Boysenberries

Plural of boysenberry; dark purple berries similar to blackberries that grow on bramble bushes and are sweet with a slightly tart flavor.

Named after Rudolph Boysen, a Californian farmer and horticulturist who developed the hybrid berry in the 1920s by crossing blackberries, raspberries, and loganberries. The fruit became commercially available in the 1930s.