Bacteria Type of host Rhizobium | .

Bacteria Type of host

Rhizobium - Roots of several legumes such as alfalfa, sweet clover, sweet pea, lentils, garden pea, broad bean, clover beans etc.

Frankia - Roots of Alnus, Casuarina (non legumes)

Azorhizobium - Stem nodules of Sesbania

Bradyrhizobium and Sinorhizobium - Root nodules of soyabean

Both Rhizobium (rod shaped) and Frankia (filamentous) are heterotrophic, free living forms in soil, but as symbionts, can fix atmospheric nitrogen.