Great Basin Naturalist


A second small population of white fir dwarf mistletoe, Arceuthobium abietinum f. sp. concoloris, is reported from the Santa Catalina Mountains in southern Arizona. The discovery of a second population of this mistletoe in southern Arizona supports the contention that it once had a more southern distribution but has survived past climatic changes in only a few locations in the southwestern United States. The distribution of the Western spruce dwarf mistletoe, Arceuthobium microcarpum, is extended to the Sacramento Mountains of south central New Mexico, a range extension of approximately 170 miles. The mistletoe is restricted to an area of about 300 acres, but its potential for further spread is high. The possible implications of this range extension to the biosystematics of Picea spp. and the evolution of A. microcarpum are discussed.