The Jostaberry is a cross between the black currant Ribes nigrum, the North American coastal black gooseberry Ribes divaricatum and the European gooseberry Ribes uva-crispa.
The flowers are hermaphrodite and the plant is self-fertile following insect pollination which then turn to small, round, plump fruits.
Jostaberries have a tangy-sweet flavor that seems to be is a mix of grape, blueberry, and kiwi-fruit all rolled into one - no wonder they are becoming very popular.
These are hardy plants that can stand frosts as well as summer heat, but do actually need to experience regular winter cold in order to keep producing good fruit.
Just make sure that frosts have passed before they flower in early spring.