One of the most beautiful sights in nature is the changing colour of autumn leaves (or fall leaves in the US). Other than haemoglobin and myoglobin, virtually all of the biological pigments covered in this sub-topic can be found in autumn leaves.Image taken during an autumn visit to Westonbirt arboretum in the UKThe leaves on trees contain many plant pigments but the dominant one during the spring and summer is chlorophyll....