Fraser fir this purpose. Fraser fir has been used more times as the White House Christmas tree (the official Christmas tree of the President of the United States's White House) than any other tree. It is grown in plantations in Scotland and sold by the thousands throughout the United Kingdom and Ireland. It is also cultivated from seedlings in several northern states in the USA and adjacent parts of Quebec province, especially for the Christmas tree trade. The combination of form, needle retention, dark blue-green color, pleasant scent and excellent shipping characteristics has led to Fraser fir being a most popular Christmas
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