Tree huggers could have one of those decorated Norfolk Island Pines. My Sam's Club has them every year, and every year I have to just make myself walk away from buying one. They're very pretty. One year I bought one of those rosemary plants shaped like a Christmas tree. I love the smell of rosemary.
I know a little about vegan diets but not much about their ethics. There are plant based vegans who eat "dead" plants, and I'm sure they understand that somebody had to "kill" that plant first
. They might, however, draw the line on killing a plant that is purely for decoration.