The setup: A thick mountain chain is permanently covered in smoke. The smoke comes from several active volcanoes within the mountains, and is kept from dispersing by magic (the magic plays virtually no other part in this scenario). The smoke varies in thickness, but is consistently thick enough to make traveling through it near-impossible, due to the lack of visibility. The magic plus the smoke combine to make a weak greenhouse effect, meaning the mountain chain as a whole is fairly warm (think 90-110 degrees Fahrenheit in spring/fall (a lot of heat comes from the volcanoes)).
It makes sense to me that such thick smoke would block a good portion of sunlight from reaching the ground, and any vegetation that might be there. This leads me to the question: what could grow/live there?
The Question: What kind of plants could thrive in such an environment, if any? What animals would be most at home in this environment?