See yellow Oenotheras.

Semi-desert, foothills. Openings, sand. Spring.
Canyons of the Ancients National Monument, April 22, 2016.

This often low-to-the-ground annual or winter annual is fairly common, sometimes very common, and its very large white flowers quickly catch attention. The first flower of the season is usually, as shown here, erect, but as the plant grows (sometimes to 10 inches tall), flower stems will often bend outward and then upward.

Basal leaves range from entire to deeply dissected (pinnatifid) and stem leaves are often progressively smaller and also deeply dissected. The plant is often so small that the stem leaves are difficult to see, but a close look with a hand lens or with a macro camera reveals the stem leaves. These stem leaves are important to look for because the presence of stem leaves immediately tells you that you are not looking at the very common Oenothera caespitosa which has no stem, no stem leaves; it is acaulescent. See below.

Frederick Pursh named this plant in his 1814 Flora Americana from a specimen collected by John Bradbury in the upper Louisiana Territory.  "Albicaulis" is Latin for "white-stemmed". 

More Oenothera photographs.

Semi-desert, foothills, montane. Disturbed areas, openings, sand. Spring, summer.
McElmo Canyon, Canyons of the Ancients National Monument, April 27, 2005 and
Near Shiprock, South of the Hog Back, New Mexico, April 24, 2007.

This is a very common, wide ranging, Evening Primrose with a number of common varieties.  It has very large white flowers, spreads by underground roots, and is often abundant in large colonies on steep dry slopes and sandy soils.  The entire plant is quite low to the ground, and the flower, disproportionately large for the size of the rest of the plant, often touches the ground.  Leaf length and depth of serrations and teeth varies.  Flowers often open in the evening and wither to pink with the sun and heat of the next afternoon.

"Caespitosa", "growing in tufts", refers to the dense tufts of basal leaves and stems.

More Oenothera photographs.

Thomas Nuttall collected this plant along the banks of the Missouri in South Dakota in 1811 and named it in 1813. However, Meriwether Lewis collected this species July 17, 1806 in Montana, near the Falls of the Missouri. Click to read why Lewis' collection is not considered the type.

Semi-desert, foothills. Openings, sand, rocks. Spring.
Hidden Valley Trail, Moab, Utah, April 13, 2015 and near Corona/Bow Tie Trail, Utah, May 27, 2016.

This lovely Evening Primrose is found almost exclusively on the Colorado Plateau. At first glance it might be taken for Oenothera albicaulis, but another look reveals that the leaves are distinctly different and that O. caespitosa subspecies navajoensis buds tend to be more erect than those reclining buds of O. albicaulis. An even more detailed examination will show that although the flower petals are just about the same size (O. caespitosa ssp. navajoensis are 2.8-3.2 mm and those of O. albicaulis are 2-3.5 mm), the floral tube of ssp. navajoensis is usually twice the length of the tube of O. albicaulis. The sepals are about the same length. An even more detailed examination will show that navajoensis is perennial, albicaulis is annual and even deeper exams will show that the seed capsules of navajoensis are swollen and quite bumpy whereas those of albicaulis are narrow and relatively smooth.

This subspecies differs from other subspecies of O. caespitosa in several characteristics of its seed capsule, in the length of its floral tube, in the hairiness of its leaves (notice the light glow of white hairs along the leaf edges and the surface),

and in its tendency to be solitary rather than colonial.

"Caespitosa", "growing in tufts", refers to the dense tufts of basal leaves and stems.

This subspecies was first collected along the Paria River in Kane County, Utah, in 1965 by Arthur Cronquist and it was named and described by Wagner, Stockhouse, and Klein in 1985.

Foothills, montane. Woodlands, openings. Spring, summer.
Near Yellowjacket Canyon, June 6, 2004 and July 23, 2016.

The very finely cut leaves, large white flowers, and spreading clusters of this slender Oenothera distinguish it.  Oenothera coronopifolia often grows in colonies of many plants; areas of the foothills would have this as a common plant if it were not for cows, alfalfa fields, and lawn mowers.

The etymology of the specific epithet "coronopifolia" is debatable but ultimately the meaning is the same: "deeply divided leaves". The Latin "coron" means "crown" and the epithet would then refer to the resemblance of the deeply cut leaves to the deep indentations along the top rim of a crown. The Greek meaning of "coron" is "raven" and the epithet would then refer to the resemblance of the deeply cut leaves to the deep indentations of a Raven's foot. The epithet also refers to the resemblance of this Oenothera's leaves to those of the Mustard genus, Coronopus. 

The plant was first collected by Edwin James in 1820 near the forks of the Platte River and was described by Torrey and Gray in their 1840 Flora of North America.

More Oenothera photographs.

Semi-desert, foothills. Shrublands, openings. Spring, summer.
Butler Wash, Utah, April 7, 2005.

Oenothera pallida is highly variable in its growth characteristics: it can be an annual or, more commonly, a perennial; its height is from eight to twenty-four inches; stems are red and fleshy but often are woody and flaky in older plants; stems commonly lean and arch; leaves are narrow but can be entire, toothed, or deeply cut; plants can be glabrous (smooth without hairs) or hairy.  Plants often spread from roots and can be so abundant that an area is dotted with red stems in early spring and then with numerous, glorious white flowers.  Petals have noticeable yellow/green patches at their base. 

John Lindley named this species from a specimen collected by David Douglas (of Douglas Fir fame) in the early 1800s in the "north-west of North America".  (Douglas' words as quoted in Intermountain Flora.)  "Pallida" is Latin for "pale". 

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Oenothera albicaulis

Range map for Oenothera caespitosa ssp. marginata

Range map for Oenothera caespitosa ssp. navajoensis

Range map for Oenothera coronopifolia

Range map for Oenothera pallida