In this species of St. John's-wort, unlike the common St. John's-wort (H. perforatum), both the leaves and the flowers are dotted with black glands often appearing in streaks. Each flower is about ½ inch in diameter (smaller than many other related species) and has five yellow petals. They occur in tight clusters at the ends of stems. In the center of the flower is a flask-shaped pistil that is surrounded by numerous yellow anthers at the end of long filaments. There is no floral scent. The seedpods, when mature, split into 3 sections, exposing numerous tiny seeds. These are scattered by the wind when the stems sway back and forth.

The plant grows 1-3 feet tall in thickets and damp places. It is a native perennial plant that is found throughout central and eastern North America. The leaves are opposite and lack hairs. They are about 2 ½ inches long and 1 inch wide. There may be smaller leaves in the axils of the upper leaves. The underside of the leaves has scattered translucent dots. Small colonies of this species may form by the growth of underground rhizomes. The blooming period is June to September.