<P> Inga alley farming relies on the leguminous genus Inga, a small tropical, tough - leaved, nitrogen - fixing tree . </P> <P> Although by far the majority of plant species able to form nitrogen - fixing root nodules are in the legume family Fabaceae, there are exceptions: </P> <Ul> <Li> Parasponia, a tropical genus in the Cannabaceae also able to interact with rhizobia and form nitrogen - fixing nodules </Li> <Li> Actinorhizal plants such as alder and bayberry can also form nitrogen - fixing nodules, thanks to a symbiotic association with Frankia bacteria . These plants belong to 25 genera distributed among 8 plant families . </Li> </Ul> <Li> Parasponia, a tropical genus in the Cannabaceae also able to interact with rhizobia and form nitrogen - fixing nodules </Li>

Differentiate between high energy nitrogen fixation and biological nitrogen fixation