When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive and cause decline or extinction of indigenous species. Excessive environmental damage was caused and the threat posed to our native species by invasive weed species like carrot grass(Parthenium), Lantana and water hyacinth (Eicchornia). The recent illegal introduction of the African catfish Clarias gariepinus for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers. All the three are invasive species but Nelumbo is not. So, the correct answer is 'Nelumbo'.