Koelreuteria elegans (Seem.) A.C.Sm., Sapindaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  High risk, score: 8 (Go to the risk assessment)

Common name(s): [more details]

Chinese: tai wan luan shu

English: Chinese rain tree, flame gold, golden rain tree

Fijian: lombolombo, manawi, tatange, towiwi, wiri, wiwi

Habit:  tree

Description:  "Tree 7-25 m in height, to ca. 50 cm (2 m recorded in Taiwan) in diameter; lenticels round to lens-shaped, pustulate, corky, cinnamon-brown; bark peeling in square plates, rough, somewhat corky, furrowed lengthwise. Leaves bipinnate, the odd terminal leaflet absent or much reduced, 25-60 cm long, 15-44 cm wide; rachis glabrous or short-hairy on the more or less grooved upper side; leaflets 8-17 on the major leaf divisions, strongly oblique, smooth and lustrous with barely manifest veins above, lanceolate to narrowly ovate to elliptic, 5.5-9.2 (-10.2) cm long, 1.3-3 (-4.2) cm wide, entire to irregularly crenate-serrate, long-acuminate to caudate at the thip, glabrous or with scattered straight hairs on the veins above and on petiolule, midvein beneath sparsely hairy with tufts of hairs in the axils and often with glands interspersed on the mid-vein and veinlets, sessile or with petiolules to ca 3 mm long. Inflorescence 30-50 cm long, 20-25 cm wide, densely puberulent and glandular, especially at anthesis, less so in fruit; flowers mildly sweet-fragrant; calyx lobes ciliate-glandular; pedicels scattered-puberulent or glabrous; petals usually 5 or 4, rarely 6, limb 5.5-7 mm long, 1.5-3.5 mm wide, acute or obtuse to rounded, appendages lobulate-undulate, claw 2-5 mm long, densely villous; stamens densely villous near base, 4.5-10.1 mm long. Capsules ellipsoidal, the valves rotund to suborbicular (placenta continuous and nonwinged), 3.4-5 (-6) cm long, (2.5-) 3.1-4.6 cm wide, inner side lustrous, reticulate-veined, scattered-pubescent when young, becoming glabrous, deep rose-purple while young, brownish at maturity; styles (1.5-) 2-6 mm long, seeds pyriform to nearly spherical, 5.2-5.5 mm in diameter, black, slightly rugose or smooth." (Meyer, 1976; pp. 156-164).

Habitat/ecology:  "Thrives in temperate climates. It tolerates full sun, partial shade, drought, frost, heat, well drained to wet soils, extended flooding and air pollution. It grows on a wide range of soil types and may be tolerant of light salt spray, but not of saline conditions"  (Australian Weed Management Guide).  Tolerates a range of soil types (Csurhes & Edwards, 1998; p. 114).

In Fiji, "occurs at elevations of 50-825 m in dense or open forest or on its edges, in dry secondary forest, in wooded gullies, and on dry hillsides, as an often spreading tree 4-25 m high" (Smith, 1985; pp. 612-613).

Propagation:  Seed (Csurhes & Edwards, 1998; p. 114).

Native range:  Taiwan, Fiji.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Fiji Fiji Islands	Vanua Levu Island	native	Smith, Albert C. (1985) (pp. 612-613) Vouchers cited: Berry 24, Smith 6429, DA 14327
Fiji Fiji Islands	Viti Levu Island	native	Smith, Albert C. (1985) (pp. 612-613) Vouchers cited: Greenwood 450, DA 14778, DA 2359, DA 14725, Parks 20795, Gillespie 4181, Vaughan 3437, DF 1185, DF 1171, DF 1191, H.B.R. Parham 283a/b, H.B.R. Parham 301, W.L. Parham 4, Degener 15435, DA 1213
Guam Guam Island	Guam Island	introduced invasive	Fosberg, F. R./Falanruw, M. V. C. (1980) (p. 206) Koelreuteria formosana Hayata (Koelreuteria elegans ssp. formosana (Hayata) Meyer); voucher cited Fosberg 58342 (US)
State of Hawaii Hawaiian Islands	Hawaiian Islands	introduced cultivated	Staples, George W./Herbst, Derral/Imada, Clyde T. (2000) (p. 29)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Oppenheimer, Hank L. (2003) (p. 25) Subsp. formosana (Hayata) F.G. Mey. West Maui. Voucher cited: Oppenheimer H10141 (BISH, PTBG)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (p. 48) East Maui. Vouchers cited: Starr & Starr 060814-01 (BISH), Starr & Starr 060814-03 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Frohlich, Danielle/Lau, Alex (2010) (p. 16) subsp. formosana (Hayata) F.G. Mey. Voucher cited: D. Frohlich & A. Lau 2008041101(BISH)
Japan (offshore islands) Bonin (Ogasawara) Islands	Bonin (Ogasawara) Islands	introduced	Kato, Hidetoshi (2007) As Koelreuteria henryi Dummer [Koelreuteria elegans (Seem.) A.C.Sm. subsp. formosana (Hayata) F.G.Mey.]
Philippines Philippine Islands	Philippine Islands	native	Merrill, Elmer D. (1925) (p. 235) In thickets along streams at low and medium altitudes.

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 cultivated	Csurhes, S./Edwards, R. (1998) (p. 114)
Australia Australia (continental)	Queensland	introduced invasive	Queensland Herbarium (2002) (p. 4)
Taiwan Taiwan	Taiwan Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Taiwan Taiwan	Taiwan Island	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2011) subsp. formosana (Hayata) F. G. Meyer

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	USA (Florida)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

Comments:  "Listed by the Brisbane City Council as a weed of bushland around Brisbane" (Csurhes & Edwards, 1998; p. 114). "In Florida it has escaped from cultivation in certain areas" (Meyer, 1976; pp. 156-164).

Additional information:
Weed Management Guide from the Government of Australia. (PDF format).

Additional online information about Koelreuteria elegans is available from the Hawaiian Ecosystems at Risk project (HEAR).

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

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

References:

Csurhes, S./Edwards, R. 1998. Potential environmental weeds in Australia: Candidate species for preventative control. Canberra, Australia. Biodiversity Group, Environment Australia. 208 pp.

Fosberg, F. R./Falanruw, M. V. C. 1980. Noteworthy Micronesian plants 4. Micronesica 16(2):201-210.

Frohlich, Danielle/Lau, Alex. 2010. New plant records from O‘ahu for 2008. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2008. Bishop Museum Occasional Papers 107:3-18.

Kato, Hidetoshi. 2007. Herbarium records of Makino Herbarium, Tokyo Metropolitan University. Personal communication.

Merrill, Elmer D. 1925. An enumeration of Philippine flowering plants, vol. 1 [reprint]. Bureau of Printing, Manila. 463 pp.

Meyer, F. G. 1976. A revision of the genus Koelreuteria (Sapindaceae). J. Arnold Arbor. 57(2): 156-164.

Oppenheimer, Hank L. 2003. New plant records from Maui and Hawai‘i Counties. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2001-2002. Part 1: Articles. Bishop Museum Occasional Papers. 73:3-30.

Queensland Herbarium. 2002. Invasive Naturalised Plants in Southeast Queensland, alphabetical by genus. Modified from: Batianoff, George N. and Butler, Don W. (2002). Assessment of Invasive naturalized plants in south-east Queensland. Appendix. Plant Protection Quarterly 17, 27-34. 11 pp.

Smith, Albert C. 1985. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 3. 758 pp.

Staples, George W./Herbst, Derral/Imada, Clyde T. 2000. Survey of invasive or potentially invasive cultivated plants in Hawai‘i. Bishop Museum Occasional Papers No. 65. 35 pp.

Starr, Forest/Starr, Kim/Loope, Lloyd. 2008. New plant records from the Hawaiian Archipelago. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2007. Bishop Museum Occasional Papers 100:44-49.

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

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

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