Stems to 3 m; bark persistent, leathery. Leaves green; blade sharply 3-angled in cross section, widest proximal to middle, ad-axial side concave, outer angle serrate near apex, 5-11 × 1-1.5 cm. Inflorescences: pedicel 20-60 mm. Flowers 8-10 cm diam.; calyx lobes 10-60 mm; outer 2 lobes sharply 3-angled in cross section, abaxial angle serrate near apex, 30-60 mm; inner 3 lobes smaller, with membranous margins; petals (including petaloid staminodia) 100-200, yellow, aging pink, 2-4(-5)-seriate, 30-40 mm; stamens 100 per series, yellow, 4(-7)-seriate, simple to plumose, 6-8(-12) mm; anthers yellow; stigmas radiating out over fruits, 8-15 mm. Fruits yellowish, clavate to subglobose, depressed apically, 20-35 mm. Seeds ca. 1000. 2n = 18.