Arceuthobium monticola is a species of dwarf mistletoe known as western white pine dwarf mistletoe. It is endemic to the Klamath Mountains of northern California and southern Oregon, where it lives as a parasite on western white pine trees. This is a brownish to reddish shrub which is visible as a network of scaly stems extending above the bark of its host tree. Most of the mistletoe is located inside the host tree, attached to it via haustoria, which tap the tree for water and nutrients. The leaves of the mistletoe are reduced to scales on its surface.