Epiphytic Occurrence of Azorhizobium caulinodans and Other Rhizobia on Host and Nonhost Legumes.

A large population of Azorhizobium caulinodans was present on Sesbania rostrata; up to 5 x 10 cm were found on leaves and fewer were found on flowers. Although A. caulinodans was also present on the leaves of Sesbania aculeata (nonhost), the populations were much smaller than that observed on S. rostrata. The population of S. aculeata rhizobia on host leaves was less than 30 cm, and their presence on host flowers was sporadic. Aeschynomene afraspera and Aeschynomene aspera rhizobia, which are profusely stem nodulating, were found on the leaves of host and nonhost plants and on the flowers of host plants, but, Aeschynomene pratensis and Aeschynomene sensitiva rhizobia were not found on the leaves and flowers of host plants.