Rubus armeniacus

Rubus armeniacus is a perennial plant that bears biennial stems ("canes") from the perennial root system. In its first year a new stem grows vigorously to its full length of 4–10 m, trailing along the ground or arching up to 4 m high. The stem is stout, up to diameter at the base, and green; it is polygonal (usually hexagonal) in cross-section, with fearsome thorns up to 1.5 cm long forming along the ribs. The canes can turn more red/purple if they are exposed to bright sunlight. This is common in the summer. The leaves on first-year shoots are 7–20 cm long, palmately compound with either three or more commonly five leaflets. The leaflets are moderately serrated. Flowers are not produced on first-year shoots. In its second year, the stem does not grow longer, but produces several side shoots, which bear smaller leaves with three leaflets (rarely a single leaflet). These leaflets are oval-acute, dark green above and pale to whitish below, with a toothed margin, and snaring, hooked thorns along the midrib on the underside. The flowers are produced in late spring and early summer on panicles of 3–20 together on the tips of the second-year side shoots, each flower 2–2.5 cm diameter with five white or pale pink petals. The flowers are bisexual (perfect) containing both male and female reproductive structures. The fruit in botanical terminology is not a berry, but an aggregate fruit of numerous drupelets, 1.2–2 cm diameter, ripening black or dark purple. Both first- and second-year shoots are spiny, with short, stout, curved, sharp spines. Mature plants form a tangle of dense arching stems, the branches rooting from the node tip when they reach the ground. The fleshy growing cane tips contain the antifeedant compounds, 2-heptanol and methyl salicylate at higher concentrations than mature leaves. At the concentration found in the growing cane tips, 2-heptanol is a banana slug (Ariolimax columbianus) antifeedant. The lack of phytophagous insects observed on the growing cane tips is likely due to the presence of methyl salicylate. This compound is a known aphid repellant and has been shown to attract predators in response to insect herbivory. ==Taxonomy==

Both the scientific name and the species' origin have been the subject of much confusion, with much of the literature referring to it as either Rubus procerus or Rubus discolor, and often mistakenly citing its origin as western European. Flora of North America, published in 2014, considers the taxonomy unsettled, and tentatively uses the older name Rubus bifrons. ==As an invasive species==

Spread Luther Burbank, who popularized the misleading name "Himalayan", introduced Rubus armeniacus to North America in 1885 in Santa Rosa, California, using seeds that he imported from India. The species thrived in its new environment, notably for the large amount of berries it produced. By 1915, it was widely grown and cultivated in the United States. It soon escaped from cultivation, and became an invasive species in most of the temperate world and the U.S. Pacific Coast by 1945. It is listed as an invasive species in the U.S. State of Missouri and prohibited in the U.S. state of Wisconsin. 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. It is highly flammable and a common ladder fuel for wildfires, due to the litter and dead canes produced by the plant. It is especially established west of the Cascades in the American Pacific Northwest and in parts of southern British Columbia along the coast, in the Lower Mainland, and throughout Vancouver Island. 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. Himalayan blackberries grow very well in sandy, well-drained soil with a lot of natural light, even if the soil is lacking in nutrients. 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. R. armeniacus 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 would not reach. ==Cultivation==

Berry crop The species was introduced to Europe in 1835 and to Australia and North America in 1885. It was valued for its edible fruit, similar to that of common blackberries (e.g. Rubus fruticosus) 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. ==See also==