There are three varieties of mulberry. The white and the black types are of Asian origin, while the red hails (mainly) from the eastern United States. Although both black and white mulberry trees are cultivated commercially in China and surrounding countries (primarily for their leaves, which are used a food source for silkworms), they grow wild only in Europe. The trees, of medium size, are bushy and somewhat disheveled-looking, yet attractive in their own way. Mulberries somewhat resemble blackberries in appearance, but they grow differently; mulberries develop in clusters rather than individually. The berries must be left to become fully ripe before they are picked. However, instead of being picked off the tree, they are typically allowed to fall to the ground and are gathered there. For this reason, mulberry trees are typically planted in grassy areas. Fully ripe mulberries are both sweet and sour in taste and, when unripe, are so sour as to be practically inedible. In the United States, the berries are used for jams and mulberry wine, sorbets, and ice creams.