One more post about lava; specifically, lava tubes. We visited the famous Thurston Lava Tube in Volcano National park, a giant tunnel left in the surrounding lava by a flowing lava wave that passed through, hollowing out as it went. The entrance to the tube is in a depression that makes a nice little micro-climate for many ferns, which are draped luxuriously around the entrance. Adiantum is the most common fern in these photos:
Once you get inside the lava tube (next picture), you're not done with the ferns... around every one of the light fixtures installed to illuminate the tunnel, spores have germinated and ferns are growing. A testament if ever there was one to ferns' ability to photosynthesize in low light conditions!