Glabrous, twining perennial. Leaves ovate to lanceolate, 4–10 cm long, 2–8 cm wide, apex acuminate, base sagittate to hastate, margins undulate, basal lobes entire to shallowly lobed; petiole 1.5–5 cm long. Flowers with peduncles 3–12 cm long, much longer than petioles; bracteoles ovate, 1.5–2 cm long, apex acute, longer than and enclosing calyx, overlapping only toward base; sepals to c. 1.5 cm long; corolla 4–6 cm long, white or pinkish. Capsule ovoid to subglobose, 7–8 mm long. Flowers spring and summer.
Some Victorian collections are somewhat intermediate between C. sepium and C. silvatica. A similar situation has been noted in New Zealand (Ogden 1978) where intermediates have been thought to be the product of hybridisation and introgression.
