Grevillea robusta A.Cunn. ex R.Br., Proteaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Risk assessment results:  Evaluate, score: 5 (Go to the risk assessment)

Common name(s): [more details]

English: he oak, she-oak, silk oak, silky oak, silver oak

French: chêne d'Australie

Hawaiian: ha‘iku ke‘oke‘o

Tongan: ‘oka kilika, oke‘

Habit:  tree

Description:  "Large evergreen tree 18-30 m high with a straight trunk and moderately spreading crown.  Leaves:  Dark green above, grayish-white or rusty-silky beneath, two-pinnatifid, deeply incised, fern-like, 150-300 mm long, leaflet margins recurved.  Flowers:  Golden-orange, stalked, 20-30 mm long, in terminal, bottlebrush-like sprays 80-150 mm long.  Fruits: Brownish-black, leathery follicles about 20 mm long, containing one or two flat, winged seeds"  (Henderson, 1995; p. 82).

Habitat/ecology:  This large, evergreen tree has been used extensively in reforestation programs. The leaves produce an allelopathic substance that inhibits the establishment of all species, including itself apparently.  It grows well in dry areas between 350-1,600 m (Smith, 1985; p. 191). "Widely planted and a prolific seeder, it is a weed of drier mesic pastures and forests.  Pollen may trigger hay fever"  (Motooka et al., 2003).  In New Caledonia, "arbre planté assez commun à Nouméa et dans l'intérieur" (MacKee, 1994; p. 119).

Propagation:  Wind-dispersed seeds.

Native range:  Eastern Australia

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced	Pickard, J. (1984) (p. 207)
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 20) "Frequently planted as a timber tree throughout tropical and subtropical regions, and often becoming naturalised". Voucher cited: A.C. Beauglehole 5509 (MEL)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 10) "Frequently planted as a timber tree throughout tropical and subtropical regions, and often becoming naturalised". Voucher cited: W.R. Sykes NI 514 (CHR)
Cook Islands Southern Cook Islands	‘Atiu Island	cultivated	McCormack, Gerald (2007) Uncommon.
Cook Islands Southern Cook Islands	Mangaia Island	cultivated	McCormack, Gerald (2007) Uncommon.
Ecuador (Galápagos Islands) San Cristóbal Group	San Cristóbal Island	introduced cultivated	Charles Darwin Research Station (2005)
French Polynesia Society Islands	Raiatea (Havai) Island	introduced	Fosberg, F. R. (1997) (p. 126)
French Polynesia Society Islands	Taha‘a Island	introduced	Fosberg, F. R. (1997) (p. 126)
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Welsh, S. L. (1998) (p. 224) Voucher cited: Florence 2448
French Polynesia Tubuai (Austral) Islands	Rurutu Island		? (year unknown)
Guam Guam Island	Guam Island	introduced cultivated	Stone, Benjamin C. (1970) (pp. 259-260) Voucher cited: Stone 4092 (GUAM)
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 63)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1086)
State of Hawaii Hawaiian Islands	Kaho‘olawe Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2006) (p. 40) Single seedling seen and pulled. Voucher cited: Starr, Starr, Higashino & Bruch 040607-1 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1086)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive cultivated	Herbarium Pacificum Staff (1999) (p. 8) Voucher cited: C. Imada, H. Oppenheimer, J.S. Meidell & C. Gemmill 98-7 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1086)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive cultivated	Oppenheimer, Hank L. (2003) (p. 22) Voucher cited: Oppenheimer H110129 (BISH, PTBG)
State of Hawaii Hawaiian Islands	Ni‘ihau Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1086)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1086)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced cultivated	MacKee, H. S. (1994) (p. 119) Vouchers cited: Cribs 1300, Le Rat 222, Sarlin 57, MacKee 29471
Niue Niue	Niue Island	introduced cultivated	Sykes, W. R. (1970) (p. 172) Single tree. Voucher cited: CHR 168710
Niue Niue	Niue Island	introduced cultivated	Space, James C./Flynn, Tim (2000) (p. 24)
Samoa Western Samoa Islands	Upolu Island	introduced cultivated	Space, James C./Flynn, Tim (2002) (p. 9) Planted tree at watershed nursery, Vailima.
Solomon Islands Solomon Islands	Solomon Islands	introduced cultivated	Hancock, I. R./Henderson, C. P. (1988) (p. 79)
Tonga Tongatapu Group	‘Eua Island	introduced cultivated	Space, James C./Flynn, Tim (2001) (p. 7)
Tonga Tongatapu Group	Tongatapu Island	introduced cultivated	Space, James C./Flynn, Tim (2001) (p. 7)
Tonga Vava‘u Group	Vava‘u Island	introduced cultivated	Space, James C./Flynn, Tim (2001) (p. 7)

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)	New South Wales	native	Australian Biological Resources Study (2007)
Australia Australia (continental)	Queensland	native	Australian Biological Resources Study (2007)
New Zealand New Zealand	New Zealand (country)	introduced invasive cultivated	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 997) "Rough pasture on scoria of volcanic cone".

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. 115)

Comments:  This tree is sometimes used in forestry plantings. It is naturalized in Hawai‘i. Where not present, it should probably not be introduced. New plantings should be limited and existing plantings monitored for invasive behavior.

Naturalized and starting to spread on the island of Rurutu (Austral archipelago, French Polynesia) (Jean-Yves Meyer, pers. com.).

Single tree noted at the watershed nursery in Vailima, Upolu, Samoa (Space & Flynn, 2002).

Control: 

Physical: "Has value as timber. Goats will control silver oak (An Peischel)" (Motooka et al., 2003).

Chemical: "Sensitive to triclopyr ester (2.5% product in diesel oil) applied to frill cuts.  HAVO staff reported control with triclopyr ester at 5% product in diesel oil applied to basal bark (Zimmer, HAVO).  Susceptible to cut-surface and continuous frill applications of picloram and glyphosate and tolerant of 2,4-D and dicamba. Applications of glyphosate and triclopyr to drilled holes in unreplicated demonstrations were very effective" (Motooka et al., 2003).

Additional information:  Information from the book "Weeds of Hawaii‘s Pastures and Natural Areas; An Identification and Management Guide" (Motooka et al., 2003). (PDF format).
Information on this species from "Silvics of North American", USDA Agriculture Handbook 654.
Fact sheet from "Common forest trees of Hawaii" (PDF format).
Information from the World Agroforestry Centre's AgroForestryTree Database.

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

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

References:

Australian Biological Resources Study. 2007. Flora of Australia Online. Australian Biological Resources Study, Canberra.

Charles Darwin Research Station. 2005. CDRS Herbarium records.

Fosberg, F. R. 1997. Preliminary checklist of the flowering plants and ferns of the Society Islands. Ed. by David R. Stoddart. U. Cal. Berkeley.

Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce. 1979. A geographical checklist of the Micronesian dicotyledonae. Micronesica 15:1-295.

Hancock, I. R./Henderson, C. P. 1988. Flora of the Solomon Islands. Research Bulletin No. 7. Ministry of Agriculture and Lands, Honiara. 203 pp.

Henderson, Lesley. 1995. Plant invaders of Southern Africa. Plant Protection Research Institute Handbook No. 5, Agriculture Research Council, ARC/LNR, Pretoria, South Africa. 177 pp.

Herbarium Pacificum Staff. 1999. New Hawaiian plant records for 1998. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 1998. Part 1: Articles. Bishop Museum Occasional Papers. 58:3-11.

Little, Elbert L./Skolmen, Roger G. 1989. Common forest trees of Hawaii (native and introduced). USDA Agriculture Handbook 679. Washington, D.C. 377 pp. + plates.

MacKee, H. S. 1994. Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie. Muséum National d'Histoire Naturelle, Paris, 164 p.

McCormack, Gerald. 2007. Cook Islands biodiversity and natural heritage. On-line database.

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.

Motooka, Philip/Ching, Lincoln/Nagai, Guy. 2002. Herbicidal Weed Control Methods for Pasture and Natural Areas of Hawaii. Cooperative Extension Service, College of Tropical Agriculture and Human Resources, University of Hawai‘i. CTAHR free publication WC-8.

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.

Orchard, Anthony E., ed. 1994. Flora of Australia. Vol. 49, Oceanic islands 1. Australian Government Publishing Service, Canberra.

Pickard, J. 1984. Exotic plants on Lord Howe Island: Distribution in space and time, 1853-1981. J. of Biogeography 11:181-208.

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.

Space, James C./Flynn, Tim. 2000. Report to the Government of Niue on invasive plant species of environmental concern.  USDA Forest Service, Honolulu. 34 pp.

Space, James C./Flynn, Tim. 2001. Report to the Kingdom of Tonga on invasive plant species of environmental concern.  USDA Forest Service, Honolulu. 78 pp.

Space, James C./Flynn, Tim. 2002. Report to the Government of Samoa on invasive plant species of environmental concern. USDA Forest Service, Honolulu. 83 pp.

Starr, Forest/Starr, Kim/Loope, Lloyd L. 2006. New plant records from the Hawaiian Archipelago. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2004-2005. Part 1: Articles. Bishop Museum Occasional Papers 87:31-43.

Stone, Benjamin C. 1970. The flora of Guam. Micronesica 6:1-659.

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

Sykes, W. R. 1970. Contributions to the flora of Niue. New Zealand Department of Scientific and Industrial Research Bulletin 200, Wellington. 321 pp.

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

Virot, Robert. 1968. Protéacées. Flore de la Nouvelle-Calédonie et Dépendances. Muséum National d'Histoire Naturelle, Paris. Vol. 2, 254 pp.

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).

Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. 1988. Flora of New Zealand, Volume IV: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 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.