Rubus armeniacus

An example of the drupes, showing both unripe (green then red) and two ripe drupes.

The species was introduced to Europe in 1835 and to Australia and North America in 1885. It was valued for its fruit, similar to that of common blackberries (Rubus fruticosus and allies) but larger and sweeter, making it a more attractive species for both domestic and commercial fruit production. The immature fruits are smaller, red, and hard with a much more sour taste. The cultivars Himalayan Giant and Theodore Reimers are commonly planted.[3][4] Rubus armeniacus was used in the cultivation of the Marionberry cultivar of blackberry.[9]

When established for several years, if left alone Rubus armeniacus can grow into a large cluster of canes. These thickets can provide good nesting grounds for birds, and help to provide places to rest/hide for other slightly larger mammals, such as rabbits, squirrels, and beavers.[10] While areas with Rubus A. provide good sources for bird nests, birds do prefer areas with more natural/native plants when given the option.[11]

Rubus armeniacus was first introduced to North America in 1885 by Luther Burbank in Santa Rosa, California using seeds that he imported from India.[12][13] The species thrived in its new environment, notably for the large amount of berries it produced and was soon grown and cultivated in the United States by 1915.[14] It soon escaped from cultivation and has become an invasive species in most of the temperate world and the United States Pacific Coast by 1945.[15][3][4][16][9][17] Because it is so hard to contain, it quickly gets out of control, with birds and other animals eating the fruit and then spreading the seeds.[18] It is highly flammable and a common ladder fuel for wildfires,[19] due to the litter and dead canes produced by the plant.[20][21]

R. armeniacus bush covering a field in Germany.

It is especially established west of the Cascades in the American Pacific Northwest[10] and in parts of southern British Columbia along the coast, in the Lower Mainland, and throughout Vancouver Island.[22] It does well in riparian zones due to the abundance of other species in these areas, which allows it to go relatively unnoticed until it has had a chance to establish itself.[9] Unlike other invasive species, this plant can easily establish itself and continue to spread in ecosystems that have not experienced a disturbance.[10]

The plant itself develops large root systems, allowing it to find water from other sources than just the immediate area. It can also hold onto water in its canes, allowing it to thrive more than other plants during dry seasons or droughts.[23]Himalayan blackberries grow very well in sandy, well draining soil with a lot of natural light, even if there is not a lot of soil nutrients.[24] All of the Himalayan blackberry’s adaptations to grow in these conditions continue to make it a difficult plant to remove and an invasive species. Rubus A. is able to survive during drought periods because of their extensive root systems. Not only are their roots spread out over a wide area, they also can go very deep underground, allowing them to reach water most smaller plants and shrubs wouldn’t reach.[24] They also store more water in their canes that act like a water reservoir.[25] This added water also allows them to release oxygen and take in more CO2 without fearing major losses of water. Since they store water in their canes and roots, they have excess water ready for use or for loss when opening their stomata.[25]

Cutting the canes to the ground, or burning thickets of Rubus armeniacus are ineffective removal strategies. The best practices for removal include digging up the rhizomes and connecting underground structures, and herbicides.[9] Broken roots can resprout, making manual removal extra labor intensive, and glyphosate herbicides are largely ineffective with this plant.