Invasive species have been the subject of several definitions. Most of these definitions closely link exoticism to invasion. In other words, an invasive plant is at first exotic. Thus, according to Clare et al., (2000), an exotic species is a species that occurs outside of its normal range.
An invasive species is defined by IUCN (2000) in Clare et al., (2000) as an exotic species that establishes itself in a natural or semi-natural ecosystem or habitat, which induces changes and threatens endemic biological diversity.

The study identified seven (7) invasive plants including four (4) in drained environments (Prosopis juliflora, Sida cordifolia, Calotropis procera and Pergularia tomentosa) and three (3) in aquatic environments (Mimosa pigra, Eichornia crassipes and Typha australis).