Jie geng plant is a perennial herb, 30 to 90 cm in height. The whole plant is glabrous. Roots are fleshy, cylindrical, and branched sometimes. Erect stems are single or branched. Leaves are nearly sessile. Leaves on the middle or the lower stems are opposite or in whorls of 3 to 4. Leaves on upper part of stem are sometimes alternate. Leaf blade is ovate-lanceolate, 3 to 6cm long, 1 to 2.5cm wide, and with acute apex, cuneate or rounded base, and serrate margin. Flower solitarily grows on the top the stem, or a few of them form sparsely racemes. Blue-purple calyx is campanulate. Capsule is obovate, with 5 valvular dehiscences on top when ripe. Seeds are ovoid and with 3 edges. Flower season is from July to September and fruiting phase is from August to October. Habitat in the wild is the hillside grass. Main chemical constituents are a variety of saponins, including 18 kinds of triterpenoid saponins like platycodin, deapioplatycodin, 2-O-acetylplatycodin, 3-O-acetylplatycodin, and so on.