Abstract
R. alceifolius is a robust, aggressive perennial scrambling shrub, spreading by long arching spiny stems, rooting at their tips, as well as by bird-dispersed seeds. It can develop dense impenetrable thickets. It is native to tropical SE Asia but has been introduced to a number of other territories, most notably the Indian Ocean island of La Réunion, where it is one of the eight most threatening plant invaders to become established on the island and occurs not only on sites disturbed by man but also in primary forest with minimal disturbance (Macdonald et al., 1991). It can behave as a liana, climbing into the canopy of forest trees and increasing the risk of wind damage. It occurs also on the islands of Mayotte, Mauritius and Madagascar (Vos, 2004; Kueffer and Lavergne, 2004a,b) and in Queensland, Australia where it is invading pastures, roadsides, creekbanks, sugarcane plantations and the edges of rainforest (Queensland Government, 2012). Holm et al. (1979) record it as a 'principal' weed in Australia, and risk assessment by the Australian method gave a score of 11 (PIER, 2012). Binggeli et al. (1998) classified it as highly invasive in the tropics. In a joint project between USDA and the Weed Science Society of America it was identified among the highest-ranked potential future invasive weeds in USA (Parker et al., 2007; WSSA, 2012).