Himalayan blackberry (Rubus discolor) is mostly a biennial plant, growing on disturbed sites, along roadsides and rights-of-ways, in pastures, along river and stream banks, fresh-water wetlands, riparian areas, forest edges, and wooded ravines. They are currently distributed on the Lower Mainland, Sunshine Coast, Fraser Valley, Gulf Islands, central to southern Vancouver Island, Queen Charlotte Islands, the Okanagan, and the West Kootenay areas.
Himalayan blackberry has petite, white or faint pink flowers with 5 petals, arranged in clusters of 5-20. Flower stalks are prickly, with robust stems (canes) that support large, flattened and hooked or straight prickles. Canes grow up to 3 metres in height and 12 metres in length at maturity. Evergreen leaves are predominantly large, rounded or oblong, and generally grouped in fives on first-year canes and threes on second year, flowering canes. Fruits are up to 2 cm in diameter, oblong to spherical, black, shiny and hairless. They form on second year canes and ripen from mid-summer to fall. Each berry produces numerous seeds that have a hard, impermeable coat.
Himalayan blackberry spreads by root and stem fragments, and birds and omnivorous mammals, such as foxes, bears, and coyotes consume berries and disperse seeds. Humans also contribute to blackberry spread by purposefully planting canes. Preferring rich, well-drained soil, blackberries can grow well in a variety of barren, infertile soil, and is tolerant of periodic flooding or shade. Thickets can produce 7,000-13,000 seeds per square meter, and seeds can remain viable in the soil for several years.
Himalayan blackberry out-competes low growing native vegetation through shading and build-up of leaf litter and dead stems. It can prevent the establishment of shade intolerant trees such as Garry Oak and ponderosa pine. Blackberries form large, dense, impenetrable thickets that can limit movement of large animals, take over stream channels and stream banks, and reduce sight lines along rights-of-ways. Thickets increase flooding and erosion potential by out-competing deep-rooted native shrubs that would otherwise provide bank stability.
Refer to Himalayan Blackberry T.I.P.S. for information on prevention and control methods.
Refer to Oregon State University's document, " Managing Himalayan Blackberry in western Oregon riparian areas " for information on management strategies, reproduction, distribution, herbicides, and biocontrol agents.