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 Japanese ash is a form of Manchurian ash growing naturally on the northern Japanese islands of Honshu and Hokkaido, as well as on Sakhalin Island. On the cool mountain slopes it tends to concentrate in moist sites at the edges of mires or along rivers, with conifer forest dominating drier sites. Highly valued for the attractive patterning of its timber, the Japanese ash has become rather rare in the wild because of over-exploitation.