Northern Prairie Wildlife Research Center
OLIVE FAMILY (Oleaceae)
IND. STATUS: FACW+
FIELD CHARACTERISTICS: A deciduous tree growing to 25 m. in height. The leaves are opposite and compound. Leaflets number 7-11 and are 5-6.4 cm. long, toothed, and sessile. Leaf scars are nearly circular. Branches are circular, or nearly so, and smooth. The bark is furrowed to scaly. Fruit is a flat samara, winged to the base and blunt on both ends. In flower during April and May.
The circular (or nearly so) branches distinguish F. nigra from the 4-sided branches of blue ash (F. quadrangulata). The nearly circular leaf scars, sessile leaflets, and flat samaras winged to the base of F. nigra distinguish it from the half circle leaf scars, slightly petioled leaflets and wedge-shaped samaras with a flat wing of green ash (F. pennsylvanica).
ECOLOGICAL NOTES: Black ash is typically found in wooded swamps.
SOURCE: Gleason and Cronquist (1991); Petrides (1972); and Swink and Wilhelm (1994).