Rhodomyrtus tomentosa (Aiton) Hassk., Myrtaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

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

Common name(s): [more details]

English: downy myrtle, downy rose myrtle, Isenberg bush, rhodomyrtus, rose myrtle

French: feijoa, feijoarte-groseille, myrte-groseille

Spanish: guayabillo forastero

Habit:  shrub

Description:  "A large shrub to small twiggy tree, up to 10 feet high; older branches yellowish, fissured with loose bark. Leaves 2 to 3 inches long, 3-veined from the base, oval, obtuse to sharp pointed at the tip, densely gray or rarely yellowish-hairy beneath, entire, with wide leafstalk. Flowers 3/4 to 1 inch wide, solitary or two to three; petals tinged white outside with purplish-pink or all pink. Fruit purple, round, 3-celled, capped with persistent calyx lobes, about 1/2 inch wide, soft with double row of seeds in each cell, edible. Seeds triangular" (Haselwood, 1966; p. 282).

Habitat/ecology:  This noxious evergreen shrub rarely grows above 3 m but forms dense thickets (Smith, 1985; p. 201). "Thrives in environments where annual rainfall exceeds 1200 mm.  A weed of pasture, rangeland and untended  areas. Forms impenetrable thickets" (Waterhouse & Mitchell, 1998; pp. 55-56).

Moist and wet forests, bog margins, up to 3000 ft. elevation in Hawai‘i.

Propagation:  Produces large amounts of seed that are dispersed by frugivorous birds.

Native range:  Southeast Asia, Malaysia, and the Philippines.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
French Polynesia Society Islands	Raiatea (Havai) Island	introduced invasive	Meyer, Jean-Yves (2000) (p. 93) Mesic/wet habitats.
French Polynesia Society Islands	Raiatea (Havai) Island	possibly introduced	Welsh, S. L. (1998) (p. 201) Vouchers cited: Whistler 4884, BRY 24865, BRY 26622
French Polynesia Society Islands	Raiatea (Havai) Island		Bishop Museum (Honolulu) (1990) (voucher ID: BISH 642901) Taxon name on voucher: Rhodomyrtus tomentosa (Aiton) Hassk.
French Polynesia Society Islands	Raiatea (Havai) Island		Bishop Museum (Honolulu) (1993) (voucher ID: BISH 658360) Taxon name on voucher: Rhodomyrtus tomentosa (Aiton) Hassk.
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 972-973)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 972-973)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive cultivated	Staples, George W./Imada, Clyde T./Herbst, Derral R. (2002) (p. 13) Voucher cited: O. & I. Degener 28503 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 972-973)
Japan (offshore islands) Bonin (Ogasawara) Islands	Bonin (Ogasawara) Islands	introduced	Kato, Hidetoshi (2007)
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Cambodia Cambodia	Cambodia (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Taiwan Taiwan	Taiwan Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)

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. (2005)

Comments:  On the State of Hawai‘i noxious weed list. A serious problem on Raiatea, French Polynesia (Meyer, 1998).

Control: 

Physical:  Hand pull or dig out seedlings and young plants. "Not grazed by cattle"  (Motooka et al., 2003).

Chemical:  Cut large plants and treat the stumps with herbicide.  "Sensitive to foliar applications of dicamba at 2 lb/acre and triclopyr at 2 lb/acre but requires follow-up treatments.  Sensitive to conventional basal bark applications of 2% triclopyr ester product and to 20% in very-low-volume basal bark applications.  In stump bark applications, 2% 2,4-D or triclopyr ester products in oil by conventional spraying or 20% triclopyr ester product in very-low-volume applications were effective.  Tolerates metsulfuron and soil-applied tebuthiuron"  (Motooka et al., 2003).

Additional information:  Report (PDF format) from US Geological Survey, Biological Resources Division, Haleakala Field Station, Hawaii "Plants of Hawaii".
Information from the book "Weeds of Hawaii‘s Pastures and Natural Areas; An Identification and Management Guide" (Motooka et al., 2003). (PDF format).
Information from the World Agroforestry Centre's AgroForestryTree Database.

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

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

References:

Bishop Museum (Honolulu). 1990. Voucher specimen #BISH 642901 (Florence 10448).

Bishop Museum (Honolulu). 1993. Voucher specimen #BISH 658360 (Florence 11903).

Haselwood, E. L./Motter, G. G. 1983. Handbook of Hawaiian Weeds. Second edition, revised and expanded by Robert T. Hirano. University of Hawaii Press. 491 pp.

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

Meyer, Jean-Yves. 1998. Mécanismes et gestion des invasions biologiques par des plantes introduites dans des forêts naturales à Hawai‘i et Polynésie Française: une étude de cas [Mechanisms and management of biological invasions by alien plants in Hawaiian and French Polynesian natural forests: a case study]. Dèlégation à la Recherche, B.P. 20981 Papeete, Tahiti, Polynésie Française. Unpublished report.

Meyer, Jean-Yves. 2000. Preliminary review of the invasive plants in the Pacific islands (SPREP Member Countries). In: Sherley, G. (tech. ed.). Invasive species in the Pacific: A technical review and draft regional strategy. South Pacific Regional Environment Programme, Samoa. 190 pp.

Motooka, Philip/Castro, Luisa/Nelson, Duane/ Nagai, Guy/Ching, Lincoln. 2003. Weeds of Hawaii‘s Pastures and Natural Areas; An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. 184 pp.

Smith, Clifford W. 1985. Impact of Alien Plants on Hawai‘i's Native Biota. In: Stone, Charles P. and Scott, J. Michael, eds. Hawai‘i's terrestrial ecosystems: preservation and Management. Cooperative National Park Resources Studies Unit, University of Hawaii, Manoa.

Staples, George W./Imada, Clyde T./Herbst, Derral R. 2002. New Hawaiian plant records for 2000. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2000. Part 1: Articles. Bishop Museum Occasional Papers. 68:3-18.

U.S. Dept. Agr., Agr. Res. Serv. 2007. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2005. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Waterhouse, B. M./Mitchell, A. A. 1998. Northern Australia Quarantine Strategy: weeds target list. Second edition. Australian Quarantine & Inspection Service, Miscellaneous Publication No. 6/98. 110 pp.

Welsh, S. L. 1998. Flora Societensis: A summary revision of the flowering plants of the Society Islands. E.P.S. Inc., Orem, Utah. 420 pp.