Taxonomy and distribution of non-legume nitrogen-fixing systems

In this chapter more attention will be paid to plants bearing Alnus-type nodules than to other non-legume nitrogen-fixing systems, partly because it has been with the former that the author’s main research interest has lain, but also for the reason that of the various systems to be considered in the chapter, the nitrogen fixation associated with Alnus-type nodules seems to offer the best prospects for exploitation.