Fraxinus pennsylvanica is a tree to 25 m tall; about 100 years, fast growing; shallow rooted; bark flaky, buds brownish, terminal bud pointed, higher than wide, top of leaf scar with little or no notch, new growth often finely hairy.
Leaves opposite, pinnately compound, leaflets 5-9, usually 7, lance to egg-shaped, margin more-or-less toothed, underside not finely warty but often finely hairy, both sides green, base extending down short leaflet stalk, leaf axis slightly winged.
Flowers with sexes on separate plants (dioecious), small, wind pollinated, males flower before females, April-May.
Fruit winged half way to base of seed, wing shorter than body of seed, body of seed 0.2 cm wide. Wind dispersed, Oct. into winter over short distances. Seeds will not germinate before overwintering at least once. Seeds eaten by a few birds and small mammals.
Wetland status: FACW.
Frequency in New York City: Frequent.
Habitat: Moist woods to swamp forests in fertile soil. Common pioneer on wet soil. moist to wet soil, pH 4.7-8.1 (USDA, NRCS 2010). Tolerates flooding or saturated soil up to 75% of growing season; drought tolerant, develops adventitious roots when stem submerged, increases anaerobic respiration and transports oxygen to root system. Intolerant of shade, index 2-4. Moderately salt tolerant. Tolerates soil compaction (Hightshoe 1988).
Notes: Host to the emerald ash borer (Agrilus planipennis) which has become widespread and a major threat to our populations of Fraxinus (see F. americana). Subject to damage from oystershell scale (Lepidosaphes ulmi). Various insects cause damage, which allows entrance of fungal infections (Burns and Honkala 1990). Susceptible to ash “yellows” (see F. americana, Pokorny and Sinclair 2001). Twigs eaten by deer. Rabbits eat seedlings (Martin et al. 1951). A host tree of the Asian longhorn beetle, Anoplophora glabripennis (see Norway maple).