Large yellow primrose is a low villous, basal-leaved annual with a leafless flowering stem and oblanceolate, deeply pinnatifid leaves that are 1-2 divided into lanceolate to ovate lobes in turn further lobed or toothed.  The large, showy, yellow flowers age to reddish-orange.  The sepals are reflexed, and the petals are about 3/4" long and quite deeply notched.  There are eight stamens and a four-part stigma, the lobes of which can be 1/4" long.  This primrose opens in the evening and remains open most of the following day.  It inhabits sandy hills, dune margins, dry plains and slopes of creosote bush scrub, joshua tree woodlands and pinyon-juniper woodlands in the Mojave and northern Colorado Deserts to an elevation of about 5000', and blooms from March to May.  These second picture was taken in the East Mojave National Preserve, the first and third near Eureka Dunes.

Click here for Latin name derivations: 1) Oenothera 2) primiveris 3) bufonis.
Pronunciation: ee-no-THEER-a pri-mi-VER-is boo-FO-nis.
Click here for Botanical Term Meanings.