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A Biennial Dicot, Oenothera Pallida is a member of the evening-primrose family (family Onagraceae) which consists mainly of herbs (rarely shrubs or trees); often with showy flowers borne individually in racemes or branched clusters or in spikes. The genus Oenothera has about 125 species of biennial, perennial and annual herbaceous flowering plants native to North and South America. Common names include evening primrose, suncups, and sundrops.
This plant reaches 8 to 20 in. tall and spreads 8 to 12 in. wide. The 1 to 2 inch green leaves are lance-shaped, entire, and glabrous on both sides. The common name "evening primrose" is perceptibly drawn from the fact that the flowers open only in the evening. These four-petal flowers are fragrant and white, but yellow, purple, pink or red in other species. One of the most distinctive features is an X shape that is formed by the stigma with four branches. Moths and bees provide pollination, but not any bee; like many members of the Onagraceae, a morphologically specialized bee is required to gather the pollen grains which are loosely held together by viscin threads. In addition, the flowers are open in a season (April and May for species Pallida) when most bee species are inactive, so the bees which visit Oenothera are also compelled to be vespertine temporal specialists. Pale Evening Primrose seeds ripen from late summer to fall. Many larvae species feed on this plant, mostly from the Lepidoptera larvae species. Some larvae in that species actually feed exclusively on this plant genus.
Interestingly, it is theorized that the genus Oenothera may have originated in Mexico and Central America. The theory identifies that a succession of ice ages swept down across North America during the Pleistocene era, with intervening warm periods. This was repeated for four ice ages, resulting in four separate impacts of colonization, each hybridizing with the remnants of the previous impact. The current rich genetic diversity in this genus along with genetic studies supports this theory.
It has been well considered before colonization of the Americas that most species of Oenothera provide effective healing for asthmatic coughs, gastro-intestinal disorders and as a sedative pain-killer. Surprisingly, this has gone without present-day clinical trial investigations. The complete plant is edible; the roots eaten like a vegetable and the shoots in salad.
Region and Habitat
A native plant of the United States, Pale Evening Primrose is found in Forb/Herb habitats in the following states: AZ, CO, ID, MT, NV, NM, OR, TX, UT, WA, and WY. In Utah, as shown in the map in the left margin, it is found across the state from elevations of 910 to 2,580 meters. The southeast county of San Juan contains a subspecies known to 7 other states as Oenothera Pallida Lindl. ssp. pallida. This subspecies is shown in the plant genealogy chart below and pictured in the last photo.
Evening primroses act as primary colonizers, springing up where patches of bare, undisturbed ground may be found. This would include poorer environments such as roadsides, dunes, railway embankments and wasteland. Oenothera Pallida is found in areas of high sun and has a low water requirement with a high CaCO3 tolerance.
Genealogy
| Kingdom | Plantae – Plants |
| Subkingdom | Tracheobionta – Vascular plants |
| Superdivision | Spermatophyta – Seed plants |
| Division | Magnoliophyta – Flowering plants |
| Class | Magnoliopsida – Dicotyledons |
| Subclass | Rosidae – |
| Order | Myrtales – |
| Family | Onagraceae – Evening Primrose family |
| Genus | Oenothera L. – evening-primrose |
| Species (all over Utah) | Oenothera Pallida Lindl. – pale evening-primrose |
| Subspecies (San Juan County) | Oenothera Pallida Lindl. ssp. pallida – pale evening-primrose |