Frankia strains in Datisca nodules appear closely related or identical to those that infect Coriaria, Ceanothus, and the actinorhizal Rosaceae (Benson and Clawson, 2000; Benson, et al., 1996; Mirza, et al., 1994).  In fact, crushed nodule inoculations suggest that Dryas, Ceanothus, Datisca and Coriaria are in the same cross-inoculation group (Kohls, et al., 1994; Mirza, et al., 1994; Torrey, 1990).  The diversity and distribution of datisca frankiae in soils has not been extensively studied.  Some work indicates that the distribution of strains parallels the distribution of plants on a regional scale.  In Pakistan, all soils tested yielded nodules on Datisca except one from an eroded area (Mirza et al., 1994).  Companion experiments testing for the nodulation of Coriaria with the same soils yielded less nodulation with some soils failing to nodulate, indicating that Coriaria nepalensis was more difficult to nodulate, in agreement with previous observations (Bond, 1962).