A twining vine that grows to heights of 60–200 cm. The glossy, dark green leaves grow opposite on the stem and are ovate to elliptical. The flowers appear near the top of the plant and grow on stalks that come from the leaf axils. Each stalk has 5 to 20 flowers. The flowers are dark purple or dark brown. After a year of growth, the stem turns light brown and resembles a decaying stem and stops growing, yet it remains to cling onto the plant. The plant spreads its seeds by wind dispersal.