'I Wonder Why Leaves Change Colour' and other questions about plants, from Kingfisher books. Rrp £5.99 so get it for LESS than half price here! Colourful, surprising and full of information, the I Wonder Why books have set thousands of young minds buzzing. I Wonder Why Leaves Change Colour' is the perfect introduction to plants, featuring meat-eating plants, water plants, smelly plants and more. Glossy paperback. Approx 28cm x 23cm.