The blackberry is an aggregate fruit from a bramble bush, genus Rubus in the rose family Rosaceae. It is a widespread and well known group of several hundred species, many of which are closely related apomictic microspecies native throughout the temperate Northern hemisphere.Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.

Growth and anatomical description

Blackberries are perennial plants which typically bear biennial stems ("canes") from the perennial root system.University of Georgia, Blackberries and Raspberries (Rubus spp.). Retrieved on 2008-03-26.

In its first year, a new stem grows vigorously to its full length of 3-6 m, 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 stem does not grow longer, but the flower buds break to produce flowering laterals, which bear smaller leaves with three or five leaflets. First and second year shoots are usually spiny with numerous short curved very sharp thorns (thornless cultivars have been developed purposefully).

Unmanaged mature plants form a tangle of dense arching stems, the branches rooting from the node tip when they reach the ground. Vigorous and growing rapidly in woods, scrub, hillsides and hedgerows, blackberry shrubs tolerate poor soils, readily colonizing wasteland, ditches and vacant lots.Blamey, M. & Grey-Wilson, C. (1989). Flora of Britain and Northern Europe. ISBN 0-340-40170-2.

The flowers are produced in late spring and early summer on short racemes on the tips of the flowering laterals. Each flower is about 2-3 cm in diameter with five white or pale pink petals. The newly developed primocane produces flowers and fruits on the new growth.

The early flowers often form more drupelets than the later ones. This can be a symptom of exhausted reserves in the plant's roots, marginal pollinator populations, or infection with a virus such as Raspberry bushy dwarf virus. Even a small change in conditions, such as a rainy day or a day too hot for bees to work after early morning, can reduce the number of bee visits to the flower, thus reducing the quality of the fruit. The drupelets only develop around ovules that are fertilized by the male gamete from a pollen grain.

In botanical terminology, the fruit is not a berry, but an aggregate fruit of numerous drupelets ripening to black or dark purple, the "blackberry".

Blackberry leaves are also a food for certain caterpillars. See List of Lepidoptera that feed on Rubus

Cultivation and uses

Primary cultivation takes place in the state of Oregon located in the United States of America. Recorded in 1995 and 2006: to of blackberries, producing 42.6 to 41.5 million pounds, making Oregon the leading blackberry producer in the world.