Arceuthobium laricis

Arceuthobium laricis, commonly known as larch dwarf mistletoe, is a species of flowering plant in the family Santalaceae. As with other species of dwarf mistletoe, A. laricis parasitizes several species of conifers, especially the western larch and mountain hemlock. Its geographic range largely coincides with the range of the western larch through the Pacific Northwest. A. laricis significantly impacts the ecology of conifer forests where it occurs. Mistletoe infections decrease the vitality and reproductive rate of host trees, often leading to tree death. They induce the formation of witch's brooms on host trees, which serve as important microhabitats for wildlife and increase available fuel for wildfires. The species is also an important food source for birds and insects and is itself parasitized by two species of fungi. Since its formal description by Charles Piper, taxonomists have placed A. laricis under several names. Its taxonomy is still debated, with some authorities treating it as a subspecies of Arceuthobium campylopodum and others maintaining it as a distinct species.

from Wikipedia