Blue ash (Fraxinus quadrangulata) is a member of the Oleaceae or olive family which is a large family found in the temperate and tropical forests of the North Hemisphere. There are approximately 16 species in the Fraxinus or ash genus native to the United States and only 5 may attain commercial size and abundance. Blue ash is a medium sized tree that typically grows 70 feet tall and18 to 40 inches in diameter. It is a moderately slow-growing tree and can live up to 300 years but typically lives 150 to 200 years.