This introduced plant is a summer annual about 3-6' tall; it is more or less erect and branches regularly. The light green stems are angular-terete, ridged, and hairless; the secondary stems are ascending or spreading. The alternate leaves are up to 6" long and 4" across, becoming smaller as they ascend the stems. They are green and hairless. Each leaf is pinnately divided (double or triple) into slender lobes that are narrowly lanceolate or oblong-lanceolate; some of these lobes are cleft or toothed along their margins. The lower leaves have petioles, while the upper leaves are sessile. The upper stems terminate in floral panicles up to 1½' long and half as much across. The panicles are abundantly branched, each branch consisting of a raceme of small drooping flowerheads. about 1-2 mm. across (1/8" or less). Each flowerhead is about 2 mm. across (1/8" or less); it has many tiny disk florets. At the base of each flowerhead, there are 6 oblong bracts that are dark green. The blooming period occurs from late summer into the fall. There is no floral scent, although the foliage has a sweet fruity fragrance. Pollination is by wind. Upon maturity, each floret is replaced by a single achene. These achenes are small enough to be carried aloft by the wind, even though they lack tufts of hair. The root system consists of a branching taproot. This plant reproduces by reseeding itself.