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
Acer nigrum more deeply grooved bark, slightly smaller seeds, and thicker petioles. Hybrids are intermediate in their characteristics. The geographic range of "A. nigrum" is slightly more limited than the sugar maple, encompassing much of the Midwestern United States, portions of the Eastern United States, and the southeast of Canada in southern Ontario. The black maple's mature height ranges from 21 to 34 meters (70 to 110 feet). This species is used similarly to the "A. saccharum", for timber as hard maple, for landscaping, and for maple syrup production. Acer nigrum Acer nigrum (black maple) is a species of maple closely related