A deciduous tree 20-35 m tall, and is readily distinguished from other species of ash in that it has black buds, unlike the brown buds of most other ashes. The leaves are 20-35 cm long, pinnate compound, with 9-13 leaflets. The flowers open before the leaves, the female flowers being somewhat longer than the male flowers; they are dark purple, and without petals. The female flowers develop into fruits, and because they hang in bunches the fruits of the ash tree are known as 'ash keys'.
In the treatment of intermittent fever and ague, to remove obstructions of the liver and spleen, and in rheumatism of an arthritic nature; to cure scabby and leprous heads (ashes of bark).