Douglas fir Douglas-fir forest is the primary habitat of the red tree vole ("Arborimus longicaudus") and the spotted owl ("Strix occidentalis"). Home range requirements for breeding pairs of spotted owls are at least 400 ha () of old growth. Red tree voles may also be found in immature forests if Douglas-fir is a significant component. The red vole nests almost exclusively in the foliage of the trees, typically above the ground, and its diet consists chiefly of Douglas-fir needles. A parasitic plant sometimes utilizing "P. menziesii" is Douglas-fir dwarf mistletoe ("Arceuthobium douglasii"). The leaves are also used by the woolly conifer aphid
Noble polyhedron 'dual' covers both kinds. The dual of a noble polyhedron is also noble. Many are also self-dual: Noble polyhedron A noble polyhedron is one which is isohedral (all faces the same) and isogonal (all vertices the same). They were first studied in any depth by Hess and Bruckner in late 19th century, and later by Grünbaum. There are four main classes of noble polyhedra: If we allow some of Grünbaum's stranger constructions as polyhedra, then we have two more infinite series of toroids: We can distinguish between dual structural forms (topologies) on the one hand, and dual geometrical arrangements when