Rhododendron indicum (Linnaeus) Sweet, Ericaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Evaluate, score: 4 (Go to the risk assessment)

Other Latin names:  Azalea indica L.

Common name(s): [more details]

Chinese: gao yue du juan

Habit:  shrub

Description:  "Much-branched shrub, usually low and prostrate, though sometimes up to 2 m; young shoots covered with adpressed flattened chestnut-brown setose hairs.  Leaves dimorphic, chartaceous; spring leaves narrowly lanceolate to oblanceolate, 2-3 x 0.8 -1 cm, 2.3-3 x as long as broad, apex acute, base cuneate, margin remotely crenate-serrulate, ciliate, upper surface with scattered bristles, lower surface paler, with setose bristles restricted to midrib; summer leaves 10-18 x 3-5 mm, otherwise as for spring leaves; petioles 2-4 mm, clothed with adpressed chestnut-brown setose hairs.  Inflorescence 1-2-flowered; pedicels 5-10 mm, clothed with brown strigose hairs.  Calyx with brown strigose hairs, especially on lobe margins, lobes ovate to orbicular, c. 1 mm long.  Corolla broadly funnel-shaped, bright red to scarlet, occasionally rose-red, 30-50 mm; tube half the length of corolla, glabrous.  Stamens 5, as long as or slightly exceeding the corolla, filaments scabrid below.  Ovary densely covered with adpressed shining brown hairs; style glabrous.  Capsule oblong-ovoid, c. 10 mm long, densely strigose" (Chamberlain & Rae, 1990; pp. 119-120).

Habitat/ecology:  In Japan, "wooded river banks, etc.; also widely cultivated and sometimes escaping" (Chamberlain & Rae, 1990; pp. 119-120).

Propagation:  Seed

Native range:  Japan (S. and W. Honshu, Kyushyu) (Chamberlain & Rae, 1990; pp. 119-120).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Nauru Nauru Island	Nauru Island	introduced cultivated	Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. (1994) (p. 125) Rhododendron sp., rare, planted ornamental.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
China China	China (People's Republic of)	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2011) Widely cultivated in China.
Japan Japan	Japan (country)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Singapore Singapore	Singapore (Republic of)	introduced cultivated	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 75) Cultivated only

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Indian Ocean offshore islands) Christmas Island Group	Christmas Island	introduced cultivated	Swarbrick, J. T. (1997) (p. 125)

Additional information:
Additional online information about Rhododendron indicum is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Rhododendron indicum as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Rhododendron indicum may be available from the Germplasm Resources Information Network (GRIN).

References:

Chamberlain, D. F./S. J. Rae, S. J. 1990. A revision of Rhododendron. IV. Subgenus Tsutsusi. Edinburgh J. Bot. 47.

Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species. Raffles Museum of Biodiversity Research, National University of Singapore. 273 pp.

Swarbrick, J. T. 1997. Environmental weeds and exotic plants on Christmas Island, Indian Ocean: a report to Parks Australia. 101 pp. plus appendix.

Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. 1994. The flora of Nauru. Smithsonian Institution, Washington. Atoll Research Bulletin 392:1-223.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2011. Flora of China (online resource).