Dasistoma macrophylla (Nutt.) Raf. is a photosynthetically competent hemiparasitic plant known to parasitize 21 different tree species. How different tree species vary in quality as hosts for this hemiparasite and how parasitism affects host growth have not been explored. We tested the hypothesis that D. macrophylla form more vascular connections, known as haustoria, to roots of the tree species that promotes greater growth of the hemiparasite in a greenhouse experiment. Juvenile Acer saccharum Marshall (sugar maple), a known host, and Quercus macrocarpa Michx. (bur oak), a previously untested species common to the locality, were grown alone or with one seedling of D. macrophylla derived from one of two populations. Additional D. macrophylla seedlings were grown alone. After 17 wk, dry shoot and root mass of the tree, dry shoot, and root mass of the hemiparasite, and the number of haustoria formed by the hemiparasite were determined. Dasistoma macrocarpa grew better with A. saccharum than it did with Q. macrocarpa. Growth of hemiparasites in the absence of a host was intermediate to growth with either tree. Consistent with greater growth on A. saccharum, D. macrocarpa formed significantly more haustoria on A. saccharum, and both shoot and root growth of maples was strongly reduced. The hemiparasite formed few connections with the bur oak, and shoot and root mass of Q. macrocarpa was unaffected by the parasitism. This study supported the hypothesis that tree species differ in quality as hosts, and D. macrophylla adversely affect valuable hosts.