Olea europaea L., Oleaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Evaluate, score: 2 (Go to the risk assessment (Australia))
ssp. cuspidata: High risk, score: 11 (Go to the risk assessment (Pacific))
ssp. europaea: Evaluate, score: 3 (Go to the risk assessment (Pacific))

Common name(s): [more details]

Chinese: mu xi lan

English: olive

Hawaiian: ‘oliwa, ‘oliwa haole

Spanish: oliva

Tahitian: orive

Habit:  tree

Description:  "Trees to 8-10 m tall with a broad crown, sometimes shrubby; young branches grayish lepidote. Leaves narrowly elliptic to oblong or lanceolate, (1-) 2-8 cm long, (0.3-) 0.5-1.5 (-2) cm wide, upper surface glabrous, lower surface moderately to densely grayish, green, or golden lepidote.  Flowers in axillary, decussate panicles shorter than the leaves; corolla white, ca. 3.5-4 mm long. Drupes green when immature, becoming black or brownish at maturity, subglobose to narrowly ellipsoid, 6-19 mm long." 

Subspecies europaea:  "Lower leaf surface densely grayish lepidote and thick, fleshy fruit 15-19 mm long".

Subspecies cuspidata:  "Lower leaf surface moderately to densely green or golden lepidote and thinly fleshy fruit ca. 6-7 mm long" (Wagner et al., 1999; p. 992).

Habitat/ecology:  "Grass- and woodland, riparian habitats.  Where native, this tree grows in woods, scrub, and dry rocky places up to 3000 m elevation.  The growth form ranges from stunted shrubs to tall trees.  The domestic olive is a group of more than 2500 cultivars.  Naturalized plants belon to var. africana.  Where invasive, the tree forms a dense and permanent canopy under which native shrubs and trees cannot grow, but seedlings of this tree grow well.  Over time, it transforms native vegetation into a species-poor shrubland"  (Weber, 2003; p. 287).  "Growth is most prolific in semi-arid to sub-humid warm-temperate regions, usually with winter-dominant rainfall and hot, relatively dry summers, on a range of soils (Parsons & Cuthbertson, 1992, cited in Csurhes & Edwards, 1998; p. 120).  "Forms dense canopies that shade out the understory"  (Motooka et al., 2003).

Propagation:  Seed, spread by birds and animals. A prolific seed producer.

Native range:  Mediterranean region, widely cultivated.

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) subsp. africana
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island		Ziesing, P. (1997) (pp. 24-25)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 10) Subsp. cuspidata (Wall. ex G.Don) Cif. "Naturalised and invasive in the National Park and other areas of native vegetation". Vouchers cited: R.D. Hoogland 6635 (CANB); R.D. Hoogland 11328 (CANB, NSW); G. Uhe 1151 (K); G. Uhe 1190 (K); 1964, P. Ralston (K)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive cultivated	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced cultivated	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 555)
Ecuador (Galápagos Islands) Isabela Group	Isabela Island	introduced cultivated	Charles Darwin Foundation (2008)
Ecuador (Galápagos Islands) Isabela Group	Volcán Sierra Negra, Isabela Island	introduced cultivated	Charles Darwin Foundation (2008)
French Polynesia Marquesas Islands	Ua Huka (Huahuna, Uahuka) Island	introduced cultivated	Lorence, David H./Wagner, Warren L. (2013)
French Polynesia Marquesas Islands	Ua Huka (Huahuna, Uahuka) Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2003) (voucher ID: PTBG 40851) Taxon name on voucher: Olea europaea subsp. europaea
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Grant, Martin Lawrence;Fosberg, F. Raymond/Smith, Howard M. (1974) (p. 29) Voucher cited: Grant 4357 (BISH, MIN)
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Cultivée
French Polynesia Austral (Tubuai) Islands	Raivavae (Raevavae) Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Voucher cited: J. Florence 5724 (PAP) Cultivée
French Polynesia Austral (Tubuai) Islands	Raivavae (Raevavae) Island		Bishop Museum (Honolulu) (1983) (voucher ID: BISH 553662) Taxon name on voucher: Olea europaea L.
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 209)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 992-994)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Lorence, David H./Flynn, Timothy W./Wagner, Warren L. (1995) (p. 42) subsp. africana; vouchers cited: D. Lorence & T. Flynn 7604 (PTBG), T. Flynn & Kawakami 3536 (BISH, PTBG) Abundantly naturalized.
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive cultivated	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2010) (p. 65) Voucher cited: Starr & Starr 070403-03 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Starr, Forest/Martz, Kim/Loope, Lloyd L. (1999) (p. 13) East Maui. Subsp. cuspidata, voucher cited: Starr & Martz 971114-2 (BISH); subsp. europaea, voucher cited: Starr & Martz 980817-1 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Frohlich, Danielle/Lau, Alex (2010) (p. 12) Voucher cited: K. Kawelo USARMY 92 (BISH)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced cultivated	MacKee, H. S. (1994) (p. 108) Vouchers cited: Hürlimann 190, MacKee 20617, MacKee 43735
New Zealand (offshore islands) Kermadec Islands	Raoul Island	introduced invasive	Sykes, W. R. (1977) (p. 122) Olea africana Mill.
New Zealand (offshore islands) Kermadec Islands	Raoul Island	introduced invasive	Sykes, W. R./West, C. J. (1996) (p. 456) Subject of eradication program.
New Zealand (offshore islands) Kermadec Islands	Raoul Island	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 881) "confined to the Terraces". Subject of eradication program. "At present there are no mature plants on Raoul".
Tonga Vava‘u Group	Vava‘u Island	introduced cultivated	Space, James C./Flynn, Tim (2001) (p. 67) Cultivated in botanical garden.
United States (other Pacific offshore islands) Midway Atoll	Sand Island	introduced cultivated	Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (pp. B-11) subsp. cuspidata

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	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (p. 120) Also South Australia, Victoria and Western Australia.
Australia Australia (continental)	Australia (continental)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Australia Australia (continental)	Queensland	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (p. 120)
China China	China (People's Republic of)	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Owen, S. J. (1997)
New Zealand New Zealand	New Zealand (country)	introduced invasive cultivated	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 881) "Open coastal scrub and modified areas near indigenous forest margins".
Singapore Singapore	Singapore (Republic of)	introduced cultivated	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 64) Cultivated only
Taiwan Taiwan Island	Taiwan Island	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)

Comments:  Noxious weed in South Australia.

"Norfolk Island was settled by Europeans in 1788 and soon after the African Olive (Olea europaea subsp. cuspidata) was introduced as a fence post timber. This sub-species is a vigorous growing tree with small fruit (about 1cm long). The abundant fruit is not used domestically or commercially." As the Norfolk Island native forest was cleared, the African olive became a major weed and quickly established dense closed monoculture forests. The climate suits the sub-species very well and most of the abundant seed crop germinates.

"In 1984, some 120 ha of the Norfolk Island National Park was dense olive and this area was designated as a Forestry Zone, to be cleared and planted with the native Norfolk Island Pine (Araucaria heterophylla). Control of olive in the rest of the Park will remain a significant ongoing problem for the rest of the century." (Paul Stevenson, 1997)

Control:  For additional control information see the information sheet from Weedbusters New Zealand.

Physical:  "Grazing reduces new seedling volunteering" (Motooka et al., 2003).

Chemical:  "Large olive trees injured by cut-surface applications of triclopyr, glyphosate and 2,4-D, in descending order of severity, although the kill rate was low at one year after treatment. Continuous ring cut-surface applications or drilling should provide effective kill. Saplings very sensitive to basal bark application of triclopyr at 4% product in diesel oil. Mature trees have proved tolerant to soil applications of hexazinone and tebuthiuron.  Crown and root sprouting of herbicide treated trees should be expected and retreatment planned"  (Motooka et al., 2003).