For the differences with C. parnassifolia see the key. Leaves broader than long, suborbicular, base truncate, apex emarginate, measured along the midrib 11 cm, width 14 cm; nerves 13-17; petiole septate. Sepals 4-5 by 2.5 mm. Stamens 9(-11, cf. SAMUELSSON). Carpels (12-)17(-20); style 2.5 mm; achenes not seen.