Empetrum nigrum subsp. nigrum

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1972, Flora Europaea. Volume 3. Diapensiacea to Myoporaceae, Cambridge: Cambridge University Press : 14

(a) Subsp. nigrum :

Normally dioecious. Stems up to 120 cm, procumbent, sparingly branched, usually rooting; leaves mostly linear-oblong, 2J-5 times as long as wide, usually not grooved beneath. In = 26. Throughout most of the range of the species, but rare in the extreme north and absent from most of the Alps.