The dogbane/milkweed family includes annual plants, perennial herbs, stem succulents, woody shrubs, trees, or vines. Most exude a milky sap with latex, if injured. Leaves are (simple). Leaves may appear one at a time (singly) with each occurrence on alternating sides of the stem (alternate), but usually occur in pairs or in whorls. When paired, they occur on opposite sides of the stem (opposite), with each pair occurring at an angle rotated 90° to the pair below it (decussate). There is no stipule (a small leaf-like structure at the base of the leaf stem), or stipules are small and sometimes fingerlike. (Learn how and when to remove this template message) Flowers have radial symmetry (actinomorphic), and are borne in heads that are cymes or racemes, but are rarely fasciculate or solitary. They are perfect (bisexual), with a synsepalous, five-lobed calyx united into a tube at the base. Inflorescences are terminal or axillary. Five petals are united into a tube with four or five epipetalous stamens. The style is expanded at the apex into a massive clavuncle just below the stigma. The ovary is usually superior, bicarpellary, and apocarpous, with a common fused style and stigma. The fruit is a drupe, a berry, a capsule, or a follicle.