California Buttercup

Ranunculus californicus
NATIVE

Description (Jepson, PlantID.net)

• Eudicotyledon
  • Eudicots are a major lineage of flowering plants; see family for general characteristics
• Buttercup Family (Ranunculaceae)
• Summer-deciduous perennial herb
• Leaves
  • Basal and alternate (1 leaf at each junction with stem)
  • Deeply-divided into 3 lobes with deeply toothed margins
  • Upper leaves generally reduced
• Flowers
  • Loosely-branching inflorescence (flower arrangement)
  • Each flower grows on a long leafless stem (a scape)
  • 9-17 shiny/waxy yellow overlapping petals
  • Nectary at petal base, with cuplike scale
  • Numerous yellow stamens (male flower parts) and pistils (female flower parts)
  • 5 sepals (usually green, outer flower parts) are folded back
  • Ovary superior (above the attachment of other flower parts)
• Height to 27 in.

Distribution

• Native to California
  • Grows in a wide variety of habitats including chaparral, grasslands, coastal bluffs, woodlands, and moist meadows
  • See Calflora for statewide observations of this plant
• Outside California, grows in Oregon south into Baja California, Mexico
• Grows at elevations to 7,000 ft.

Uses (San Mateo County Parks prohibits removal of any natural material)

• Wildlife
  • Native bees and a variety of other insects, e.g. thrips and flies, are attracted to the flowers
  • Bees are the primary pollinator (COSEWIC 2008)
• Native people
  • Collected the seeds for pinole (Anderson 2005)
    • Pinole is a general term for various flours made from the ground, toasted seeds of wildflowers and grasses, eaten dry or moistened and shaped into balls or cakes
    • “Pinole” is a Hispanic version of an Aztec word
• CAUTION – the ingestion of raw seeds, sap, flowers, or leaves results in moderate but non-life-threatening symptoms (e.g. nausea, vomiting)

Name Derivation

• Ranunculus (ra-NUN-ku-lus) – from the Latin for “little frog,” referring to the genus growing in moist areas

Notes

• The glossy-yellow petals of buttercups (Ranunculus species) have structural as well as pigmented color
  • Petals consist of 3 layers: a yellow pigment layer, an air layer, and a starch layer (Vignolini 2011)
    • Layers produce a highly directional, reflective optical response—a flash—which may lure in pollinators
  • Flowers follow the sun (heliotropic) and become bowl-shaped (paraboloid) in low temperatures (van der Kooi 2017)
    • Petals reflect light to the flower’s center, warming reproductive organs and attracting pollinators, who are often found hanging out in the sunny bowl
  • Structural color, seen in birds with blue feathers, is rare in plants

ID Tips

• When not blooming, may be confused with royal larkspur (Delphinium variegatum), which has more deeply cut leaves than California buttercup

At Edgewood

• Found in many habitats, including grasslands and woodlands
  • See iNaturalist for observations of this plant
• Flowers February – April

See General References

Specific References

Anderson, M.K. 2005. Tending the Wild. University of California, Berkeley.

COSEWIC. 2008. California buttercup (Ranunculus californicus): COSEWIC assessment and status report 2008. Prepared by M. Fairbarns, B. Klinkenberg, and R. Kinkenberg. Committee on the Status of Endangered Wildlife in Canada, Ottawa.

van der Kooi, C. J., et al. 2017, Feb. 22. Functional optics of glossy buttercup flowers.  Journal of the Royal Society Interface. The Royal Society Publishing.

Vignolini, J., et al. 2011, Dec. 14. Directional scattering from the glossy flower of Ranunculus: How the buttercup lights up your chin. Journal of the Royal Society Interface. The Royal Society Publishing.