The boysenberry is a large, soft, deep maroon-to-purple aggregate berry, a complex bramble hybrid of blackberry, raspberry and loganberry parentage developed in early-20th-century California. Bigger and juicier than a blackberry, it has a sweet-tart, winey, faintly raspberry-perfumed flavour and an intensely staining purple-red juice that has made it a prized fruit for pies, jams, syrups and the theme-park preserves of Knott's Berry Farm.