Blackcurrant can damage both unopened and open flowers when the temperature falls below . The flowers at the base of the strig are more protected by the foliage and are less likely to be damaged. In midsummer the strigs of green fruit ripen to edible berries, very dark purple in colour, almost black, with glossy skins and persistent calyxes at the apex, each containing many seeds. An established bush can produce about 4.5 kilograms (10 pounds) of fruit each year. Plants from Northern Asia are sometimes distinguished as a separate variety, "Ribes nigrum" var. "sibiricum", of which "Ribes cyathiforme" is considered
Ribes quercetorum inches) long and are divided into a few lobes which are toothed or lobed at their tips. The inflorescence is a raceme of 2 or 3 small flowers. Each flower has five reflexed yellow sepals around a tube-shaped ring of smaller cream-colored petals. The fruit is an spherical, edible black berry just under a centimeter (0.4 inch) in diameter. Ribes quercetorum Ribes quercetorum is a species of currant known by the common names rock gooseberry, oak gooseberry and oakwoods gooseberry. It is native to the mountains and hills of California from the San Francisco Bay Area south into Baja California