Parthenium commonly called as carrot grass is an exotic species which came to India and has become most noxious terrestrial weed. African cat fish Clarius garpienus is posing threat to indigenous catfish of our rivers. Rauwolfia vomitoria growing in different Himalayan ranges produces an active chemical called as reserpine. This single species might show high diversity at
the genetic level over its distributional range. Lantana camera is a toxic producing plant.