The grey-black rough bark is distinctively split into neat rectangles. The catkin-like flowers appear in early spring before the leaves.
Male and female flowers are borne separately on the same tree (monoecious). The small 3-lobed capsules or schizocarps split into three equal indehiscent segments (mericarps or cocci) when ripe; on a warm day this splitting (dehiscence) can sound like a distant fusillade of shots.