Madworts are smaller annual to perennial herbs, short-hairy with star-shaped hairs. The leaves on our species are simple and entire. The plants have many small flowers in elongate, narrow, bractless clusters. The 4 petals are yellowish, or in ours often more nearly cream and fading to white. There are 6 stamens, the 2 shorter ones flanked by linear glands about 1 mm long. The anthers are oval. The style is very short. The fruit pods are almost round to ovate-elliptic, less than twice as long as broad, strongly compressed, notched at the tips, the valves nerveless, with 1-2 seeds in our species.
The nearly 100 species of the genus are almost entirely Eurasian, but several are introduced as ornamentals or weeds in N. America. The word Alyssum comes from the Greek a, not or without, and lyssa, madness - the plant supposedly was believed to have value in allaying anger, madness, or hydrophobia.