California Invasive Plant Council

Oxalis pes-caprae

Common names: Bermuda buttercup; buttercup oxalis; sour grass

Oxalis pes-caprae (buttercup oxalis, Bermuda buttercup, yellow oxalis) is a low-growing perennial (family Oxalidaceae) found along the coast of California, in the Coastal Ranges, and in the Sacramento Valley. Buttercup oxalis occurs in coastal dunes, scrub, oak woodlands, gardens, turf, urban areas, orchards and agricultural fields. Buttercup oxalis was introduced as an ornamental landscape plant from South Africa. Although buttercup oxalis does not produce seeds, it is difficult to control because of its ability to form many persistent bulbs. Cultivation may be an effective control if carried out when the plants are just beginning to flower.

Cal-IPC Rating: Moderate

Cal-IPC Assessment

Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.

Weed Management Notes

• Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.

Cal-IPC Newsletter Articles

• Oxalis pes-caprae control trials. Stringer, Lew. Vol 24, Issue 2
• Oxalis pes-caprae. Sigg, Jake. Vol 11, Issue 1
• Portrait of an invader II: The ecology and management of Carpobrotus edulis. Albert, Marc E.. Vol 03, Issue 2

Cal-IPC Symposium Presentations

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

• Mapping weeds and rare plants to inform management and conservation in the Zaca and Jesusita fires. Calloway, Stephanie; Schneider, Heather; Knapp, Denise (2018)
• Management of a coastal bluff community invaded by Oxalis pes-caprae with low concentrations of glyphosate. Reed, Lewis; Olarnik, Suzanne; Hyland, Tim (2017)
• Management of Bermuda buttercup (Oxalis pes-caprae) in the Peninsula Watershed of the San Francisco Public Utilities Commission. Thomas, Don (2017)

Other Oxalis pes-caprae Information

• CalPhotos - Images of plants taken mostly in California.
• Calflora - See the distribution of this species on Calflora's map of California.
• CalWeedMapper - Distribution information with ability to determine regional priorities.
• Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
• USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.
• Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.