Taxonomic name: Acacia confusa Merr.
Synonyms: Acacia richii auct. Non A. Gray, Racosperma confusum (Merr.) Pedley
Common names: acacia petit feuille (Seychelles), boiffuring (Guam), boiffuring (Chamorro-Commonwealth of the Northern Mariana Islands), formosa acacia (English), formosa koa (English), ianangi (English), ianángi (Palau), mimosa (Seychelles), pilampwoia (Pohnpei), shoshigi (Guam), shoshigi (Chamorro-Commonwealth of the Northern Mariana Islands), small Philippine acacia (English), soschghi (Carolinian-Commonwealth of the Northern Mariana Islands), sosigi (Guam), sosigi (Chamorro-Commonwealth of the Northern Mariana Islands), sosugi (Guam), sosugi (Chamorro-Commonwealth of the Northern Mariana Islands), yanangi (Palau)
Organism type: tree, shrub Acacia confusa, a native of northern Philippines, has been introduced to many places throughout Asia and the Pacific. Being well suited to warm moist environments it has become invasive in many of the places of introduction, including Hawai‘i and the Northern Mariana Islands and shows potential to become invasive in others, including Micronesia and Palau. It would probably be wise not to introduce this species to islands where it is not already present. Description
Small tree; adult foliage of falcate phyllodes, juvenile and sucker-shoot foliage of bipinnate leaves; trunk up to 1m thick in very old trees; phyllodes alternate, coriaceous, parallel-curving-veined, 8-10cm long, narrowed at both ends; flowers yellow, in small globose heads 6-8mm in diameter; heads 1 or 2 in axil of phyllode; pods few together, linear or somewhat curved, flat or slightly twisted, brown, 5-10cm long, 1cm broad or a little more or less, with about 8 seeds; seeds compressed, brown (Stone, 1970, in PIER, 2002). The leaves are apparently allelopathic since the ground underneath these trees is free of weeds, (© 1999-2003 Shaman Australis Botanicals). Occurs in:
ruderal/disturbed Habitat description
"This thorny, deciduous shrub grows to 4 metres in height, sometimes forming impenetrable thickets, although in most areas it forms a more open cover" (Smith, 1985. In PIER, 2002). "Erect much-branched shrub; leaves with 4-8 pairs of pinnae, pinnae with 10-12 pairs of small asymmetric leaflets ; stipular thorns straight and slender; flowers in pedunculate axillary heads, 1-3 heads together, subglobose; flowers yellow, fragrant; heads about 1-1,5cm across; stamens numerous; pods dark brown or black, up to 8cm long, to 12mm broad, plump, often slightly curved; pulp within sweetish; seeds compressed, elliptic, brown" (Stone, 1970, in PIER, 2003) (differences according to Paiva, 1999). General impacts
Acacia confusa forms monotypic stands (PIER, 2003). Uses
Medicinal/culinary uses. (Thomas & Randall) Notes
Acacia confusa is being planted in Micronesia. It is a major pest elsewhere. While little reproduction was noted in planted stands, the species should be monitored for invasive behaviour. It would probably be wise not to introduce the species to islands where it is not already present, (PIER, 2003). An older (probably pre-war) tree was observed in limestone forest on Saipan with no reproduction and a native forest understory, which would indicate limited invasiveness. Some naturalising was noted on Rota. (PIER, 2003) Geographical range
Native range: The Northern Philippines, China and Taiwan.
Known introduced range: Commonwealth of the Northern Mariana Islands, Federated States of Micronesia, Guam, Hawai‘i, Palau, Indonesia, Peninsular Malaysia, Japan, Mauritius, and Seychelles. Introduction pathways to new locations
Other: Was planted for windbreaks on Maui, Hawaii. (PIER, 2003)
Local dispersal methods
For ornamental purposes (local): Spread through ornamental plantings. (PIER, 2002)
Forestry (local): Spread through forestry. (PIER, 2002) Management information
Preventative measures: A Risk Assessment of Acacia confusa for Hawai‘i and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a score of 10 and a
recommendation of: "Likely to cause significant ecological or economic harm in Hawai‘i and on other Pacific Islands as
determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘i and/or
other parts of the world." Chemical: Saplings sensitive to foliar application of 2,4-D at 1 lb/acre and of triclopyr at 1 lb/acre in a trial at
Wailua, Kauai. Triclopyr at 2 lb/acre provided 80% control but 2,4-D at 2 lb/acre caused moderate injury and metsulfuron at
0.4 oz active/acre was ineffective at Kala’e, Molokai. Somewhat tolerant of dicamba. Sensitive to cut-surface applications of
2,4-D, dicamba, glyphosate, picloram (45) and triclopyr in trials at Wailua, Kauai. However, in trials at Kala’e, Molokai,
results were less impressive with picloram and dicamba providing serious but not lethal injury and glyphosate and 2,4-D
providing moderate injury to Formosan koa. Sensitive to very-low volume basal bark application of 20% triclopyr in oil. Staff
at the Hawai‘i Volcanoes National Park (HAVO) used triclopyr ester at 5% of product in diesel oil applied to the basal bark
(Chris Zimmer, HAVO). Tolerant of tebuthiuron pellets (Motooka et al., 2002 in PIER, 2003). The weed control appendix provides information on chemical, mechanical, physical, biological management options for this species. Information on species description and environmental impacts is also available. Reproduction
Seeds present in the ground can germinate profusely after fire. Can reproduce from cuttings. Spread through forestry and ornamental plantings. (PIER, 2003)
Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG)
|
|
Last Modified: Thursday, 23 March 2006
|
