A summer annual reaching 0.2-2 m tall producing a conspicuous prickly bur fruit in the late summer and fall. First true leaves are opposite, subsequent leaves are alternate. Three prominent main veins are evident on upper surface.
First leaves are opposite, subsequent leaves are alternate.
Two prickles that are longer and wider than the remaining prickles project from the tip of the bur. Erect, branched, stout and covered with a dense cover of short stiff ascending hairs and 'bumps'. Stems are ridged longitudinally and green with maroon to black spots. Freely branched stout taproot. Stems with maroon to black stem lesions.