Fraxinus pennsylvanica Marsh.

Green ash is a medium sized tree that rarely attains heights over 20 meters (approx. 60 feet). The bark is thick, deeply furrowed, alternating with firm ridges in mature trees, but otherwise not a distinguishing, diagnostic characteristic. Distinctive features are opposite, pinnately (feather-shaped) compound leaves and narrow-winged, dry fruits called samaras (1 2 cm long and 3 5mm wide). Only one other native tree species has opposite, pinnately compound leaves in Eastern North America and that is ash-leaved-maple or box elder (Acer negundo). The two species are easily differentiated by examining the following characteristics: 1) Box elder has 3 5 pinna (leaflets) per compound leaf and F. pennsylvanica has 5 7 pinna (usually 7) per leaf; 2) Each pinna of A. negundo is usually 3 pointed and somewhat lobed, whereas green ash rarely has obviously toothed margins; and 3) Box elder produces a double winged fruit (samara), typical of maples, while ashes have single samaras. The angular, flattened samaras of ashes are diagnostic characteristics. The only other trees with opposite compound leaves are the buckeyes (Aesculus spp.), but their pinna are palmately arranged, as the spokes of a wheel.