Very large bramble fruit, usually considered, along with the loganberry and the youngberry, a variety of blackberry ( Rubus ursinus ).
The dark, reddish-black fruit is especially valued for canning and preserving. It is grown chiefly in the southern and southwestern U.S. and on the Pacific Coast from southern California into Oregon. It was developed in the early 1920s by Rudolph Boysen (1895–1950) of Napa, Cal.