Caesalpinia decapetala (tree, shrub)

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Taxonomic name: Caesalpinia decapetala (Roth) Alston Synonyms: Biancaea decapetala (Roth), Biancaea sepiaria (Roxb.) Tod., Biancaea sepiaria (Roxb.) Todaro, Caesalpinia decapetala var. japonica (Sieb. & Zucc.), Caesalpinia sepiaria Roxb., Reichardia decapetala, Reichardia decapetala Roth Common names: bois sappan (French), cat's claw, kraaldoring (Afrikaans), liane croc chien (English), Mauritius thorn (English), mauritiusdoring (Afrikaans), Mysore thorn (English), puakelekino (Hawaii), sappan (French-Reunion (La Réunion)), shoofly (English), ubobo-encane (Zulu), ufenisi (Zulu), ulozisi (Zulu-South Africa), wait-a-bit (English) Organism type: tree, shrub Originating from Tropical Asia, Caesalpinia decapetala has been introduced to many different tropical locations. It has become a major invasive plant in South Africa and Hawai‘i, where it presents formidable opposition for ranches and has the capability to take over large areas of land. This deciduous, sprawling noxious shrub, with numerous spines, forms impenetrable thickets limiting animal movement and smothering other plants. Description It has been described as a robust, thorny, evergreen shrub 2-4m high or climber up to 10m or higher; often forming dense thickets; the stems are covered with minute golden-hair; the stem thorns are straight to hooked, numerous, and not in regular rows or confined to nodes. The leaves are dark green, paler beneath, not glossy, up to 300mm long; leaflets up to 8mm wide. The flowers are pale yellow, in elongated, erect clusters 100-400mm long. Fruits are brown, woody pods, flattened, unsegmented, smooth, sharply beaked at apex, ± 80mm long (PIER, 2002). Occurs in: natural forests, planted forests, range/grasslands, ruderal/disturbed, water courses Habitat description In the Pacific, the plant is confined to dry to mesic lowland habitats (PIER, 2002). However, in South Africa the plant is found throughout the eastern seaboard in areas that experience high summer rainfall (> 750mm/pa). Altitudinal range is varied and goes from sea level to 1500 m.a.s.l (Wildy, E. pers. comm., 2004) General impacts Grows into impenetrable thorny thickets limiting passage of animals. May overgrow exisiting vegetation. Invades forest margins and gaps, plantations, roadsides and watercourses (PIER, 2002). C. decapetala scrambles over and smothers other species, including tall forest trees. It hinders access to plantations and riverbanks. It retards growth of saplings in newly established plantations. Further more, infestations along riverbanks are likely to affect streamflow. Uses Used as security hedging or a barrier. Sometimes used as an ornamental. Notes The average temperatures in the areas where Mysore thorn is endemic ranges from 50-over 68 F (10-over 20 C) in January to 68-over 86 F (20-over 30 C) in July. The average annual rainfall in these areas is approximately 40 - over 80 in (100 - over 200cm) (Hammond 1986). In South Africa, C. decapetala is commonly found in areas that receive between 750mm and 1000mm of rain per annum. (Wildy, E. pers. comm., 2004). Geographical range Native range: India. Known introduced range: Fiji, French Polynesia, Hawai‘i, New Caledonia, Norfolk Island, Australia, China, Japan, Korea, Indonesia, Malaysia, Philippines, Thailand, Vietnam, Mauritius, La Réunion, Rodrigues, South Africa. Introduction pathways to new locations Other: First introduced by ranchers for fencing (Starr et al., 2003) and missionaries who planted it to keep out wild animals (WESSA, 2004). Local dispersal methods Consumption/excretion: Birds or rodents. (Smith, undated) Other (local): Wherever the vine-like stems touch moist ground they take root and form new plants. They also take root on old trunks, cut and used for fence posts (Starr et al. 2003). Translocation of machinery/equipment (local): Thought to have been introduced to Maui on equipment from another island during construction of the new bridge. (Starr et al. 2003) Water currents: The large seeds are carried down streams to form new infestations. (Smith, undated) Management information Preventative measures: A Risk Assessment of Caesalpinia decapetala 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 20 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: Mysore thorn is sensitive to foliar applications of glyphosate and triclopyr, and to soil applications of tebuthiuron. Adequate coverage of Mysore thorn foliage in dense infestations is difficult. Timely repeat applications (3-9 months) of triclopyr ester at 113.4grms/acre (0.25 lb/acre) allows gradual reductions and opening of the canopy and eventual control. This strategy not only stresses the Mysore thorn over a longer period but also controls newly germinated Mysore thorn seedlings. Accessible stems may be treated basal bark with triclopyr ester at 20% product in diesel or crop oil in very low volume applications (PIER, 2002). Reproduction The medium-sized seeds may be dispersed by rodents and granivorous birds, but man is almost certainly the principal dispersal agent in Hawaii (PIER, 2002). Trailing branches root where they touch the ground (WESSA, 2004). The seed is spread considerable distances by running water (Starr et al. 2003). It is thought that in Maui the introduction may have been the result of seeds in mud on large machinery used to do road work on the Hana Hwy. (Starr et al. 2003). Reviewed by: Eden Wildy. Alien Invader Plants Project. Wildlife & Environment Society of SA. South Africa. Principal sources: Pacific Islands Ecosystems at Risk, 2002. Caesalpinia decapetala Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG) To contribute information, please contact Shyama Pagad. Last Modified: Monday, 27 March 2006