FAMILY: Onagraceae — Evening Primrose family
OTHER COMMON NAMES: Spring evening primrose, Desert evening primrose
ETYMOLOGY: The Greek roots of the name of the genus Oenothera are disputed, but in Latin, the word refers to a soporific (sleep-inducing) plant.
The species epithet primiveris means 'truly the first', a reference to the plant's early spring flowering.
DESCRIPTION: The four delicate heart-shaped petals of the yellow primrose flower open at dusk and close in the morning. Flowers will last well into the morning if it is cool. It is a spring annual with a blooming period that begins in February. Prostrate rosettes grow individually. The green to greenish-gray many-lobed leaves can grwo to a length of four inches. It is believed the hawk moth pollinates the flower because it has a tongue long enough to reach the nectar at the base of the slender floral tube. While gathering nectar, the fuzzy body of the moth picks up the long sticky pollen threads characteristic of the yellow primrose and transfers it to other plants.
The yellow primrose is found in desert washes and arroyos below elevations of 4,500'.