Purple Angel Trumpet Tree

This Angel Trumpet Tree is at John and Jeanette's house. This is the first year, and has tripled in size already. I have tried this plant 2 different times, and they did not come back the following year, in our area. I suggested they keep some of these seeds in a safe location. Also, if they are like the Datura-Angel Trumpet they are poisonous. Don't really know for sure, but there are a lot of house plants that are poisonous.