Hartweg's evening-primrose, Oenothera hartwegii

Hartweg's is another of the many evening-primroses one can see going west. This one has flowers a little larger than most - up to about three inches across. Many experts would call this Calylophus hartwegii. Note the roundish stigma, it's just below the edge of the flower at the upper middle. Those experts divide Calylophus from Oenothera because of it. Their Oenothera have distinctly four-lobed stigmas. Apparently, even genome analysis does not make it easy to decide where to draw lines between genera. Hartweg's grows in AZ, CO, KS, NM, OK, and TX. Sedgwick Co CO, 6/16/13. Willowherb family, Onagraceae.