Ricasolia virens
![Ricasolia virens](https://amazon.clikpic.com/lichen/images/r._virens_resized.jpg)
This lichen has a very rich green velvety colour when wet. It is very distinctive and like this painting it is often fertile with lots of reddish brown apothecia. The thallus is adpressed and so this lichen molds itself to the shape of the branch it is growing on.