Description of Oenothera sect. Gauropsis:
Distribution: Oenothera canescens is restricted to prairie depressions, playas, ditch margins, and other places of temporary water in the High Plains of the western United States from southeastern Wyoming and western Nebraska south through eastern Colorado and New Mexico, western Kansas and the Texas Panhandle, with disjunct populations in Stafford, Sedgwick, and Chautauqua counties, Kansas; from 430 to 1,700 m elevation.
Habit: Leafy, bushy to sprawling or compact perennial herbs, spreading by adventitious shoots from lateral roots; stems simple to branched, decumbent to ascending.
Leaves: Leaves not forming a basal rosette (at least not after stems elongate), (0.3-) 0.6-2.5 cm long, lanceolate to linear, sinuate-denticulate to subentire.
Flowers: Buds erect, terete in cross section, without free tips or free tips minute, floral tube 8-17 mm long, scarcely flaring at mouth, sepals splitting along one suture, remaining coherent and reflexed as a unit at anthesis or rarely separating in pairs, petals pink, rarely white, streaked or flecked with red, fading bright purple.
Fruit: Capsule woody, ovoid, constricted to a sterile beak, the valves with narrow wings 1-1.5 mm wide, indehiscent.
Seeds: Seeds 50-100 per capsule, in 2-4 irregular rows, asymmetrically cuneiform, angled, glossy, obscurely reticulate, appearing finely granular.
Chromosomes: Chromosome number: n = 7.