Rubus ursinus aka Pacific Blackberry

Rubus ursinus is a woody shrub in the rose family. Its names include trailing blackberry, western blackberry, and California blackberry. It grows wild in western North America, including Oregon. Its range runs from British Columbia south into Mexico. It also reaches east to central Idaho. Wild plants grow beside streams, in canyons, and on disturbed ground. They often grow in damp, shaded sites.

In gardens, it reaches about 3–5 feet (1–1.5 metres) high. Its spread reaches about 5–8 feet (1.5–2.5 metres). Long canes can extend 10–20 feet (3–6 metres). Young shoots stand upright, then bend toward the ground. Nodes can root where they touch soil. Untrained plants can form dense, prickly thickets. Sources differ on whether leaves persist or fall in winter. Oregon State describes evergreen or partly evergreen plants. The RHS describes plants that lose their leaves.

Slender stems turn from green to brown as they age. Straight prickles cover the canes and also arm leaf stalks. Leaves grow in turn along each stem. Most have three leaflets, though some have five. Upper leaves may be simple rather than compound. Leaflets have lobes and coarse, double teeth along their edges. Their tops are dark green, with paler, hairy undersides. First-year canes bear leaves but no flowers. In their second year, side shoots bear leaves and flowers.

White to pink flowers grow in clusters with hairy, prickly stalks. The RHS also notes their scent. Most plants bear either male or female flowers. Grow both sexes for good fruit crops. The flowers offer pollen to insects. Small fruits turn from red to black as they ripen. Ripe fruit is sweet, juicy, and edible. The central core stays inside the fruit when picked. This shrub suits fruit plots, informal gardens, and wildlife gardens.

Grow it in fertile, moist soil that drains well. It accepts sun or partial shade and varied soil types. Acid, neutral, and alkaline soils all suit it. The RHS rates its cold hardiness H7. Oregon State lists hardiness to USDA Zone 3. Train canes on wires against a sheltered wall or fence. Cut spent fruiting canes to ground level in late autumn. Tie in the new canes grown that summer. Divide plants or layer shoot tips to raise more. Pests seldom cause trouble, but grey mould can occur. Honey fungus is a rare risk.