Ligustrum spp. Oleaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Risk assessment results: 
Reject, score: 11 (Go to the risk assessment for Ligustrum lucidum (Australia))
Evaluate, score: 6 (Go to the risk assessment for Ligustrum lucidum (Pacific))
Evaluate, Score: 6 (Go to the risk assessment for Ligustrum japonicum)
High risk, Score: 11 (Go to the risk assessment for Ligustrum sinense)

Common name(s): [more details]

English: privet

French: troène de Californie, troène de Ceylan, troène des haies

Habit:  shrub/tree

Description:  "Small trees or erect shrubs, sometimes deciduous; leaves simple, short-petiolate, the blades entire, often glandular beneath; inflorescences terminal, thyrsoid or paniculiform, bracteate, the flowers small, 4-merous, subsessile or short-pedicellate; calyx campanulate, truncate or shortly 4-dentate; corolla infundibular or campanulate, the tube equal to or longer than calyx tube, the lobes induplicate-valvate in bud, becoming spreading, slightly shorter than or longer than corolla tube; stamens 2, inserted on corolla tube, the filaments slender, short, the anthers basifixed, ellipsoid or oblong, usually exserted; ovary subglobose, the ovules 2 per locule, pendulous, the style often filiform, the stigma 2-lobed; fruit a carnose berry or somewhat drupaceous, the endocarp chartaceous or membranous, the seeds usually solitary, sometimes 2-4"  (Smith, 1988; pp. 135-136).

Habitat/ecology:  Privets are extremely aggressive and can form dense, impenetrable thickets that crowd out desirable plants. They are prolific seed producers.

Dry, moist, and wet forests, open areas, roadsides, up to at least 6,000 ft. elevation in Hawai‘i. In Australia, Ligustrum lucidum is an invasive species in coastal rainforest and L. sinense naturalizes along fencelines and on the margins of rainforest (Csurhes & Edwards, 1998; p. 174).

Propagation:  Seeds distributed by frugiferous birds (Carr et al., 1992, cited in Csurhes & Edwards, Smith, 1991; pp. 238-239).

Native range:  Eurasia to Malaysia and tropical Australia. Commonly used as hedges and ornamentals.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
American Samoa Tutuila Islands	Tutuila Island	introduced invasive cultivated	Space, James C./Flynn, Tim (2000) (pp. 5, 11) L. sinense?
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive	Csurhes, S./Edwards, R. (1998) (p. 174) L. sinense
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced	Pickard, J. (1984) (p. 207) L. sinense
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 20) L. sinense Lour. "A native of China which has also escaped from cultivation and is proving a serious weed in places". Vouchers cited: A.C. Beauglehole, 5848 (CANB, MEL), J. Pickard 1411 (NSW), J. Pickard 3458 (NSW), J. Pickard 3462 (NSW)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 9) L. lucidum W.T. Aiton "A native of western and southern China which has escaped from cultivation and has proved a serious weed in some places". Voucher cited: W.R. Sykes NI 617 (CHR); L. sinense Lour. "A native of China which has also escaped from cultivation and is proving a serious weed in places". Voucher cited: W.R. Sykes NI 227 (CHR)
Fiji Fiji Islands	Viti Levu Island	introduced cultivated	Smith, Albert C. (1988) (p. 136) Ligustrum sinense. Vouchers cited: DA 9809, DA 12240
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 209) L. japonicum, L. sinense
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Herbarium Pacificum Staff (1999) (p. 6) L. sinense Lour.; voucher cited: T. Tunison s.n. (BISH 605525)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Staples, George W./Imada, Clyde T./Herbst, Derral R. (2003) (p. 16) Ligustrum lucidum Ait., voucher cited: T. Motley, W. Char, B. Pang & C. Imada 1001 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Lorence, David/Flynn, Tim (1999) (p. 5) L. sinense Lour.; vouchers cited: D. Lorence, T. Flynn, S. Joe, F. Kraus, K. Reinard, J. Plews 8149 (BISH, K, MO, PTBG, US), T. Flynn & D. Lorence 6132 (BISH, K, PTBG) Profusely naturalized in Koke‘e State Park.
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive cultivated	MacKee, H. S. (1994) (p. 108) L. lucidum; voucher cited: MacKee 37698 (cult.); L. sinense; vouchers cited: MacKee 1669 (spontané), MacKee 24853 (cult.) Spontané
Samoa Western Samoa Islands	Upolu Island	introduced cultivated	Space, James C./Flynn, Tim (2002) (p. 10) Ligustrum sp. L. sinense? Single cultivated plant in house yard.
Tonga Tongatapu Group	Tongatapu Island	introduced cultivated	Space, James C./Flynn, Tim (2001) (p. 7) Ligustrum sp.

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. 174) L. lucidum, L. sinense
Australia Australia (continental)	Queensland	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (p. 174) L. lucidum, L. sinense
New Zealand New Zealand	New Zealand (country)	introduced invasive	Owen, S. J. (1997) L. lucidum, L. sinense
New Zealand New Zealand	New Zealand (country)	introduced invasive cultivated	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (pp. 878-880) L. lucidum Aiton f., "Naturalised extensively in waste places, margins of remnant forest stands, coastal cliffs, and gardens"; L. ovalifolium Hassk., "Forest remnant margins, roadside banks, and waste places"; L. sinense Lour., "Forest margins, waste places, particularly roadsides and cliffs in and near towns and cities"; L. vulgare L., "Usually on waste land, roadside banks and in and around modified forest remnants".

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	MacDonald, I. A. W./Thebaud, C./Strahm, W. A./Strasberg, D. (1991) (pp. 51-61) L. robustum, L. sinense
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Lavergne, Christophe (2006) Ligustrum robustum (Roxb.) Blume subsp. walkeri (Decne) P.S. Green, "Très envahissant"; Ligustrum ovalifolium Hassk, "Cultivé/naturalisé"
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced invasive	Lorence, D./Sussman, R. W. (1988) (pp. 187-204) L. robustum var. walkeri (Decne.) Mansfr.).
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Rodrigues Island	introduced invasive	Cronk, Q. C. B./Fuller, J. L. (2001) (p. 166) Ligustrum robustum

Comments:  L. robustum Blume var. walkeri (Decne.) Mansfr is reported to be a problem on Mauritius (Lorence and Sussman, 1988) and La Réunion. Some other well-known pest ligustrums are L. lucidum Aiton, L. ovalifolium and L. sinense Lour. All species should be avoided, as several have proven invasive in island ecosystems.

Control:  The Nature Conservancy's Stewardship Abstract contains information on control methods.

Physical: Small plants may be hand pulled; older individuals need to be dug out.

Chemical: Foliar treatment of actively growing plants with glyphosate herbicide. Treat cut stumps to prevent resprouting.

"Foliar applications of glyphosate effective. Katie Cassel (Kōke‘e Museum) reported privet was susceptible to cut-stump applications of triclopyr or glyphosate.  Stems <0.5 inch diameter susceptible to basal bark application of 20% triclopyr ester in oil.  Larger stems must be notched or frilled.  HAVO staff report control with triclopyr amine at 10% of product in water applied to cut stumps  (Chris Zimmer, HAVO).  The manufacturer reported that metsulfuron was highly effective when applied to the foliage of actively growing plants at a rate of 5 grams per 10 liters of water (spray to wet the foliage)"  (Motooka et al., 2003).

Biological: An investigation of possible biological control agents is under way on La Réunion.

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).
Report (PDF format) from US Geological Survey, Biological Resources Division, Haleakala Field Station, Hawaii "Plants of Hawaii".
NRCS Plant Guide for Ligustrum sinense (PDF)
See information on the Environment Bay of Plenty, New Zealand, web site on both L. lucidum and L. sinense.
Fact sheet, including control information, from the Bay of Plenty Regional Council, New Zealand.
Chinese privet (Ligustrum sinense) factsheet (PDF format) from Virginia Department of Conservation & Recreation's invasive plant species list
Photos and additional information on Ligustrum sinense at University of Florida, Center for Aquatic and Invasive Plants.
The Nature Conservancy photos and Stewardship Abstract.
Information from "Invasive plants of Asian origin established in the United States and their natural enemies, volume 1" (PDF format).

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

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

References:

Cronk, Q. C. B./Fuller, J. L. 2001. Plant invaders. Earthscan Publications, Ltd., London. 241 pp.

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

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.

Lavergne, C./Shaw, D. 1999. The invasive behaviour and the biological control of Ligustrum robustum subsp. walkeri on the Mascarene island of La Réunion. Aliens 9:13.

Lavergne, Christophe. 2006. List des especes exotiques envahissantes a La Reunion. Unpublished manuscript (Excel file). .

Lorence, D./Sussman, R. W. 1988. Diversity, density, and invasion in a Mauritian wet forest. Monogr. Syst. Bot. Missouri Bot. Garden 25:187-204.

Lorence, David/Flynn, Tim. 1999. New naturalized plant records for the Hawaiian Islands. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 1998. Part 2: Notes. Bishop Museum Occasional Papers. 59:3-6.

MacDonald, I. A. W./Thebaud, C./Strahm, W. A./Strasberg, D. 1991. Effects of alien plant invasions on native vegetation remnants on La Reunion (Mascarenes Islands, Indian Ocean). Environmental Conservation 18 (1):51-61.

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

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.

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

Owen, S. J. 1997. Ecological weeds on conservation land in New Zealand: A database. Working draft. Wellington, New Zealand. Department of Conservation.

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

Smith, Albert C. 1988. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 4. 377 pp.

Space, James C./Flynn, Tim. 2000. Observations on invasive plant species in American Samoa.  USDA Forest Service, Honolulu. 51 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.

Staples, George W./Imada, Clyde T./Herbst, Derral R. 2003. New Hawaiian plant records for 2001. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2001-2002. Part 2: Notes. Bishop Museum Occasional Papers. 74:7-21.

Timmins, S. M./Mackenzie, I. W. 1995. Weeds in New Zealand protected natural areas database. Wellington, New Zealand. Department of Conservation, , Technical Series No. 8. 287 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.

Zheng, Hao/Wu, Yun/Ding, Jianqing/Binion, Denise/Fu, Weidong/Reardon, Richard. 2004. Invasive plants of Asian origin established in the United States and their natural enemies, volume 1. FHTET-2004-05. U.S. Forest Service, Morgantown.