Great Basin Naturalist


There is little information available regarding symbiotic nitrogen fixation by desert plants, particularly with respect to the group of nodulated non-legumes. Early investigations of nodules on non-legumes were contemporary with early studies of the Leguminoseae; however, comparatively little is known even now regarding the extent to which non-legumes fix nitrogen.

A review of literature regarding changes in concepts of nitrogen fixation by legumes and nodulated non-legumes is presented.

Evidence from recent studies on nodulated non-legumes, including those in desert areas, indicates some 31 species of 21 genera in 12 new or previously unrecognized plant families show nodulation with implications of nitrogen fixation.

Some biological aspects of symbiotic nitrogen fixation are discussed, and reports in the literature of nitrogen fixation in natural plant populations are reviewed.

Nitrogen fixation reactions in the desert environment are considered in terms of the areas of investigation needed to help define (1) the magnitude of nitrogen fixation, (2) the extent of nodulation in non-legume plants, and (3) factors affecting this nodulation in the desert ecosystem.