Rhododendron indicum (Linnaeus) Sweet, Ericaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

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

Other Latin names:  Azalea indica L.

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
Japan Japan	Japan (country)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)

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).

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.

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. 2007. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.