Refrigerate the rest, unwashed, layered between paper towels. Picked fully ripe, they are fully soft, fragrant, sweet, and best eaten raw. One form of blackberry or another is in season from June through mid September. Select all forms as for red raspberries. They do not last for more than a day.
Boysenberries are long, maroon, and almost seedless.
Their flavor is sweet-tart, rather like raspberries, with a distinctive fragrance. They are of excellent quality and berries may be a cross of red raspberry and blackberry. Most people who have tasted them think these large, juicy, slightly tart, burgundy-red berries are the finest flavored of all berries and the best for cooking. Marion is the most popular blackberry, especially fine in desserts. Syvan berries are a cross between boysenberry and marion berry.