Evening primrose, which does indeed flower as the sun goes down, played an interesting role in the study of genetics. Primrose chromosomes are unique for their ability to form circles rather than pairs, resulting in frequent and sudden mutations which defy Mendelian genetics. Though this flower may have baffled scientists of the past, we're charmed by the simple elegance of its flowers. The plant is also edible and has been used medicinally to aid with everything from coughs to pregnancy.