Ranunculus aquatilis
Ranunculus macauleyi
renoncule aquatique, water buttercup, water crowfoot, white water butter cup, white water crowfoot, white water crowsfoot, white western buttercup
Rocky Mountain buttercup
slender, 0.7-1.3 mm thick.
glabrous.
erect from short caudices, 6-15 cm, glabrous or sometimes pilose, each with 1-2 flowers.
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 narrowly elliptic to lanceolate or oblanceolate, undivided, 1.5-4.5 × 0.5-1.1(-2.8) cm, base acute or long-attenuate, margins entire except for apex, apex truncate or rounded and 3(-5)-toothed.
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.
pedicels glabrous or brown-pilose;
receptacle glabrous;
sepals 6-12 × 2.5-8 mm, abaxially densely brown-pilose;
petals 5(-8), 10-19 × 6-17 mm;
nectary scale glabrous.
usually recurved.
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.
ovoid or cylindric, 5-10 × 4-5.5 mm;
achenes 1.5-1.7 × 1.2-1.3 mm, glabrous;
beak slender, straight or recurved, 0.5-1.5(-2.2) mm.
Ranunculus aquatilis
Ranunculus macauleyi
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.)
The type specimen of Ranunculus macauleyi var. brandegeei L. D. Benson, from the Sangre de Cristo Mountains, Colorado, differs from typical R. macauleyi in its tall stem, broad, crenate-laciniate leaves, and sepals with pale or transparent hairs. These characteristics are suggestive of R. inamoenus, and the plant may be of hybrid ancestry.
(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
