Petty spurge
Euphorbia (=Chamaesyce) peplus

Petty spurge is a hairless, erect, light green plant, with single or branched slender stems that can grow to almost 20 inches (0.5 m) tall. Lower leaves are egg shaped, with a rounded to a slighted indented tip, 2/5 to 1-2/5 inches (1–3.5 cm) long, on a short stalk, and are either alternate to one another or almost opposite to one another with one leaf in each pair attaching a little below the other. Reduced leaves (bracts) are opposite to one another along the flowering portion of the stem. A whitish sap exudes when stems are broken.
Flowers bloom from February through August. Tiny, greenish-yellow, non-showy flowers are grouped in small flowerlike cups and surrounded by crescent-shaped glands with tiny horns at each end.
Fruits consist of tiny three-lobed capsules, 1/17 to 1/10 of an inch (1.5–3 mm) in diameter, hairless, and nearly round. Each capsule contains three seeds.