Is This An Invasive Plant? What Do You Call It?

Could anyone please tell me the name of this "alien" plant as my cousin calls it...growing amongst my purple hearts. My neighbor had given me a tiny piece and its growing kind of fast. My cousin said to get rid of it ASAP as it has taken over her property, lol!

Original article and pictures take http://www.hometalk.com/1237822/is-this-an-invasive-plant-what-do-you-call-it site