I've been doing some work this week with ideas about photosynthesis, and I have been struck by the idea that plants - or trees in this case - are just solid sky. Most of the new material that forms growing trees comes from carbon dioxide in the air, so a plant becomes solid air. That made me think about the link between the sky and trees. I found one photograph from a month or so back that seemed to express that idea, but I also managed to take some on the walk home from work. The first picture is of Mountain Ash - these can grow to be the tallest flowering plants in the world. The next images are of an Angaphora species - its growing on a railway cutting near my office!