2-0.3 mm.
hemispheric to ovoid, 2-4 × 2-5 mm;
achenes 1-2 × 0.8-1.4 mm, glabrous or hispid;
beak persistent, filiform, 0.1-1.2 mm.
= 16.
Ranunculus rhomboideus
Ranunculus aquatilis
In addition to the range given above, L. D. Benson (1948) cited nineteenth-century specimens from Quebec, New York, Massachusetts, and Rhode Island. No modern specimens have been seen from those areas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
Ranunculus aquatilis is very variable. In the past it has often been treated as three or four species and many varieties. These segregate taxa have been based on the size, petiolation and rigidity of the leaves (now known to be primarily under environmental control), petal size and curvature of the fruiting pedicel (both sometimes variable along single stem), and number of achenes per head and length of achene beak (which vary continuously and are not correlated with one another). Unless reliable characters can be found, only two of the taxa recognized in older floras can be maintained.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaves of 2 types: laminate and filiform-dissected; w North America. | var. aquatilis |
1. Leaves all filiform-dissected; widespread. | var. diffusus |
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
