Description from Flora of China
Nyctago jalapa (Linnaeus) Candolle.
Herbs annual, to 1 m tall. Roots tuberous, black or black-brown. Stems erect, much branched, cylindric, glabrous or slightly pubescent, inflated on nodes. Petiole 1-4 cm; leaf blade ovate or ovate-triangular, 3-15 × 2-9 cm, base truncate or cordate, margin entire, apex acuminate. Flowers usually several clustered at apex of branches, fragrant; pedicel 1-2 mm. Invo- lucre campanulate, ca. 1 cm, 5-lobed, lobes triangular-ovate, acuminate, glabrous, persistent. Perianth purple, red, yellow, white, or variegated; tube 2-6 cm; limb 2.5-3 cm in diam., opening in late afternoon, closing next morning. Stamens 5; filaments slender, exserted; anther globose. Fruit black, globose, 5-8 mm in diam., coriaceous, ribbed and plicate. Endosperm white mealy. Fl. Jun-Oct, fr. Aug-Nov.
This species is used medicinally and as an ornamental.
Originally introduced as an ornamental, now a ruderal weed in some areas of China [native to tropical America; now pantropical].