Plants for Turtles...

Anyone have any ideas on whether calamus (acorus calamus, sweetflag) is safe for turtles? I will be getting my box turtles soon and am getting their habitat together, a piece at a time. I'd like to include some plants, and am looking online for organic potted plants that are safe for turtles. I'm not having much luck finding organic potted plants, but I have found a couple. So, we'll see. I may buy some dandelion greens from work (I work in grocery) and see if they can be planted!

I'm going to be putting the enclosure together this week and next. :) It's to be 40 inches long and 22 inches wide, 16 inches tall (ten inches of wood with 6 inches of plexiglass). I'm pretty excited!