Yellow Evening Primrose

What’s still green: Arborvitae, juniper and other evergreens, some rose stems, cholla, prickly pear, yuccas, Japanese honeysuckle faded, sweet peas, coral bells, sea pink, snapdragons, purple aster; snow covers grape hyacinth, vinca, beardtongues, pink and yellow evening primroses, chrysanthemums, cheat grass.

What’s grey, blue-grey or grey-green: Piñon, pinks, snow-in-summer, yellow alyssum, saltbush, winterfat.

What’s red: Saint John’s wort.

What’s yellow: Weeping willow branches.

What’s blooming inside: Christmas cactus and aptenia; rochea and Christmas cactus leaves tinged with red.

Animal sightings: Rabbit tracks.

Weather: 3" of snow Wednesday; warm temperatures since, but snow remains in the northern and western beds; 10:34 hours of daylight today.

Weekly update: It’s hard to remember I once wanted to grow yellow evening primroses. I actually bought seeds, lots of them. But none germinated. Then, in 2000, one took root and by 2002 I was removing basal rosettes from any place near a hose. The next year Japanese beetles ate every member of the Onagrace family before threatening the roses. I’ve been yanking them ever since.

I’m not sure what ended up growing, but suspect it’s the local weed that can get to be six feet tall, with branches reaching out several feet. Large, four-petaled flowers, that resemble footed chalices, appear near tips of those branches late in the day beginning the end of June and peaking in late summer. They’re effective in abandoned fields, but in my garden, they’re simply too big. The biennials refuse to stay with the sunflowers on the dry periphery where I let tall plants roam.

Some of those seeds I bought were called Oenothera lamarckiana; others were listed as biennis or hookeri. They all looked alike. Indeed the same picture was used by three different seed companies for two species.

They all claimed it preferred "well-drained dry soil. The closest anyone came to warning the wildflower could become a pest was the one that said it "naturalizes in meadows and roadsides." No one admitted it was a wetland plant that was going to invade the choicest irrigated locations.

Seedsmen can be forgiven the problems in nomenclature. Botanists have been arguing ever since Hugo DeVries discovered evening primroses violated the most fundamental rule of Mendelian inheritance, that the children of a mixed marriage (the F1 generation) are all alike, and the grandchildren (the F2 generation) revert to the 1:2:1 variation pattern. The lamarkiana he found in a potato field near Hilversum, Holland, had unpredictable children and reliable grandchildren. They lead him to propose the existence of mutations.

Later biologists have kept the idea of mutants, but determined his plants were something else. Two of them, biennis and hookeri, are closely related, distinguished by the arrangement of their chromosomes. Ronald McGregor says biennis petals on the great plains are 1 to 2.5 centimeters long, while those of the other are 2 to 4 centimeters.

It’s easier to remember the first grows everywhere, but is native to the eastern part of the continent where it’s been mentioned by the Cherokee, Iroquois, Ojibwa, and Potawatomi. The other, now called Oenothera elata, grows in the west where it’s been used by the Jemez, Zuñi, Navajo, and Paiute. The smaller petals may have been an adaption as the genus spread north from central America following the retreat of the glaciers.

All anyone knows for sure about lamarkiana is that it was collected around 1796 by André Michaux somewhere on his trip from South Carolina to the Mississippi, but it’s not been found in the wild since. His notes were lost on his voyage home. Joseph Cunningham says DeVries’ specimens were introduced in commerce in 1860 from plants that had been growing in Lancashire since 1805. Taxonomists agree lamarkiana probably was some kind of hybrid, but can’t agree on the parents.

The violation of rules, of course, is what makes the yellow primroses such a nuisance. The fleshy taproots are easy enough to remove in the spring when the soil is wet. But, after the heat of summer arrives and I’ve retreated to the house, next year’s crop germinates. The reddish-brown seeds respond to long days and warm temperatures.

When the leaves first come up they look like seedlings of coreopsis and coral beardtongues. At best, I can distinguish them then by feel: they’re rougher than their neighbors. By the time the characteristic grey-green color arrives with the white veins, the roots are so long they can only be removed the next time the ground is wet. I’m reduced to chopping down stalks in the morning before the seed pods form.

Since the cold temperatures and snows of November, last summer’s seedlings have stayed green. Last week’s rain fell on saturated ground. The terraced beds, with their brick walls that prevent water erosion, turned into frozen ponds. Last Saturday the primrose plants lay under ice. This week they were buried by snow. These survivors of the ice age will still be here to bolt this summer when my favorite plants, some with warnings they don’t like cold or wet feet in winter, will have died.

I don’t care if they’re mutants or identical siblings or rugged individualists. I want them gone. Even Adolph Hecht, a man who spent thirty years studying them, admits "its principal fault in gardens, including mine, is that it often grows and reproduces only too efficiently."

Notes: Lamarkiana from Fredonia, Lake Valley (1988), Orol Ledden, and Wildseed; biennis from Seeds of Change and Territorial; hookeri from Lake Valley (1998).

Ensminger, Peter A. and Hiroshi Ikuma. "Photoinduced Seed Germination of Oenothera biennis L III. Analysis of the Postinduction Period by Means of Temperature," Plant Physiology 86:475-481:1988.

Cunningham, Joseph Thomas. Hormones and Heredity, 1921, on DeVries’ plants.

Hecht, Adolph. "The Evening Primrose Path," Plant Science Bulletin 14:1-3:1968, on DeVries’ work.

McGregor, Ronald L. "Onagraceae Juss., the Evening Primrose Family," in Great Plains Flora Association, Flora of the Great Plains, 1986.

Moerman, Dan. Native American Ethnobotany, 1998; biennis was also reported in studies of the Gosiute of Utah and the Lakota of South Dakota; elata was also identified by the Pomo of California.

Gates, R. Ruggles. "Some Phylogenetic Considerations on the Genus Oenothera, with Descriptions of Two New Species," Journal of the Linnean Society of London, Botany 49:173-198:1933.

Photograph: Yellow evening primrose under a layer of ice, 31 January 2010; a coral beardtongue, reddened by the cold, is at the bottom right; remnants of purple asters flowers landed on top.