Oenothera caespitosa, known commonly as tufted evening primrose, desert evening primrose, rock-rose evening primrose, or fragrant evening primrose, is a perennial plant of the genus Oenothera native to much of western and central North America. It produces a rosette of lobed or toothed leaves each up to 36 centimeters long around a woody caudex. It is normally night-blooming.
Epilobium obcordatum is a species of perennial plant in the evening-primrose family (Onagraceae), known by the common name rockfringe willowherb and rock fringe. It is native to the western United States from California to Idaho, where it is found in rocky mountainous areas, at altitudes of 7,000 ft (2,100 m) to 13,000 ft (4,000 m). This small perennial is clumpy to mat-forming and spreads from a woody caudex, especially in nooks between rocks. It has stems lined with oval or rounded leaves which spread parallel to the ground or ascend somewhat. At the tips of the thin stems are flowers each with four petals. The petals are magenta to purple, rounded and notched, often in a perfect heart shape, and are one or two centimeters long. The glandular, club-like, ridged fruit is a capsule two to four centimeters long growing on a short stalk.
Clarkia cylindrica is a species of flowering plant in the evening primrose family known by the common name speckled fairyfan, or speckled clarkia.
Camissonia contorta is a species of evening primrose known by the common name plains evening primrose. It is native to western North America from British Columbia to California to Idaho, where it grows in many habitat types. It is an annual herb producing a slender, bending to curling red or green stem which is sometimes hairy. It is up to 30 centimeters long and erect or spreading out. The blue-green leaves are linear to very narrowly oval in shape and up to 3.5 centimeters long. The nodding inflorescence produces one or more small flowers. Each has bright yellow petals up to half a centimeter long, sometimes with small red dots near the bases. The fruit is a capsule about 3 centimeters long containing shiny seeds.
Chylismia heterochroma is a species of evening primrose known by the common name Shockley's evening primrose. It is native to the desert slopes and woodland of eastern California and Nevada. It is a hairy, glandular annual herb growing a spindly stem up to a meter tall. There is a thick basal rosette of leaves which are mostly oval in shape and several centimeters in length, and generally no leaves higher up the stem. The inflorescence produces several small flowers with four oval petals just a few millimeters long and lavender in color with yellow-tinted bases. The fruit is a club-shaped capsule roughly a centimeter long.
Camissonia lacustris is a flowering plant species commonly called grassland suncup. It is an evening primrose endemic to California, where it grows on the grasslands of the Sierra Nevada foothills. It is also known from an area in the Northern Coast Ranges in Lake County.
Camissoniopsis lewisii is a species of evening primrose known by the common name Lewis' evening primrose. It is native to southern California and Baja California, where it grows in coastal habitat and on the grasslands of the inland mountain ranges. as an example occurrence in Baja California, C. lewisii occurs in association with Mimulus aridus and Adiantum jordanii.
Camissoniopsis pallida is a low growing, yellow-flowered annual plant in the evening primrose family, Onagraceae. It is known by the common names pale primrose or pale yellow suncup. It is native to the desert and scrub habitat of the region where Arizona, California, and Nevada meet. It is a roughly hairy annual herb growing in a low patch on the ground, sometimes producing an erect stem from the basal rosette. The herbage is gray-green to reddish green. The leaves are lance-shaped and up to 3 centimeters long. The nodding inflorescence produces flowers with yellow petals 2 to 13 millimeters long, each with small red markings near the bases. The fruit is a straight to tightly coiled capsule.
Tetrapteron palmeri is a species of evening primrose known by the common name Palmer evening primrose. It is native to the western United States from California to Idaho, where it grows in several habitat types, including desert and sagebrush. It is a roughly hairy annual herb growing in a low patch on the ground, generally with no stem. The leaves are widely lance-shaped and up to about 5 centimeters long, with a few small teeth along the edges. The nodding inflorescence produces flowers with yellow petals only 2 or 3 millimeters long each and a noticeable bulbous stigma tip which may be up to a centimeter wide. The fruit is a leathery capsule around half a centimeter long with small wings near the tip.
Taraxia subacaulis is a species of evening primrose known by the common name diffuseflower evening primrose. It is native to the western United States, where it grows in several habitat types, especially in mountainous areas. It is a fleshy perennial herb growing from a taproot and usually lacking a stem. The leaves are lance-shaped to oval and up to 22 centimeters long and are borne on long petioles. The flower has yellow petals, each up to 1.5 centimeters long, and a large, bulbous stigma tip. The fruit is a leathery capsule 1 to 3 centimeters long.
Clarkia arcuata is a species of flowering plant in the evening primrose family known by the common name glandular clarkia. It is endemic to California, where it grows in the chaparral and woodlands of the foothills of the Sierra Nevada and southern Cascade Range. It is an annual herb producing a slender, erect stem often exceeding half a meter in height. The leaves are narrow, usually linear or lance-shaped, and up to 6 centimeters long. The inflorescence bears a few flowers, which dangle when they are buds and grow erect as they open. The sepals stay fused as the petals open and emerge from one side. They are coated in glandular hairs. The petals are up to 3 centimeters long, pink-lavender in color, sometimes with a reddish blotch at the base. They form a bowl-shaped corolla. There are 8 stamens and a protruding, four-chambered ovary. The fruit is an elongated capsule which may reach 3.5 centimeters long.
Clarkia dudleyana is a species of flowering plant in the evening primrose family known by the common name Dudley's clarkia. It is endemic to California, where it can be found in the mountains of the Transverse Ranges and the southern Sierra Nevada foothills. It grows in woodland, forest, and chaparral habitats under 1500 meters in elevation. This annual herb produces an erect stem sometimes exceeding half a meter in height. The leaves are lance-shaped, up to 7 centimeters long, and borne on short petioles. The top of the stem is occupied by the inflorescence, which has opening flowers below closed, hanging buds. As the flower blooms the pink to reddish-purple sepals remain fused, opening along one side only. The petals are up to 3 centimeters long, fan-shaped, pinkish lavender in color and sometimes flecked with red. There are 8 stamens, some of which have large lavender anthers and some that have smaller, paler anthers. The stigma protrudes farther than the stamens.
Clarkia mildrediae is an uncommon species of flowering plant in the evening primrose family known by the common name Mildred's clarkia. It is endemic to California, where it is known from the forests of the southernmost Cascade Range and northern Sierra Nevada. It is an erect annual herb often exceeding half a meter in height. The oval leaves grow up to 6 centimeters long and are borne on petioles of up to 4 centimeters. The inflorescence bears opening flowers and hanging, pointed flower buds. As the bud opens the sepals all separate instead of remaining fused as those of many other Clarkia species do. The triangular to semicircular petals are about 2 centimeters long and lavender to bright reddish-purple, sometimes with dark speckling. There are 8 stamens with anthers all alike, and a protruding stigma.
Clarkia xantiana is a species of flowering plant in the evening primrose family known by the common name gunsight clarkia. It is endemic to California, where it is known from the southern Sierra Nevada and its foothills and the adjacent Transverse Ranges. This is an erect annual herb with linear to lance-shaped leaves each up to 6 centimeters long. The inflorescence produces opening flowers and closed buds. The sepals stay fused as the petals bloom from one side. Each petal is up to 2 centimeters long and generally light to medium purple in color, sometimes with a dark, ringed spot on the petals of the upper whorl. The petal has a narrow claw and a wider blade which has two lobes at the tip with a small tooth between.
Epilobium howellii is an uncommon species of flowering plant in the evening primrose family known by the common names Yuba Pass willowherb and subalpine fireweed. It is endemic to the High Sierra Nevada of California, where it is known from only about 20 occurrences.
Epilobium oregonense is a species of flowering plant in the evening primrose family known by the common name Oregon willowherb. It is native to western North America from British Columbia to Arizona, where it generally grows in moist places in several types of habitat. It is a perennial herb growing spindly erect stems approaching 40 centimeters high or sometimes forming mats spreading via stolons. The small leaves are rounded near the base of the plant and linear in shape farther up the stem. The inflorescence bears flowers with four white to pink petals each a few millimeters long. The fruit is an elongated capsule up to 5 centimeters in length which is borne on a long pedicel which may be longer than the capsule itself.
Oenothera longissima is a species of flowering plant in the evening primrose family known by the common name longstem evening primrose. It is native to the southwestern United States, where it grows in relatively moist areas in scrub and woodland habitat. This is a biennial herb producing a tall, erect stem known to well exceed 2 meters in height. The widely lance-shaped leaves may be 22 centimeters in length and may have slight teeth along the edges. The inflorescence is a spike of showy large flowers. Each has yellow petals which may be more than 6 centimeters in length and fade orange or red with age. The fruit is a lance-shaped capsule up to 5.5 centimeters long.
Oenothera primiveris is a species of flowering plant in the evening primrose family known by the common names yellow desert evening primrose, bottle evening-primrose, and desert evening-primrose.
Oenothera wolfii is a rare species of flowering plant in the evening primrose family known by the common name Wolf's evening primrose. It is native to the coastline of southern Oregon and northern California, where it grows in coastal prairie, dunes, and coastal forest and woodland habitat. As of 1997 it was known from only about 16 occurrences. The biggest threat to the plant is its easy hybridization with its relative and probable descendant, Oenothera glazioviana. As this rare wild plant crosses with the introduced garden escapee, introgression occurs, causing what is known as genetic pollution; fewer pure individuals of O. wolfii will be seen as they are outnumbered by hybrids.
Oenothera harringtonii is a species of flowering plant in the evening primrose family known by the common names Arkansas Valley evening primrose and Colorado Springs evening primrose. It is endemic to the state of Colorado in the United States.
