Native species are plants that naturally occur in a specific landscape and climate. These species are ecologically and climatically suited to their environment, having co-evolved and adapted over time to changing conditions. They play a crucial role in maintaining and enhancing ecosystems, serving as a primary food source for local wildlife. Native plants are ideally suited to the local soil, micro-climate, and topography, allowing them to thrive in their natural niches. These species vary across different agro-climatic zones, with distinct biodiversity found in various regions such as the Himalaya, the deserts of Rajasthan, the semi-arid landscapes of central Maharashtra, the evergreen forests of Kerala, and the mangroves of the Sundarbans. 

 

There are few other terms as well that describe ‘Native’, such as ‘Local species’, ‘Indigenous species’.

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Whereas, Exotic species are those plant species, which are not native to a particular area. These species have been introduced by human activities to a location where they do not naturally occur and so they are termed "exotic", "non-indigenous", "non-native" or simply "alien". The exotics threaten to alter the natural composition of forest; they restrict, prey on or compete with native populations and disrupt the integrity of site. They are major ecological threat. Some research suggests that the plant inhibits the growth of other plants in its vicinity.

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When these non-native species cause ecological problems, they are termed as "invasive" or "harmful exotic species". Many times they turn out into a weed. Such species primarily invades disturbed habitats, degraded forests / thickets and left out or fallow fields crowding out native vegetation of upland forests, forming single species stands. For Example: In India, once introduced, the species like Lantana camara (Tantani) becomes invasive and slowly suppresses the growth of original vegetation. Once it starts flowering and fruiting, the seeds spread over a large area and germinate very fast. Then it becomes very difficult to eradicate them. Some of them are prolific seed producers. One can observe many such examples like Australian Acacia, Gliricidia spp. and Leucaena leucophyla (Subabhul). They start growing easily from the cut stump.

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