A rather inconspicuous flowering perennial, receiving its Latin name from Circe, the daughter of Sol and Perse, a mythical enchantress who first charmed her victims and then transformed them into various animals. The frequency with which it is encountered in shady woods makes this otherwise inconspicuous plant noteworthy. The upright stalk is covered with fine hairs, and grows from one to two feet in height. It is branching, and swollen at the joints. The slender stemmed leaves, which are arranged in opposite pairs, are pointed oval in shape with the edges faintly scalloped. The tiny, white flowers are set in a slender terminal spike. They have only two petals, which are heart-shaped, and alternate with two stamens. The tiny, two-parted calyx is hairy, and the small, drooping, pear-shaped fruit is densely covered with stiff, hooked hairs. This species is found from June to August, from Nova Scotia to Georgia, Nebraska, and Missouri.

A smaller species, C. alpina, has thin, somewhat shining leaves which are acutely pointed, slender-stemmed, coarsely toothed and, at the base, somewhat heart-shaped. The flowers are an inch broad and the long, oval seed case is covered with soft, hooked hairs. It is found in cool, moist woods from Labrador and Alaska southward to Georgia, Indiana, Michigan, and Minnesota. Also in Europe and Asia. It is found in blossom from July to September.