Betula uber Betula uber Betula uber, Virginia round-leaf birch, is a rare species of tree in the birch family. One of the most endangered species of North American trees, it is endemic to Smyth County, in the U.S. state of Virginia. It is part of the temperate broadleaf and mixed forests biome. The tree was first described in 1918 as a variety of "Betula lenta", and elevated to species status in 1945. It hybridizes with "B. lenta" and it has been suggested that it is actually a round-leaved mutant form of "B. lenta". Some authorities prefer to treat it as a variety.
Northern celestial hemisphere Northern celestial hemisphere The northern celestial hemisphere, also called the Northern Sky, is the northern half of the celestial sphere; that is, it lies north of the celestial equator. This arbitrary sphere appears to rotate westward around a polar axis due to Earth's rotation. At any given time, the entire Northern Sky is visible from the geographic North Pole, while less of this hemisphere is visible the further south the observer is located. The southern counterpart is the southern celestial hemisphere. In the context of astronomical discussions or writing about celestial cartography, this celestial hemisphere may also simply then be