Useful Trees and Shrubs in Dryland Permaculture : Useful Trees & Shrubs in Dryland Permaculture : 9780692936412 : 0692936416 : 10 Aug 2017 : The reason I wrote this book is simple. There are so many of us in permaculture who still have trouble remembering which leaves, seeds, seed pods, flowers, and general tree shapes belong to some of the important Nitrogen Fixers and other trees that are often used in dryland permaculture. I also included several trees that most permaculture folks like to use due to their usefulness in producing foods, medicines, and for attracting beneficial insects. For those of you who don't yet know, a Nitrogen Fixer is a tree or plant that has little nodules on its roots that house a very wonderful type of bacteria. This bacteria actually converts the Nitrogen from our air into deep, ground-penetrating fertilizer, and the leaves of these plants and trees are also an excellent source of high nitrogen fertilizer! Imagine what these wonderful plants can do for any