Just to warn you, beardies and plants are a bad combination, even if they are safe plants. They typically eat them, crush them, trample them and tear them up, sometimes with remarkable speed. they see the world in very simple terms. They quickly label everything one of 3 things: predator, food or furniture. I tried it with my first dragon, he destroyed 5 in like 3 days.
There are also risks of raising humidity in the enclosure.
But if you want to try it. there's a safe plant list at the bottom of this chart
http://www.beautifuldragons.503xtreme.com/Nutrition.html I would highly recommend you at least use cheap plants you dont' care about.