Acacia nilotica (L.) Willd. ex Delile, Fabaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Risk assessment results: 

Reject, score: 13 (Go to the risk assessment (Australia))
High risk, score: 14 (Go to the risk assessment (Pacific))

Other Latin names:  Acacia arabica (Lam.) Willd., Acacia adansonii Guill. & Perr., Acacia adstringens (Schumach.) Berhaut

Common name(s): [more details]

English: babul, Egyptian thorn, gum arabic tree, Nile acacia, prickly acacia, thorny acacia

French: acacia à gomme, gommier rouge

Other: tiare

Spanish: acacia gomifera

Habit:  tree

Description:  "A shrub or small tree from 7 to 9 m high, having feathery leaves… Stems: Whitish and pubescent when young becoming darker with age; woody; to 7 m long, branching almost from the base. Leaves: Bipinnate, consisting of 3 to 10 pairs of primary leaf segments 3.5 to 4 cm long, each bearing 10-to 25 pairs of linear-oblong leaflets 3 to 6 mm long, 0.5 to 1.5 mm wide; a petiolar gland occurs between the 2 pairs of segments closest to the stem; a pair of stout stipular spines, 5 to 50 mm long, occurs at the base of each leaf on younger stems but may be absent on older stems. Flowers: Bright yellow, numerous, in fluffy globular heads 1.2 cm diameter, usually in clusters of 2 to 6, on individual pubescent axillary stalks 1.5 to 2 cm long, each stalk with pair of bracts near its mid-point. Fruit: Gray-green, softly hairy flattened pod 6 to 25 cm long, 1 to1.5 cm wide, strongly constricted between each seed; pods slightly sticky internally. Seed: Depressed, subglobular. Root: A deep woody taproot with several branching surface laterals" (Parsons and Cuthbertson, 1992; pp.435-438).

Habitat/ecology:  "Grassland, savanna"  (Weber, 2003: p. 18).  In New Caledonia, "abondamment naturalisé dans un secteur côtier de la commune de Paita; non vu ailleurs. Considéré comme un arbre fourrager utile bien que les jeunes pieds épineux forment des fourrés difficiles à pénétrer" (MacKee, 1994; p. 76). Arid lowlands in the Galápagos Islands (McMullen, 1999; p. 67). Favors steams in semi-arid areas.

Propagation:  Seed. Seeds can remain dormant in the soil for long periods. Seeds are eaten by cattle and spread by passing through the digestive system.

Native range:  Africa and western Asia

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced invasive cultivated	Charles Darwin Research Station (2005)
French Polynesia Society Islands	Tahiti Island		Fosberg, F. R. (1997) (p. 46)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 381) Abondamment naturalisée dans un secteur côtier de la commune de Paita; non vu ailleurs. Les jeunes pieds épineux forment des fourrés difficiles à pénétrer.
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	MacKee, H. S. (1994) (p. 76) Vouchers cited: MacKee 21696, MacKee 24794, MacKee 34586, MacKee 40252
New Caledonia New Caledonia Archipelago	Île Grande Terre		Bishop Museum (Honolulu) (1978) (voucher ID: BISH 664461) Taxon name on voucher: Acacia nilotica (L.) Willd. ex Delile
Solomon Islands Solomon Islands	Solomon Islands	introduced cultivated	Hancock, I. R./Henderson, C. P. (1988) (p. 43)
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis and Futuna Islands		Waterhouse, D. F. (1997) (p. 59)

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)	Northern Territory	introduced invasive	Smith, Nicholas M. (2002) (p. 14)
Australia Australia (continental)	Northern Territory	introduced invasive	Australian Biological Resources Study (2007)
Australia Australia (continental)	Queensland	introduced invasive	Smith, Nicholas M. (2002) (p. 14)
Australia Australia (continental)	Queensland	introduced invasive	Australian Biological Resources Study (2007)
China China	China (People's Republic of)	introduced	ILDIS Co-ordinating Centre (2005)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)	introduced invasive	Cronk, Q. C. B./Fuller, J. L. (2001) (p. 133)
Indonesia Indonesia	Indonesia (Republic of)	introduced invasive	Pallawatta, Nirmalie/Reaser, Jamie K./Gutierrez, Alixis T./eds. (2003) (p. 31)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced	ILDIS Co-ordinating Centre (2005)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Rodrigues Island	introduced	ILDIS Co-ordinating Centre (2005) subsp. adstringens

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)	United States (other states)	introduced	ILDIS Co-ordinating Centre (2005)

Comments:  One of Australia's worst environmental weeds.

Proposed for eradication in the Galápagos Islands (Chris Buddenhagen, pers. com.).

Control: 

Physical: Single trees can be grubbed, cutting the root at least 30 cm below the surface to prevent sprouting. Some control can also be obtained by burning or mowing.

Chemical: Triclopyr in diesel oil may be used as a basal bark or cut stump treatment. Tebuthiuron granules may be applied from the air. For larger trees, picloram or liquid hexazinone may be injected into the main stem at 8 cm intervals when the tree is in full leaf.

Biological: Being investigated in Australia. See Julien (1992) and Parson and Cuthbertson (1992; pp. 435-438).  "THe seed-feeding bruchid, Bruchidius sahlbergi, has been released in Australia"  (Cronk & Fuller, 2001; p. 133).

Additional information:  At the Woody PlantEcology web site.
Fact sheet from the Department of Natural Resources, Queensland, Australia. (PDF format)
Information from the Purdue University NewCROP web site.
Information from the World Agroforestry Centre's AgroForestryTree Database.

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

Taxonomic information about Acacia nilotica 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.

Bishop Museum (Honolulu). 1978. Voucher specimen #BISH 664461 (Mackee, H.S. 34586).

Charles Darwin Research Station. 2005. CDRS Herbarium records.

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

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

Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe. 1996. Conséquences des introductions d'espèces animales et végétales sur la biodiversité en Nouvelle-Calédonie. Rev. Ecol. (Terre Vie) 51:375-401.

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

ILDIS Co-ordinating Centre. 2005. International Legume Database & Information Service. Online searchable database.

Julien, M. H. (ed.). 1992. Biological control of weeds: A world catalogue of agents and their target weeds (third edition). CAB International, Wallingford, UK. 186 pp.

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

McMullen, C. K. 1999. Flowering plants of the Galápagos. Comstock Pub. Assoc., Ithaca, N.Y. 370 p.

Pallawatta, Nirmalie/Reaser, Jamie K./Gutierrez, Alixis T./eds. 2003. Invasive alien species in south-southeast Asia: national reports and directory of resources. Global Invasive Species Programme. 111 pp.

Smith, Nicholas M. 2002. Weeds of the wet/dry tropics of Australia - a field guide. Environment Centre NT, Inc. 112 pp.

Swarbrick, John T. 1997. Weeds of the Pacific Islands. Technical paper no. 209. South Pacific Commission, Noumea, New Caledonia. 124 pp.

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

Waterhouse, D. F. 1997. The major invertebrate pests and weeds of agriculture and plantation forestry in the Southern and Western Pacific. The Australian Centre for International Agricultural Research, Canberra. 93 pp.

Weber, Ewald. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK. 548 pp.

Wiggins, I. L./Porter, D. M. 1971. Flora of the Galapágos Islands. Stanford University Press. 998 pp.