The Manchurian ash resembles the native Finnish species, the European ash (F. excelsior), but its leaves are considerably larger and the shoots thicker; as if painted with a broader brush. The previous year’s shoots are bluntly angular. The wind-pollinated flowers appear before leaf flush and are polygamous, i.e. each tree can have flowers with male and female organs, or flowers which are only male or female, or any combination of any or all of these.
The large leaves are very similar to those of the North American black ash (F. nigra) and some botanists consider these two to be related subspecies. In the wild Manchurian ash grows in sparse mountain slope forests and open river valley groves in East Asia. It is naturally adapted to a continental climate, which makes it frost-hardier than Finland’s native ash, but at the same time much more susceptible to late spring frosts. This means that in Finland it is best suited to sheltered sites in eastern parts of the country.