Perennial, erect or climbing herb; rootstock tuberous, stem terete, glabrous; leaves sessile or shortly petioled, scattered, opposite or 3-nately whorled, ovate-lanceolate, nerves many, entire, glabrous, tip, often ending into a tendril; flowers large, showy, solitary or in subcorymbose racemes; pedicels reflexed; perianth persistent, bright yellow to orange in lower half, red in upper half, finally red with age, segments-6, subequal, oblong-oblanceolate, spreading or reflexed, undulate on margins, stamens 6, filaments exserted, slightly curved, dark purple to red, anthers oblong or linear, extrorse, versatile; ovary 3-celled, style long, filiform, deflexed, arms shortly trifid, introrsely stigmatose; capsules large, coriaceous, 3-valved, loculicidal, ellipsoid or fusiform, dark green; seeds subglobose, angular, numerous, black.