Flower:

Flowers are borne on feathery panicles, several inches across, from leaf axils of one year old branchlets. Male and female flowers occur on separate trees, both lacking petals, the minute calyx in four parts, the male typically with just two, often red or purplish stamens, the female with only a single style. Flowers emerge before the leaves in spring.

Leaves and bark:

Leaves are opposite and pinnately compound, 8 to 12 inches long with 5 to 9 (usually 7) oval to lance-elliptic leaflets. Leaflets are 2½ to 5 inches long and 1 to 2 inches wide with a distinct, ¼ to 1/3 inch, slender stalk, finely toothed edges, tapering to a pointed tip. The upper surface dark green and smooth, the lower surface pale green with short hairs along midvein and at the base of lateral veins.

Branchlets are often stout, smooth, green to brownish or even purplish colored with short, vertical white lenticels (pores) the first year. Branches turn brownish gray, the bark with blocky, diamond shaped ridges with deep furrows between them.

Fruit:

Fruit is a single, spatula shaped, winged seed (samara), 1 to 1¾ inch long and ¼ to 1/3 inch wide, in open dangling clusters that can persist on the tree all winter.

Notes:

White Ash is a large forest tree that grows over 100 feet tall and 32 inches in diameter at breast height in mesic deciduous forests in Minnesota's southeast and east central counties, and is the largest and least common of our three native ash species. While all three species are very similar, White Ash can easily be distinguished from the other two by the distinctly stalked leaflets. It is also the only ash to develop a fall color that ranges from deep purple to bright red. In winter, the dormant buds most closely resemble Green Ash (Fraxinus pennsylvanica) with chocolate brown buds and the two lateral buds tight against the terminal bud, but the leaf scars of the lateral buds of White Ash are deeply crescent shaped and narrower. As an urban tree, it has been less frequently planted than cultivars of Green Ash, but like them, all the selected cultivars are males and so will rarely be observed with pistillate flowers or seeds in urban plantings. Unfortunately, it is highly susceptible to the destructive emerald ash borer to which it and all ash in North America will likely eventually succumb.