- Family: Ranunculaceae
- Common Names: western buttercup
- Synonyms/Misapplications: Ranunclus eisenii, R. occidentalis var. eisenii, R. o. var. rattanii, R. o. var. typicus
- Codon: RANOCC
|Genus:|| Ranunculus L.|
|Species:|| Ranunculus occidentalis Nutt.|
|Subspecies:|| Ranunculus occidentalis var. occidentalis Nutt.|
|Ranunculus occidentalis range|
Erect perennial with stiff hairs emerging from slender fibrous roots, stems usually hollow, 1.5-4 dm tall.
Basal leaves long-petiolate, the blades 2-3.5 cm. long, deeply lobed into 3 segments, the lobes with coarse, rounded teeth; cauline leaves alternate, more deeply dissected, reduced upward to the entire bracts.
Sepals strongly reflexed along a well-defined fold, bears 5-petaled yellow flowers with many pistils.
The fruit is an aggregate of pumpkin-seed shaped achenes. The styles jutting out from the ends of achenes are less hooked than R. uncinatus. Leaves are also more pubescent and lighter in color than R. uncinatus.
April-June, right before and among the Camas.
Southwest BC south, west of the Cascades, and in Columbia River Gorge, to California.
Moist to well-drained soil, meadows and open woods, mostly west Cascades, Alaska to California, east to Alberta and northeast Oregon.
Ecological: Adult Mardon Skippers (Polites mardon) feed on the nectar of R. occidentalis, among other flowers. 
First Nations: The juice from the flowers used as a poison. Seeds cooked and used as piñole either on their own or mixed with other seeds. The seed must be parched in order to remove an acrid principle.
Seed sample from: 2011
Average Measurement: 3.5 x 2.6 x 1
Measurement Range: L: 3 - 4, W: 2 - 3, D: 0.75 - 1.25
Shape: Seed surface is rounded, tapering off to a style that is opposite hilum, but off centered from it.
Additional structures: Style generally 1 – 2 mm long.
Color: Seeds are brown, tending toward a lighter brown or tan at edges of seed surface.
Surface: Seeds are papillose with some small ridges around the surface edges.
Basic Explanations and Assumptions:
The dimensions for the seeds are length x width x depth. The location of the hilum is used as the base of the seed, and the length is measured from hilum to the opposite apex. Where a style is present, the length is measured from the hilum to the bottom of the style. Width is measured at a right angle to the length at the widest part. Depth is measured at a right angle to the intersection of height and width lines.
Measurements included are the mean average for each measurement of ten separate seeds.
All measurements in millimeters unless otherwise noted.
- WTU Herbarium, Burke Museum, & University of Washington. Retrieved from https://biology.burke.washington.edu/herbarium/imagecollection/taxon.php?Taxon=Ranunculus%20occidentalis%20var.%20occidentalis
- Hitchcock, C. L., Cronquist, A., Giblin, D., & Legler, B. et al. (2018). Flora of the Pacific Northwest: an illustrated manual. Seattle: University of Washington Press.
- Bowcutt, F., & Hamman, Sarah. (2016). Vascular plants of the South Sound prairies (First ed.). Olympia, Washington: The Evergreen State College Press.
- Native American Ethnobotany Database. Retrieved from http://naeb.brit.org/uses/search/?string=ranunculus+occidentalis