An overview of exotic weed species that occur in Papua New Guinea is given by Orapa (2001) and Waterhouse (Waterhouse 2003). In waterways salvinia (Salvinia molesta), a small water fern, and the water hyacinth (Eichhornia crassipes) had seriously invaded but biological control has been successful (Orapa 2001). Important introduced weeds that are found in various parts of Papua New Guinea include Rottboelia cochinchinensis, Sida acuta, Sida rhombifolia, Cyperus rotundus, Pennisetum purpureum, Imperata cylindrica, Mimosa invisa, Mimosa pudica, Mikania micarantha and Eicchhornia crassipes. Orapa (2001) considers the following invasive species lesser known introduced plants with the potential to become widespread weeds: Chromolaena odorata, Mimosa pigra, Melinus minutiflora, Clerodendrum chinensis, Partheniu hysterophorus, Stachytarpheta urticifolia, Sorghum halepens, Spathodea campanulata and Azadirachta indica. Piper aduncum is also listed by (Orapa 2001) as a newly introduced weed that has the potential to become an aggressive invader. It already is. 

 

Orapa, W. (2001). Impediments to increasing food security in PNG: the case of exotic weed species. Food Security for Papua New Guinea. Papua New Guinea Food and Nutrition 2000 Conference. R. M. Bourke, M. G. Allen and J. G. Salisbury. Papua New Guinea University of Technology, Lae, Australian Centre for International Agricultural Research. 99: 308-315.

 

Waterhouse, B. (2003). Know your enemy: recent records of potentially serious weeds in northern Australia, Papua New Guinea and Papua (Indonesia). Telopea 10: 477-85.