Oenothera
laciniata
Cut-leaved
primrose
Onagraceae
Interesting info and more photos: missouriplants.com
Dan Teglia reports, "The flowers of this species open at night and close when hit by strong sunlight."
Dan Teglia - missouriplants.com
Dan Teglia - missouriplants.com
You ought to know:
Area: dry
Height: 1-5 feet
Frequency at ML: low
Blooms: Late Spring