Oleaceae: Fraxinus pennsylvanica
Green ash has been planted in windbreaks and urban plantings throughout SD and is an excellent shade tree. Unfortunately, it is under attack by the emerald ash borer and must be closely monitored and treated or it will be killed within 3 years after being infested by the bug.
Description
Fraxinus pennsylvanica is a large tree reaching 20 m tall with dark gray to brown, furrowed bark. The younger branches go from greenish with white lenticels (pores) to brown to gray and can be smooth to hairy. The petiolate, opposite leaves are compound odd-pinnate,11-30 cm long, with 5-9 leaflets. The leaflets are lanceolate to elliptic, 6-15 cm long and up to 5 cm wide, with short stalks. The first pair of leaflets is usually the shortest. The margins usually have small teeth, the upper surface is dark green and smooth and the lower surface is paler with short hairs along the midvein or across entire surface. The trees are dioecious, having either male or female flowers. The inflorescences consist of panicles, 3-5 cm long, in the axils of leaves on the first year branches. The flowers have an irregularly toothed, cup-shaped calyx, no petals and either 2-3 stamens or a pistil with a long style. The fruit is a tan, narrowly oblanceolate single samara. Green ash blooms in April and May in flood plains, ravines and along stream and lake shores throughout South Dakota.
