A twiner. Stem 0.3-0.4 cm or more in diameter, exuding milky sap, lenticillate and finely striated, glabrous; nodes distinct; internodes up to 29 cm or more in length; outer bark variegated grayish brown, cream and light green; inner bark light brown. Sometimes young, slender, leafless twigs can be found arising from the nodes. Leaves opposite, simple, exstipulate, entire, elliptic, apex acuminate-cuspidate, base obtuse; blade 13.5-23 cm long, 6.5-10.2 cm broad; glabrous; petiole 2.9-3.5 cm ling, 0.1-0.2 mm in diameter, sometimes twining; venation pinnately netted, brochidodromous with 8-10 pairs of lateral nerves. Inflorescence in peduncled cymes. Flowers  pentamerous, calyx with basal glands, deeply divided; corolla salver-shaped with short tube, hairy at the top, petals in bud overlapping to the right; stamens about the middle of the tube; filaments straight, connate, 0.35-0.38 cm long, strongly intertwisted, hairy; anthers oblong, partially exserted, adhering to the stigma, sagittate; disk 5-lobed, free, oblong to elliptic ,acuminate to apiculate; ovary 1, glabrous, 2-celled; cells many-ovuled; style glabrous, collared below stigma or at the base of it. Fruits a linear follicle, minutely puberulent.