The plant photographed below grows in parts of Tilden park, Berkeley California. The flower photo was taken about 7 weeks ago and the fruit photo just a few days ago, note yet ripe.
I initially assumed it was Ribes uva-crispa, gooseberry, however now I am wondering if it could be the Ribes divaricatum, the American Worchesterberry which, as the name partially suggests, is native to N. America. Readers, please let me know if you know.
R. uva crispa is a long-lived deciduous shrub with spiny branches. Ribes uva-crispa produces a shiny semi-translucent berry, born singly or in pairs, green or often yellow, red or purple (depending on the cultivar). The Gooseberry is closely related to the aforementioned American Worcesterberry (R divaricatum) and the current gooseberry (R. hirtellum).
The gooseberry is a widely distributed throughout Europe and Asia. Cultivation of the fruit was already underway in the fifteenth century, apparently becoming quite popular during the eighteenth century when a wide range of cultivars were developed. Today commercial production is centered in western central and eastern Europe, Germany being the largest producer.
The fruit are a fairly good source of vitamin C (15-35mg per 100g) and can be eaten fresh or processed into a variety of jams, juices, preserves, etc.
The plant and its close relatives are readily propagated from cuttings. Plants require a temperate climate and cold winters.
Click photos to enlarge.