common greenshield

I went outside with my science class to identify lichen and I think I found common greenshield (Flavoparmelia caperata) growing on a living tree outside of our school. The lichen was leafy and growing in kind of a circle formation. It what about a 1 1/2 cm in diameter circle. Its was a dry leafy patch that was green colored. It was 0 degrees Celsius outside at the time and the lichen was still alive. The wind speed at the time was 20 mph, and there was about 2-3 inches of snow on the ground. The tree I found it on was a heathy living tree. It was about ten yards into the wood from the road were i found it.