The blackberry is an edible fruit produced by many species in the genus Rubus in the family Rosaceae, hybrids among these species within the subgenus Rubus, and hybrids between the subgenera Rubus and Idaeobatus. The taxonomy of blackberries has historically been confused because of hybridization and apomixis, so that species have often been grouped together and called species aggregates. For example, the entire subgenus Rubus has been called the Rubus fruticosus aggregate, although the species R. fruticosus is considered a synonym of R. plicatus. Rubus armeniacus ("Himalayan" blackberry) is considered a noxious weed and invasive species in many regions of the Pacific Northwest of Canada and the United States, where it grows out of control in urban and suburban parks and woodlands. Description What distinguishes the blackberry from its raspberry relatives is whether or not the torus (receptacle or stem) "picks with" (i.e., stays with) the fruit. When picking a blackberry fruit, the torus stays with the fruit. With a raspberry, the torus remains on the plant, leaving a hollow core in the raspberry fruit. The term bramble, a word referring to any impenetrable thicket, has in some circles traditionally been applied specifically to the blackberry or its products, though in the United States it applies to all members of the genus Rubus. In small parts of the western US, the term caneberry is used to refer to blackberries and raspberries as a group rather than the term bramble. Briar or brier is also sometimes used to refer to the plant, though this name is used for other thorny thickets (such as Smilax) as well. The usually black fruit is not a berry in the botanical sense of the word. Botanically it is termed an aggregate fruit, composed of small drupelets. It is a widespread and well-known group of over 375 species, many of which are closely related apomictic microspecies native throughout Europe, northwestern Africa, temperate western and central Asia and North and South America. Botanical characteristics Blackberries are perennial plants which typically bear biennial stems ("canes") from the perennial root system. In its first year, a new stem, the primocane, grows vigorously to its full length of (in some cases, up to ), arching or trailing along the ground and bearing large palmately compound leaves with five or seven leaflets; it does not produce any flowers. In its second year, the cane becomes a floricane and the stem does