Colocasia is a genus of flowering plant belongs to the family Araceae native to South Eastern Asia and Indian subcontinent. Some species are widely cultivated and naturalized in other tropical and subtropical regions. Different varieties of Colocasia are seen in Kerala of which Colocasia aquatilis is labeled as an aggressive weed that grows in dense clusters along lake shores and riverbanks, displacing native shoreline vegetation. . Qualitative analyses of two samples are done using crude extract from both the varieties. Antimicrobial activity of wild variety is evaluated in both gram positive and gram negative bacteria using pure extract. Even though both comprise the same genus Colocasia, significant differences were seen in the result of these varieties. In our work , we have used two common varieties of Colocasia one is edible variety Colocasia gigantea and other one a a weed Colocasia aquatilis