"So much has already been written on this genus [Arceuthobium] of the Loranthaceae that many readers will no doubt be surprised that there should be anything new to be said on the subject" (Johnson 1888). However, since then there have been more than 4,200 publications involving Arceuthobium! Following the appearance of our monograph—Biology and Classification of Dwarf Mistletoes (Arceuthobium)—in 1972, over 2,200 publications concerning the group have appeared and 18 new taxa have been described. The dwarf mistletoes also have been the subject of two symposia: "Control Through Forest Management" in Berkeley, California (Scharpf and Parmeter 1978), and "Dwarf Mistletoe Biology" in Fort Collins, Colorado (Hawksworth and Scharpf 1984).
Because our 1972 monograph is out of print, and because of significant new research on the genus, we decided that a completely new publication was in order. This new study not only expands the topics covered in the earlier version, but it also includes several new aspects: reproductive biology, host-parasite physiology, ecological relationships, biotic associates, pathological effects on host trees, and control. Dr. Brian W. Geils contributed to the chapter "Biotic Associates" (chapter 8). Drs. Clyde L. Calvin and Carol A. Wilson, Portland State University and University of California, Berkeley, have contributed two chapters: "Anatomy of the Dwarf Mistletoe Shoot System" (chapter 10) and "Endophytic System of Arceuthobium" (chapter 11). Dr. Daniel L. Nickrent, Southern Illinois University, contributed the chapter "Molecular Systematics" (chapter 15).