Sundrops
Oenothera hartwegii (Calylophus hartwegii)

Family: Evening Primrose (Onagreaceae)
AKA: Hartweg's Sundrops
Photo taken on: May 19, 2009
Location: White Rock, NM
Life Zones: Plains to foothills
Habitat: Dry rocky slopes, roadsides

A low spreading plant growing to 18". Flowers look like Yellow Evening Primrose but they bloom during the day and the sepals have red blotches.

Flora of North America reference.