" How does a tree breathe anyway? You can see a part of its “lungs.” These are the needles or leaves. They have narrow slits on their undersides that look a bit like tiny mouths. The tree uses these openings to exhale oxygen and breathe in carbon dioxide. At night, when the tree is not photosynthesizing, it does the reverse. "

― Peter Wohlleben , The Hidden Life of Trees: What They Feel, How They Communicate: Discoveries from a Secret World