Blackberries are compound fruits that grow wild and cultivated throughout the world. The blackberry is a distant cousin to the rose, and like the rose it produces flowers and fruit on thorny canes. The primary characteristic of blackberry fruit is that it is an aggregate fruit, meaning that it is composed of a cluster of smaller fruit known as drupelets. Because blackberries are the most well-known of the aggregate fruits, other aggregate berries often are compared to the blackberry.
There are three species of mulberry plants in the world: black mulberry, white mulberry and red mulberry. The red mulberry is native to the United States and very cold-hearty, while the other two varieties are less hearty and typically are grown in climates warmer than USDA Zone 7. The berries are multi-segmented and resemble a swollen blackberry. Black mulberry fruits are large, plump and juicy with a sweet-tart flavor. Red mulberries are a deep red that is almost black in color. Their flavor is considered slightly inferior to black mulberries. White mulberry fruit may be black, lavender or white. They are sweet without being tart.
The Black Raspberry, also known as the black cap, is a cousin to the blackberry and raspberry. Unlike raspberries, black raspberries grow well in hot, humid regions. The berries are high in anthocyanins, which are the same plant hormones that give roses their tint and make some deciduous leaves turn red in the winter. Because of the purple-black color of black raspberries, some people mistakenly call them blackberries. However, the taste of black raspberries is unlike raspberries and blackberries.
The boysenberry is a hybrid of a hybrid. The plant was first created as a cross between blackberries, raspberries and loganberries -- which are a cross of blackberries and raspberries. The resulting plants produce plump, multi-segmented fruit that is high in anthocyanins. The taste is similar to raspberries but slightly tarter. The berry was introduced through Knotts Berry Farm, and its success as a jam and jelly fruit helped to make the farm into a large commercial success.
Dewberries resemble blackberries so closely that even the leaves of dewberry canes can resemble blackberry canes. There is little difference between the dewberry and blackberry fruit, and the two can be used interchangeably in pies, jelly and jam. The only difference between the two berries is the way in which they grow. Dewberries grow on vines rather than canes. These vines sprawl along the ground and rarely grow taller than 2 feet.