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 amarum Ribes amarum Ribes amarum is a species of currant known by the common name bitter gooseberry. It is endemic to California, where it is known from mountains, foothills, and canyons. Its habitat includes Chaparral. "Ribes amarum" is a shrub growing to one to two meters (40-80 inches) in height. Nodes along the stem each bear three spines up to a centimeter (0.4 inch) in length. The hairy, glandular leaves are 2 to 4 centimeters (0.8-1.6 inches) long and generally rounded in shape, divided into 3 to 5 rounded toothed lobes. The inflorescence is a solitary flower or raceme of up