Empetrum nigrum, crowberry, black crowberry, or, in western Alaska, blackberry, is a flowering plant species in the heather family Ericaceae with a near circumboreal distribution in the northern hemisphere. It is also native in the Falkland Islands. It is usually dioecious, but there is a bisexual tetraploid subspecies, Empetrum nigrum ssp. hermaphroditum, that occurs in more northerly locations and at higher altitude. The metabolism and photosynthetic parameters of Empetrum can be altered in winter-warming experiments.