We learn about the individual plant species their ecology , morphology and habitat etc. Truly speaking I came to know about the term invasive species a few years ago but didn't have in depth knowledge about the plant species. And yes when I came to know about the species, it really interesting and I go ogled suddenly and found some facts about the species.An invasive species is a plant or animal that is not native to a specific location, an Introduced species and has a tendency to spread, which is believed to cause damage to the environment, human economy and/or human health.

The term as most often used applies to introduced species, also called "non-indigenous" that adversely affect the habitats and bioregions they invade economically, environmentally, and/or ecologically. Such invasive species may be either plants or animals and may disrupt by dominating a region, wilderness areas, particular habitats, or wildland urban interface land from loss of natural controls .Invasive species often coexist in nature with the extended period of time and gradually become superior to the prior native species and become dominant in the area and adapt in the new site.

An invasive species might be able to use resources that were previously unavailable to native species, such as deep water sources accessed by a long taproot, or an ability to live on previously uninhabited soil types. More interesting finding about the invasive species has shown that introduced populations have great potential for rapid adaptation and this is used to explain how so many introduced species are able to establish and become invasive in new environments.

The species have both the positive and the negative impacts. In Nepal the case is different and during my field visit(as a  research field assistant ) ,we  surveyed about the new species and their impacts in various parts of Kaski district and Chitwan district. People in the village areas point that the species is harmful for their agricultural land.The invade their land so rapidly and cannot remove form the area so easily. They in turn came up with low agricultural production. Invasive plant pathogens and insect vectors for plant diseases can also suppress agricultural yields. Also , in various areas people for the adaptation , make the alternative use of species, these days they used to make the bio briquette from the species like Lantena camera.

Furthermore, they are also causing ecological alteration of the animals and plants. In chitwan which is known for the hot spot of the one horned rhino, one of the invasive species (Mikania micrantha) is causing severe impact in the habitat alteration of the endangered species. Mikania micrantha is also called as mile a minute plant, which literally signifies that they can grow mile in a minute. Mikania micrantha is invading the few areas but we cannot insist that it cannot cover Chitwan National Park  whole  as well, which in turn is changing the habitat structure. According to the news, these days the rhino has shifted feeding habit as well. Due to change in habitat structure, they start to eat the Mikania micrantha which is replacing the other preferred plant species of the one horned rhino.

Although the species is harmful and cause the loss of the native plants and animals, even though its gaining less concern. Such issues need to be addressed in time,so that the loss of natural habitat can be reformed and can make its best use.

Source: http://en.wikipedia.org/wiki/Invasive_species