It is a tall-growing plant, the stems, which are angular and often of a purplish hue, frequently rising 1m / 3ft or more in height. The leaves are smooth and of a dark green tint on the upper surface, but covered with a dense cottony down beneath; they are once or twice pinnately lobed, the segments being lanceshaped and pointed.

The flowers are in small oval heads with cottony involucres and are arranged in long, terminal panicles; they are either reddish or pale yellow. It usually flowers from July to September. The flowers are hermaphrodite. The Mugwort is closely allied to the Cornmon Wormwood, but may be readily distinguished by the leaves being white on the under-surfaces only and by the leaf segments being pointed, not blunt. It lacks the essential oil of the Wormwood.