Distribution: From southern Texas, USA, through northern Mexico to the Trans-Volcanic Belt of central Mexico, southward to Guatemala, Nicaragua, and Costa Rica, in openings in pine-oak or conifer forests on slopes or along streams (or arroyos), sometimes along roadsides or other weedy habitats, from 1400 to 2800 (-3250) m elevation. Presumably escaped from cultivation and has become naturalized in Colombia, Venezuela, Argentina, Bolivia, Ecuador, Jamaica, South Africa, Australia, Asia, and Europe.
Habit: Plant a perennial or annual, from a slender taproot, strigillose and also hirsute. Stems several or sometimes more, decumbent to ascending, usually branching, 15-50 cm.
Leaves: Leaves in a basal rosette and cauline, 2.5-10 x 0.6-2.5 cm; petiole 0.2-2.2 cm; blade lanceolate to oblanceolate, occasionally elliptic, margin weakly serrate to sinuate-pinnatifid.
Flowers: Inflorescences of flowers erect in axils of upper leaves. Flowers with buds erect, terete in cross section, 1-3 opening near sunset, with free tips 0.5-3 mm; floral tube 10-30 mm, flaring at apex; sepals 20-40 mm, splitting along one suture, remaining coherent and reflexed as a unit at anthesis or rarely separating in pairs; petals 20-38 mm, white, fading pink; staminal filaments 12-18 mm, without appendage at base; anthers 5-10 mm, pollen 85-100% fertile; style 19-67 mm long, stigma deeply divided into 4 linear lobes and elevated above the anthers at anthesis.
Fruit: Capsule hard and leathery, proximal part sterile, cylindrical, tapering to the base, body 7-20 x 6-7 mm, obovoid or rarely broadly clavate, the distal part of each valve with a rib, wings 2-3 mm, stipe slender, 5-45 mm.
Seeds: Seeds numerous, clustered in each locule, narrowly obovoid, the surface glossy, appearing granular, but minutely papillose under magnification, 1-1.5 x 0.5-0.7 mm.
Chromosomes: Gametic chromosome number, n = 7 (forming 7 pairs at meiotic metaphase I).
Contributor: Nancy Khan