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    Linnaeus named this genus in 1753 using a name given several thousand years ago by Theophrastus to another genus in this family. The meaning of "Oenothera" is not agreed on; Greek gives us both "oenos" for "wine" and "thera" which is variously translated as "to seek", "to imbibe", "to catch", "to hunt". "Thera" could indicate that the plant (really just the root) was used to flavor wine, or the root was used to absorb wine and was then fed to animals to calm them, or the juice of the root was put in wine to seduce, or the root in wine just plain made people happy.  

    See yellow Oenotheras.

Oenothera albicaulis
Oenothera albicaulis (White-stemmed Evening Primrose)
Onagraceae (Evening Primrose Family)

Semi-desert, foothills. Openings, sand. Spring.
South of the Hog Back, New Mexico, April 24, 2007.

This low-to-the-ground annual or winter annual is fairly common and its very large white flowers quickly catch attention.  Basal leaves range from entire to deeply dissected (pinnatifid) and stem leaves are often progressively smaller and also deeply dissected.

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. 

Oenothera caespitosa subspecies navajoensis
Oenothera caespitosa subspecies navajoensis (Navajo Evening Primrose)
Onagraceae (Evening Primrose Family)

Semi-desert, foothills. Openings, sand, rocks. Spring.
Hidden Valley Trail, Moab, Utah, April 13, 2015.

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 navajoensis buds tend to be more erect than those reclining buds of 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 the length of its floral tube, the hairiness of its leaves (notice the light glow of white hairs along the leaf edges and the surface),

                                                       Oenothera caespitosa subspecies navajoensis

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.

Oenothera caespitosa
Oenothera caespitosasubspecies marginata (Matted Evening Primrose)
Onagraceae (Evening Primrose Family)

Semi-desert, foothills, montane. Disturbed areas, openings, sand. Spring, summer.
McElmo Canyon, Canyons of the Ancients National Monument, April 27, 2005.

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.

Oenothera coronopifolia (Cut-leaf Evening Primrose)
Onagraceae (Evening Primrose Family)

Foothills, montane. Woodlands, openings. Spring, summer.
Near Yellowjacket Canyon, June 6, 2004.

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.

"Coronopifolia" means "having leaves like the Mustard, 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.

Oenothera pallida
Oenothera pallida (Pale Evening Primrose)
Onagraceae (Evening Primrose Family)

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". 

More Oenothera pallida photographs.

 

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

Oenothera caespitosa ssp. navajoensis

Range map for Oenothera caespitosa ssp. navajoensis

Range map for Oenothera coronopifolia

Range map for Oenothera pallida