Mature plant. Spotted spurge generally has prostrate stems that can grow up to about 20 inches (50 cm) in length, but stems can grow upward when competing for light with other plants. Branches alternate along the stem. New leaves are typically hairy, especially lower leaf surfaces. Leaves are oblong to egg shaped, about 1/6 to 2/3 of an inch (4–17 mm) long, often marked with a characteristic dark, reddish spot found midway down the center of the leaf vein, and sit atop short stalks. Creeping spurge, C. serpens, leaves are not marked with a characteristic spot. When broken, a milky, sticky sap oozes from the stem.
Flowers. Flowering takes place from May through October. Tiny, inconspicuous flowers are grouped in small flowerlike cups and are surrounded by white to pink petal-like appendages. Flower clusters are found at the stem tips and along the length of the stem, where one to two small flower clusters are produced where the stem and leaf stalk meet (leaf axil).
Fruits. The fruit consists of a tiny, roughly 1/17 of an inch (1.5 mm) long, evenly hairy, egg-shaped capsule with three lobes. The creeping spurge fruit capsule is similar in size but it is hairless and roundish.