About Fraxinus quadrangulata Michx.
Fraxinus quadrangulata Michx., commonly called blue ash, is a medium-sized deciduous tree. It typically grows 10–25 m (33–82 ft) tall, with a trunk 50–100 cm (20–39 in) in diameter. Its twigs usually have four corky ridges, which give them a square appearance in cross-section. This feature is the source of the species name quadrangulata, which means four-angled. Blue ash has reddish-brown winter buds. Its leaves are 20–38 cm (7.9–15.0 in) long, and carry 5–11 leaflets, most often 7. Each leaflet is 7–13 cm (2.8–5.1 in) long and 2.5–5 cm (0.98–1.97 in) broad, with a coarsely serrated margin and short but distinct petiolules. The tree produces small purplish flowers in early spring, before leaves emerge. Its fruit is a samara 2.5–5 cm (0.98–1.97 in) long and 6–12 mm (0.24–0.47 in) broad, including the wing. The common name blue ash comes from a black dye that can be extracted from the tree's inner bark by immersing the bark in water. European colonists and American pioneers used this dye to color yarn for textiles, sewing, crocheting, knitting, weaving, and embroidery. Blue ash wood is used to make flooring, baseball bats, furniture, tool handles, crates, and barrels. The city of Blue Ash, Ohio, an inner suburb of Cincinnati, took its name from the blue ash trees that grew in the area; logs from these trees were used to construct many of the community's earliest buildings. Native North American ash tree species are a critical food source for North American frogs. Leaves that fall from these trees into temporary and permanent ponds, large puddles, and other water sources are particularly suitable food for developing tadpoles. Due to the emerald ash borer, species such as red maple are replacing native ash in North America, and these maples are far less suitable food for frogs. This replacement results in poor frog survival rates and smaller adult frog sizes. American ash varieties do not have high tannin levels, which makes their leaves good frog food but also leaves them not resistant to the ash borer. Ash varieties native to areas outside North America typically have much higher tannin levels and resist ash borer infestation. Maples and various non-native invasive trees that are replacing American ash in the North American ecosystem also typically have much higher leaf tannin levels. Compared to other North American ash varieties, blue ash has increased resistance to the ash borer; this may be due to blue ash having a higher tannin content. If higher tannin levels are the cause of its increased borer resistance, blue ash leaves would be less palatable for maturing frogs than the leaves of other North American ash varieties most threatened by the borer. Black ash, another North American native ash species, also provides important habitat and food for various other creatures native to North America.
