The term ‘exotic’ has been used as a misnomer to define and describe ‘invasive alien species’ in many places. It is imperative to distinguish the ‘exotic species’ from ‘invasive species’ for scientific as well as for management purpose.

Exotics

Organisms that have moved away from their natural geographical range are termed as exotics in new land. The movement is either or intentional or accidental. Exotics dominate many ecosystems and alter tremendously the composition and function. Exotic species are also called as alien species.

Naturalised

The alien or exotic plant that went out of it natural range, harmonises with the natural system and survives. These plants do not out-compete the indigenous plants for space or nutrition.

Invasive

The exotic plants compete with the native plants and take over the habitat for survival and establishment. Species that are able to exploit the available resources invade the community. The specific functional traits of an alien species determine it to be invasive or naturalized.

1274 species of recorded plants in the state are alien or exotic; but amongst this, only 276 are naturalized or invasive, subject to habitat localization. Yet, there are hardly few plants that are classified as serious invading species separately in terrestrial and wetland habitats. Major species include Lantana, Chromolaena, Prosopis juliflora, Wattle, Pine, Opuntia, Cestrum, Parthenium, etc. Consequently, invasion occurs when niche vacancy exists following disturbances that increase resource availability or when competitors and natural enemies suppress indigenous species performance. The ability to exploit available resources depends on functional differences among species, which are considered proportional to invasive ability.