Mexican Evening Primrose.
Oenothera caespitosa, Evening Primrose Family ( Onagraceae ), Mexican Evening Primrose. Also called: Oenothera berlandieri, Pink Ladies, Pinkladies, White Evening Primrose, Showy Evening Primrose.

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This Primrose usually blooms in March to April in Arizona. If given water, it can become invasive. All parts are poisonous. About a third of the people who plant it, later on, want to remove it.

It's alternate leaves are up to 2-3" long and �" across. They are lanceolate, elliptic, or oblanceolate in shape, while their margins are smooth (entire), dentate, or shallowly pinnatifid. A few leaves may have paired basal lobes. The leaves will either be sessile against their stems or they have petioles up to about 1 inch in length. Both the upper and lower leaf surfaces will be light to medium green, and be either glabrous or sparsely appressed-pubescent.

About 1 - 3 flowers develop from the axils of the upper leaves. These appressed-pubescent flower buds are long and spindle-shaped. The flowers open during the daytime, and they will be about 2 - 3�" across. The flower has 4 broad petals, & 8 stamens with either white or yellow anthers. They will have a long white stigma that is 4 - clefted at the tip. These flowers are usually pinkish white; & they have fine pink lines that radiate outward from their throats across the wrinkled petals. The throats of these flowers are usually yellow.

The flowers attract bees, moths, and hummingbirds.

Quick Notes:

Height: Up To 10 inches tall, and up to about 2 - 3 feet in diameter.

Flowers: Flowers Pinkish. about 2 - 3�" across. 4 broad petals, 8 stamens with white or yellow anthers.

Flowers: Up to about 8 inch stems.

Flowering Time: April - September.

Leaves: Leaves are in a basal rosette. Green, fuzzy leaves. alternate leaves are up to 2-3" long and �" across. They are lanceolate, elliptic, or oblanceolate in shape, while their margins are smooth (entire), dentate, or shallowly pinnatifid.

Found: Native to the rocky prairies and savannas of the lower Midwestern USA. The USDA claims it is native of the USA (AL, AR, AZ, CA, CT, FL, GA, IA, IL, IN, KS, KY, LA, MO, MS, NC, NE, NM, OH, OK, PA, SC, TN, TX, UT, VA, WV).

Hardiness:
USDA Zone 5a: to -28.8 �C (-20 �F)
USDA Zone 5b: to -26.1 �C (-15 �F)
USDA Zone 6a: to -23.3 �C (-10 �F)
USDA Zone 6b: to -20.5 �C (-5 �F)
USDA Zone 7a: to -17.7 �C (0 �F)
USDA Zone 7b: to -14.9 �C (5 �F)
USDA Zone 8a: to -12.2 �C (10 �F)
USDA Zone 8b: to -9.4 �C (15 �F)
USDA Zone 9a: to -6.6 �C (20 �F)
USDA Zone 9b: to -3.8 �C (25 �F)

Soil pH requirements:
6.1 to 6.5 (mildly acidic)
6.6 to 7.5 (neutral)
7.6 to 7.8 (mildly alkaline)
7.9 to 8.5 (alkaline)

Sun Exposure:
Full Sun.

Elevation: 1,200 to 7,500 feet In Arizona.

Habitat: Arizona roadsides, ponderosa forest clearings, dry, rocky slopes; disturbed ground.

Miscellaneous: Photos Taken; March 19, 2008. Glendale, Arizona. An ideal xeriscape landscape plant at low elevations in Arizona.