Rubus ursinus is a North American species of blackberryordewberry, known by the common names California blackberry, California dewberry, Douglas berry, Pacific blackberry, Pacific dewberry and trailing blackberry.
Rubus ursinus is a wide, mounding shrub or vine, growing to 0.61–1.52 metres (2–5 feet) high, and more than 1.8 m (6 ft) wide.[3] The prickly branches can take root if they touch soil, thus enabling the plant to spread vegetatively and form larger clonal colonies.
The leaves usually have 3 leaflets but sometimes 5 or only 1, and are deciduous. The plant is dioecious, with male and female plants on separate plants, also unusual for the genus. As with other Rubus, the canes are typically vegetative the first year, and reproductive in the second.
The flowers are white with narrower petals than most related species, and have a fragrance.[4] The sweet, very aromatic, edible fruits are dark purple, dark red, or black and up to 2 centimetres (3⁄4 inch) in length.[5]
Acultivar of this species named the 'Aughinbaugh' blackberry was a parent of the loganberry. R. ursinus is also a second-generation parent of the boysenberry and the marionberry, or 'Marion' blackberry.[10]
'Wild Treasure' has the fruit size and flavor of the wild species, but without prickles, and the berries are machine harvestable. It was released by the U.S. Department of Agriculture's Agricultural Research Service in 2010, and is a hybrid between a selection of R. ursinus and 'Waldo' (another cultivar that is a second-generation descendant of the marionberry that has no prickles).
To set large fruit, the plant needs consistent amounts of moisture.[14] Otherwise it is moderately drought tolerant when established. Seed size seems to be related to fruit "cell" size, and the smallest fully formed berries (about 1 cm or 3⁄8in) are most highly prized. These are sometimes called "little wild blackberries".
Diverse wildlife eat the berries, including songbirds, deer, bear, and other large and small mammals.[3] It is of notable pollinator and nesting material value for native bee and bumble bee species.[3] This blackberry species is a larval food source for Papilio rutulus (the western tiger swallowtail butterfly), Nymphalis antiopa (the mourning cloak butterfly), Strymon melinus (the gray hairstreak butterfly), and Celastrina ladon (the spring azure butterfly).[13]
