This is the stem of the Chinese green cow gall, a plant in the family of Antigua and Barbuda.

The Chinese green ox gall is a deciduous woody vine, 3-10 meters long. Young branches are pilose, old branches are glabrous, with many lenticels. Leaves alternate; broadly ovate to circular-ovate, 7 to 12 centimeters long, 5 to 10 centimeters wide, apex cuspidate, base cordate, hispidulous above, tomentose below, basal veins 5 to 7; petiole 4 to 10 centimeters long, pilose. Racemes axillary, opening before leaves; unisexual; flowers yellowish. Infructescence ca. 10 cm, drupe bright red, endocarp semiovoid, 8-10 mm long, ventral surface flat, abaxial surface with ribbed ridges and numerous small warty projections. Seeds ca. 5 mm, hemispherical, ventral surface sunken. Flowering period March to April. Fruiting July-August. Born in forests.

But herbal medicine is still a lot of long like, if you are not very sure, it is still recommended to ask a doctor, to be on the safe side.