Root suckering of both Populus tremuloides Michx. and P. grandidentata Michx. commonly produces clones of genetically identical stems, joined, to some extent, through the parent root system. Excavation of roots revealed parent root connections among P. grandidentata stems up to 50 years old. A number of dead stumps with live root systems, joined to living trees through the parent roots, existed on these exposed anastomotic networks. A tracer injected into donor stems in 119 P. grandidentata clones in 4 stands of varying ages allowed discovery of the root connections between the donor and any receptor stems. There were 105 receptor trees distributed among 71 aspen clones injected with eosin bluish dye, 48 receptors among 24 clones injected with sodium arsenite, and 17 among 24 clones injected with radioactive Rb86. Tracers indicated that P. grandidentata clones of sucker origin consist of a number of interconnected stem groups. The parent root connections among healthy trees aparrently do not decay. Tracer transport implied that transport of materials probably occurs among stems under natural conditions.