Silver King Artemisia

What’s blooming in the area: Tea and miniature roses in town, white sweet clover, purple asters; dead leaves on catalpa and some cottonwoods, others still yellow.
What’s blooming in my garden: California poppy, Mexican hat, chrysanthemum, chocolate flower near house; peach, rose of Sharon, Siberian pea and caryopteris dropping leaves; cold killed leaves on apricot, black locust, weigela, cutleaf coneflower, Maximilian sunflowers; leaves beginning to yellow on Apache plume, flax, sea lavender, some iris; leaves turning red on pink evening primrose.
Bedding plants: Snapdragon, sweet alyssum.
Inside: Aptenia, zonal geranium
Animal sightings: Rabbit reconnoitering last Sunday.
Weather: Temperature fell to mid-20's on Thursday and low 30's Friday and Saturday. Last rain, 10/14/2008; 10:15 hours of daylight today.
Weekly update: It’s not that I didn’t know. Milaeger was quite open when it said Silver King artemisia "will spread very quickly." A few years later they modified that to "rampant grower."
But sometimes that’s what you want - dense foliage that will quickly and cheaply fill an area where other plants won’t grow. I don’t remember now where I put the disc-flowered composite in Oakland County in 1986, but I do know it didn’t do particularly well. Michigan may be the only state in the country where Artemisia ludoviciana is considered a threatened species.
But that was there.
I didn’t deliberately bring the grey-leaved perennial to New Mexico. A piece of rhizomatous root stuck in a pot with something else in 1991, and emerged the next summer in my holding bed. I moved the survivor to the northwest side of the house in 1997 where it formed a colony the next summer. Not only did it begin to spread, but it hitchhiked again when I move a white yarrow, The Pearl, from there to the northwest side of the garage in April of 1998.
Now both beds would be overrun if I let them. It turns out, Silver King is a common name for the albula strain of the mexicana subspecies that’s native to the arid southwest from Colorado-Utah-Nevada south into México. Here it stays in range of the hoses and prefers the shelter of buildings, and so doesn’t follow the water into more exposed, sunnier areas.
The ancestral mexicana grows in the central highlands of México above 5,500' where it has been used medicinally by both the Aztec and the Spanish. In the Chiricahua mountains of southeastern Arizona, it prefers the canyons and limestone soils. George Osterhout found a variant, silvicola, with larger heads in Colorado that stayed along the northern streams, much like my cultivated variety.
So far I’ve let the mexicana albula grow at the outer edges of the beds, hoping the height, usually 18" to 24" by August, would shelter the more desirable plants during the summer heat and winds. The roots are fairly shallow, so they don’t compete directly with the nearby deeper rooted perennials. While the rhizomes haven’t gotten too dense, the multiple shoots with their flower bearing branches will crowd out the phlox and coneflowers. I have to spend at least one day a year, and sometimes more, keeping it to the periphery.
Sometimes I wonder why I’m so generous, but I know the reason’s aesthetic. Silver King has insignificant flowers that recently have been turning to seeds, but the herbaceous foliage is a good contrast with the blue flowers by the house and the phlox and lilies by the Navajo white garage where it grows out to the equally gray winterfat. More than Vita Sackville-West have enjoyed a garden limited to shades of white.
Invasiveness is in the eye of the overrun. In most parts of the country, proscribed plants are introduced aliens like kudzu or Siberian elms that do better than expected and escape into the wild. My most aggressive plants are natives to the region that don’t grow in this particularly hostile area, but are well adapted to flourish once those barriers are accidentally removed.
Notes: Bennett, Peter S., E. Roy Johnson and Michael R. Kunzmann. An Annotated List of Vascular Plants of the Chiricahua Mountains, 1996, available on-line.Heinrich, Michael. "Ethnobotany, Phytochemistry, and Biological/Pharmacological Activities of
Artemisia ludoviciana ssp. mexicana (Estafiate)" in Colin W. Wright, Artemisia, 2002.Milaeger Gardens, The Perennial Wishbook catalogs, 1987, 1993.Osterhout, George E. Included in John Merle Coulter and Aven Nelson. New Manual of Botany of the Central Rocky Mountains (Vascular Plants), 1909.
Photograph: Silver King artemisia, 19 September 2008.