Herb, stem erect, simple or branched, sometimes not higher than 40 cm, or plant scandent or climbing, up to several meters long. Leaves alternate, sometimes opposite or verticillate and clustered, sometimes clustered above the middle of the stem, sessile, base sometimes sheathing the stem, ranging from linear, elliptic-lanceolate, elliptic to ovate, 6-17.5 cm long, 0.4-5 cm wide, apex acute, acuminate, falcate or ending in a tendril. Flowers solitary, axillary, sometimes terminal, different shades of yellow, orange, red, crimson, purple/mauve stripes or fading purple, often bicolored; pedicel erect, recurved apically, 3.5-18 cm long. Perianth sometimes at the base connate into a short tube, up to 2 mm long; perianth segments (strongly) reflexed, base clawed, narrowly elliptic-linear, oblong-lanceolate, sometimes ovate to obovate, 29-85 mm long, 4-25 ( -38) mm wide, the margins sometimes crisped, apex acuminate to acute, sometimes falcate. Filaments filiform, sometimes flattened, 10-45 mm long; anthers straight to curved, 5.5-15 mm long. Ovary 4-13 mm long, 1-5 mm wide; style 9-50 mm long. Capsule 37-50 mm long, 10-14 mm in diameter; seeds 4 mm.