Ranunculus aquatilis
Ranunculus ranunculinus
renoncule aquatique, water buttercup, water crowfoot, white water butter cup, white water crowfoot, white water crowsfoot, white western buttercup
tadpole buttercup
glabrous.
erect from short caudices, not rooting nodally, glabrous, not bulbous-based.
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.
basal leaf blades ovate to semicircular in outline, ternately or pinnately 2x-compound, 2.4-8.2 × 2-8.5 cm, leaflets parted and again lobed, ultimate segments elliptic to linear, margins entire (or occasionally a lobe reduced to tooth), apex acuminate to rounded.
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.
receptacle glabrous;
sepals spreading or reflexed from base, 3-6 × 1-3 mm, glabrous;
petals (0-)5-6, yellow, 3-8 × 1-3 mm.
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.
hemispheric to globose, 4-5 × 6-7 mm;
achenes 2.2-3.6 × 1.2-1.8 mm, glabrous;
beak filiform, strongly reflexed from base, 0.8-1.5 mm, brittle, often broken.
roots absent.
= 32.
Ranunculus aquatilis
Ranunculus ranunculinus
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
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USDA Plants Database- LBJ Wildflower Center
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