Bermuda buttercup (Oxalis pes-caprae)  

 Wood Sorrel family Oxalidaceae

Description: Bermuda buttercup is a small perennial herb whose shoots arise from a short vertical stem that is attached to a pale brown underground bulb. Each bulb (usually smaller than 2.5 cm in size) is capable of producing over 20 small whitish bulblets each year. The trifoliate (clover-like) leaves arise from an enlarged basal (bottom of the plant) stem tip, and are arranged in a loose basal rosette.   Flowers are bright yellow.  

Bermuda buttercup can form dense mats on the ground, outcompeting native plant species for light and space, and also works to inhibit the germination of native species.   Over the past five years, Bermuda buttercup has been noted to be spread explosively into native dune habitats.

Habitat: Although widespread as a garden weed throughout much of California, Bermuda buttercup has never before been observed invading natural areas in North America until recently. It has been reported in the last several years that Bermuda buttercup is invading native coastal dunes in northern California. Due to its extensive occurrence in lawns and gardens, Bermuda buttercup has the potential to rapidly spread via the production of bulblets and contaminated soils into adjacent natural areas in California and elsewhere.

Distribution: Bermuda buttercup is native to the Cape Region of South Africa and ismost often associated with Mediterranean climates, but also occurs in subtropical and semi-arid regions. In Australia, it is widely invasive throughout the cooler regions, and is pestiferous in all states and territories. It is often seen in disturbed areas and can occur in all soil types. It tends to do best on heavy, well-drained fertile soil, especially in cultivated garden areas.

It was first noted in California in the San Francisco Bay region in the 1960s, especially along the coast. It is currently present in most coastal counties and several inland counties in California.

Flowering period:   In coastal California, Bermuda buttercup generally flowers from late winter to early summer, but fruits and viable seed have not been observed in California.

Eradication note: Bermuda buttercup is difficult to control. Prevent the plant from escaping constrained planters and accessing wildlands. 

Aggressive and repeated methods are required for eradication and can include any single method or combination of the following methods; Waipuna hot foam weed control, manual, mechanical, solarization, and chemical.