Gaire, R., Astley, C., Upadhyaya, M. K., Clements, D. R. and Bargen, M. 2015. The Biology of Canadian Weeds. 154. Himalayan blackberry. Can. J. Plant Sci. 95: 557-570. Himalayan blackberry, an invasive weed in Canada, is particularly problematic in southwestern British Columbia. Isolated occurrences have also been recorded in Ontario. The nomenclature of this species has been under review recently; Rubus armeniacus Focke, R. discolor Weihe & Nees, and R. bifrons Vest have been frequently applied, as well as R. procerus auct. Non P. Muell. Ex Genev, Rubus praecox Bertol., R. vestitus Weihe and others. Himalayan blackberry microspecies in North America are within the species aggregate R. fruticosus L. Because the Canadian material has yet to be analysed genetically we refer to the species by the common name Himalayan blackberry in this account. Because of its vigorous growth in temperate, moist environments, it has become a problem weed in the Pacific Northwest, where it outcompetes native plant species by shading. It reproduces by seeds and vegetatively, forming dense thickets. Although humans value blackberries harvested from Himalayan blackberry and the plant also provides habitat and food for wildlife, management to prevent excessive growth is recommended. Nesting songbirds preferred more diverse, “natural” forest types over Himalayan blackberry-dominated thickets in southwestern British Columbia. Chopping, cutting, mowing or browsing by goats and/or herbicide application are effective management strategies but require diligence to prevent vegetative re-growth. A leaf fungal rust, Phragmidium violaceum (Schultz) Winter, has recently become a major pathogen of Himalayan blackberry in Oregon, and was found to occur in British Columbia in 2008.