Onagraceae: Evening-primrose Family — Suncups & Primroses
All members of the Evening-Primrose family have 4-petaled flowers, and many of them are showy. Despite the name, they do not necessarily bloom in the evening. There is a separate family called Primrose (Primulaceae).
This page includes two genera, Camissonia and Camissoniopsis, which used to be treated as one genus but have now been separated. There are three differences between them. Camissonia has more or less straight fruits, cauline leaves only, and its flowers are on the uppermost nodes; while Camissoniopsis generally has coiled fruits, basal and cauline leaves, and its flowers are on nodes along the whole stem. Individual members of these two families can be extremely hard to distinguish. Pay careful attention to the types of hairs, possible presence of glands, and possible presence of small red spots at the base of the petals.