Rubus discolor Weihe & Nees, Rosaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  High risk, score: 24 (Go to the risk assessment)

Other Latin names:  Rubus armeniacus Focke

Common name(s): [more details]

English: Himalaya blackberry

Habit:  shrub

Description:  "A robust, sprawling, more or less evergreen, glandless shrub.  The shrubs appear as "great mounds or banks" (Bailey, 1945), with some of the canes standing up to 3 m tall.  Other canes are decumbent, trailing or scandent up to 20-40 feet long (Bailey, 1923), frequently taking root at the tips.  The pimocanes are pilose-pubescent, becoming nearly glabrous with age.  These are strongly angled and furrowed, bearing well-spaced, heavy, broad-based, straight or somewhat curved prickles 6-10 mm long.  Pimocane leaves are 5-foliate, glabrous above when mature and cano-pubescent to cano-tomentose beneath.  There are hooked prickles on the petioles and petiolules.  The leaflets are large and broad with the terminal leaflet roundish to broad oblong.  Leaflets are abruptly narrowed at the apex, unequally and coarsely serrate-dentate.  Floricane leaflets are 3-5 foliate and smaller than on the pimocanes.  The inflorescence is a large terminal cluster with branches in the lower axils.  The peduncles and pedicels are cano-tomentose and prickly.  The flowers are white or rose colored, 2-2.5 cm across, with broad petals.  Sepals are broad, cano-tomentose, conspicuously pointed and soon reflexed, approximately 7-8 mm long.  The roundish fruit is black and shiny, up to 2 cm long, with large succulent drupelets"  (Starr, Starr & Loope, 2003; p. 2).

Habitat/ecology:  "Himalayan blackberry grows in vacant lots, logging sites, burned areas, along rivers, roads, fences, and railroad tracks. It grows best in full sunlight but does well under a light forest cover. However, it will not grow under a dense canopy. Himalayan blackberry colonizes most soil types in moist areas but is confined to riparian areas and the edges of irrigated fields in interior dry climates. It grows at elevations from near sea level on the West Coast to 1,500 m in the inland West (Welsh and others 1987). Himalayan blackberry is confined at the northern extent of its range to mild coastal areas and low-elevation, sheltered inland sites. It tolerates periodic flooding of fresh or even brackish water. The species vigorously sprouts from root systems after fires (Tirmenstein 1989)"  (Wildland shrubs of the United States and its territories).  "Wastelands, pastures, forest plantations, along roads, creek gullies, river flats and fence lines"  (Starr, Starr & Loope, 2003; p. 2).

Propagation:  Seed and cuttings. Canes root at tips (Starr, Starr & Loope, 2003; pp. 2-3).  "The seeds are dispersed by birds and mammals as well as by gravity. Once seedlings become established, most subsequent reproduction is vegetative. Plants reproduce by sprouts from rhizomes and by layering (rooting) at the nodes when stems come in contact with the ground"  (Wildland shrubs of the United States and its territories).

Native range:  Western Europe (Starr, Starr & Loope, 2003; pp. 3).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Maui Island	introduced cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1106) West Maui. Voucher cited: Krauss 1136 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Starr, Kim (2011) (p. 32) East Maui. Voucher cited: Starr & Starr 051123-01 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1106)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Conant, Patrick (1996) (p. 2) Voucher cited: P. Conant & L. Nagasawa s.n. (BISH)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Queensland	introduced invasive	Queensland Herbarium (2002) (p. 7)

Control:  Management information on the Global Invasive Species Database.
Additional control information from the Bugwood Wiki.

Physical: "Mechanical control of this species is tough due to sharp prickles and large thickets. It may be possible to pull or dig up small seedlings. The entire plant, above and below ground, must be carefully removed to prevent re-growth. Plants are sometimes cut back to reduce biomass before chemical control is done"  (P. Bily pers. comm.)".  "Plants can be eliminated by grubbing with follow-up treatment a year later, repeated mowing, and by pasturing with goats (Cox 2003). Because of dormant seeds in the soil, checking and retreatment for many years may be required to completely eliminate the species"  (Wildland shrubs of the United States and its territories).

Chemical: "Various forms of chemical methods can be used to control Rubus discolor, including foliar, stem injection, cut stump and basal stem methods using glyphosate or triclopyr products. Plants on East Maui [Hawaii] have been treated with a 10% Garlon 4 in oil basal stem method (P. Bily pers. comm.)".

Biological: "Several biological control agents have been introduced to Hawai‘i for the related species, Rubus argutus (prickly Florida blackberry). None are known for Rubus discolor" (Starr, Starr & Loope, 2003; p. 4).