Description of Oenothera sect. Xanthocoryne:
Distribution: This section consists of three montane species (four taxa) that occur from central Mexico through Central America to northern South America, in openings in shrublands and forests, in pastures, roadsides, or páramo, from 1,500 to 4,300 m elevation.
Habit: Perennial herbs from a taproot; stems usually several or more, decumbent or ascending, branched.
Leaves: Leaves in a basal rosette and cauline, the cauline leaf blades 1-5 cm long, elliptic to narrowly elliptic or lanceolate, not lobed toward the base, margins serrulate to subentire.
Flowers: Buds erect, terete in cross section, without free tips, floral tube 0.3-1.7 cm long, flaring at apex, sepals splitting along one suture, remaining coherent and reflexed as a unit at anthesis or rarely separating in pairs, petals yellow or with red in proximal half, fading red.
Fruit: Capsule with the proximal part sterile (in O. multicaulis the proximal part with one row of seeds per locule), hollow and cylindrical, the body clavate to narrowly ellipsoid, the valves angled or rarely with a narrow wing 0.5-2 mm, the distal part of each valve with a rib, apex abruptly tapering to obtuse tip.
Seeds: Seeds clustered in each locule, narrowly obovoid, the surface glossy, appearing granular, but minutely papillose under magnification.
Chromosomes: Chromosome number: n = 7 (in O. multicaulis (14).