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.