Herbaceous plants and shrubs; leaves alternate on the stem, either simple or divided; without stipules at the base of the leaf-stalk. The flower-stalks are generally long, bearing flowers singly; the calyx is composed of only two or three sepals, which fall off when the flower expands; the petals are usually four, sometimes six,—in Bocconia they are wanting. In the bud state the petals are usually crumpled. Stamens numerous, attached to the base of the pistil, the style of which is short; stigmas, either two or many, forming a rayed star on the top of the ovary. The seed-vessel is either a capsule as in the Poppy, or long and pod-shaped as in Glaucium, the Horn Poppy, containing numerous seeds of a fleshy, oily nature.