Narrow-leafed Ash, Fresno de hojas estrechas

It is a medium-sized deciduous tree growing to 20–30 m tall with a trunk up to 1.5 m diameter. The bark is smooth and pale grey on young trees, becoming square-cracked and knobbly on old trees. The buds are pale brown, which readily distinguishes it from the related Fraxinus excelsior (black buds) even in winter. The leaves are in opposite pairs or whorls of three, pinnate, 15–25 cm long, with 3-13 leaflets; the leaflets being distinctively slender, 3–8 cm long and 1-1.5 cm broad. The flowers are produced in inflorescences which can be male, hermaphrodite or mixed male and hermaphrodite. The male and hermaphrodite flowers occur on all individuals, i.e. all trees are functionally hermaphrodite. Flowering occurs in early spring. The fruit when fully formed is a samara 3–4 cm long, the seed 1.5–2 cm long with a pale brown wing 1.5–2 cm long.