A deep-rooted perennial. Leaves are bluish-green and usually alternate, except those immediately beneath the flowers, which are whorled. Two kinds of leaves appear on the stem: leaves on the lower half of the stem are scalelike, while those on the upper parts are linear to oblong. All parts of the plant bleed a milky sap, which causes skin irritation. Foliage on early spring seedlings may be deep red or purplish. Blooms May through October. Flowers are borne in umbels and appear greenish-yellow. Each umbel supports 7-10 groups of tiny, inconspicuous flowers, subtended by 4 crescent glands and 2 conspicuous, greenish-yellow bracts.