Plant Story -- Artemisia ludoviciana, silver wormwood, Louisiana sagewort

Pretty, eh?

Artemisia ludoviciana is a common grassland plant, native across the central and western United States, now found in most eastern states as well. It is in the sunflower family, Asteraceae, but it is wind-pollinated and so has tiny gray-green flowers, quite nondescript. It is part of the big group of native western North American plants often called sages because they smell like culinary sage, although they are not related to it (see previous blog post). 

Flowering stalk, Artemisia ludoviciana, silver wormwood

There is no consensus common name for this widespread plant. I found these common names while researching this post: 
white sagebrush (where I saw the name: USDA Plants database), 
Louisiana sagewort (Ackerfield's Flora of Colorado), 
silver wormwood (Flora of North America online) 
white sage (Wildflowers of Larmier County, CO, Illinois wildflowers, Minnesota Wildflowers, Gardenia.net and other sites selling wildflowers), 
silver mugwort (Wells and Groen), 
western mugwort (Mielke) 
prairie sage (Alberta Agriculture and Forestry, Prairie Moon Nursery, My Patriot Supply. Be careful, Artemisia frigida is also called prairie sage)
cudweed sagebrush (Stubbendieck et al.) and
Mexican sagebrush (Dallas County Lepidopterists). (This last, Mexican sagebrush, seems to be an error since a search on Mexican sagebrush brings up several plants but not Artemisia ludoviciana. One variety of Artemisia ludoviciana is Artemisia ludoviciana var. mexicana, so probably the common name intended was Mexican white sagebrush.)

With all that name diversity, any one of us could read about it under a different name and not know it was a familiar plant.  

Artemisia, the genus to which it belongs, includes 200-400 species native all across the world. Several were classical medicinal plants in ancient Greece and Rome. Wormwood, Artemisia absinthium link is the most famous, being a by-word for bitterness ("bitter as wormwood"), a vermifuge, driving out intestinal worms (WORMwood) and a more general medicinal (link, link). Other economically important European Artemisia species were southernwood, Artemisia abronatum (link), tarragon Artemisia dracunculus (link) and mugwort, Artemisia vulgaris (link). In Asia Artemisia species were used medicinally as well. One, Artemisia annua, called sweet wormwood or sweet annie in English (link), is the source of the active ingredient in the most effective anti-malarial drug in use today, an application which gave Youyou Tu the 2015 Nobel Prize for medicine (link).  


Artemisia ludoviciana was collected for science for the first time by the Lewis and Clark Expedition (as wormwood). Consequently, its species epithet, ludoviciana, "of Louisiana," commemorates that it was found in the area bought in the Louisiana Purchase. 

Louisiana sagewort, silver wormwood, Artemisia ludoviciana

In North America, especially the West, there are at least 50 native Artemisia species. They're common but not very distinctive, so few people know them well. Common names, often refer them to their European relatives, calling them wormwoods and mugworts, or indicate the smell, calling them sages, sagebrushes, and sageworts (wort is an old word meaning plant). Artemisia ludoviciana is not alone in having several quite different common names. Not surprisingly, diverse common names for a large group of similar American plants creates confusion. 

For Artemisia ludoviciana the common name that is a particular problem is white sage. Salvia apiana of California is also called white sage. California's white sage,  related to culinary sage, was sacred to several tribes in California. It is highly regarded for making smudge incense (link, link). However, it grows wild only in California (see map). People who gather white sage anywhere else in the United States are gathering something else, most likely Artemisia ludoviciana. Artemisia ludoviciana makes a decent sagy incense that was used by Native Americans throughout its range, but it is biologically and chemically quite different from Salvia apiana.

What should we call it? I've always said Louisiana sagewort. That's ok, but its based on smelling like sage (Salvia) and it is not a Salvia. Silver wormwood or silver mugwort seem somewhat better since they refer it to its (European) relatives. My personal preference is silver wormwood. I have grown wormwood (A. absinthium) and like it. If you didn't know the wormwood plant, the name might put you off. Calling it silver wormwood matches the Flora of North America, though, so it puts me in good company.

Healthy young shoots of silver wormwood

I hope have now called it something you recognize, since it probably grows near you if you are the continental United States.  In mid-continent it is easily recognized as pretty much the only plant that is clonal, gray and smells like sage. But in the Great Basin, there are other Artemisia species that fit that description.

Sulfur flower, penstemons and lots of silver wormwood, only
slightly silvery in the photo but a big mass behind the bright flowers.
If you walked through it the smell of sage would be obvious.

Native American uses for silver wormwood were very very numerous. They fill four columns in Moerman's big book, Native American Ethnobotany, and four pages (180 entries) in the online version. The uses include as treatment for a sore throat, colds and diarrhea, as poultices and rinses for skin problems, for ceremonial cleansing--a very important role--, as incense, to make mats and rugs, and in various charms. Recent research found the leaves to indeed be antimicrobial and antioxidant.

Range managers don't have much nice to say about silver wormwood because domestic animals rarely eat it.  Most native animals don't like it much either, although that varies somewhat across its range and between species.  (A USDA page on silver wormwood (link) says it is the chief food of sage grouse, but no other source reports that. Where sage grouse web pages mention an actual sagebrush species, it is big sagebrush Artemisia ttridentata, fringed sagewort A. frigida or  black sagebrush A. nova (link, link), which suggests A. ludoviciana is not a preferred species.)

Its success repelling bigger animals isn't the case for insects. It is a host plant for both the American lady butterfly (Vanessa virginiensis, photos) and the painted lady butterfly (Vanessa cardui, photos). "Host plant" means the butterfly lays her eggs on the plant and the caterpillars eat it until they grow big enough to pupate and become adult butterflies. The sagy smell will attract the butterflies and the sharp chemicals that create the smell are no problem.

Silver wormwood also has a specialist grasshopper. Most North American grasshoppers are generalists, eating quite a variety of plants. The cudweed grasshopper Hypochlora alba (photos) prefers silver wormwood often eating only silver wormwood. Not only do cudweed grasshoppers thrive on silver wormwood, their color matches the plant. The vast majority of grasshoppers are brown, yellow or green (link). Cudweed grasshoppers are the distinctive color of silver wormwood, providing very effective camouflage (link).

People have for years substituted it for culinary sage in their cooking. The two plants are not the same: you might want to compare the taste, since people vary in their liking for silver wormwood. I don't actually recommend using silver wormwood as a spice because its toxicity hasn't been much studied and most of the Native American uses were external. However, traditional spices are eaten in tiny amounts and would probably not be good for you in larger quantities, likewise spice-quantity amounts of silver wormwood don't appear to have poisoned anyone. (Caveat: it is a wind-pollinated relative of ragweed, people allergic to ragweed be very careful of it. Culinary sage is not a rageweed relative.)

silver wormwood expanding

I personally like silver wormwood's sagy smell and silver color.  It is a drought-tolerant native wildflower, even though the flowers are inconspicuous. I planted it in the little patch of native grassland I created in my back yard. That experience has tempered my liking for it, because it very quickly spread all across that area and then sent shoots out into the surrounding lawns and flowerbeds. I can easily weed it out of places I don't want it, but I have to be vigilant. I still like the smell and the silver color is lovely among the greener grasses. I'm watching for butterfly caterpillars and silver-green grasshoppers.

Comments and corrections welcome.

References
Ackerfield, J. 2015. Flora of Colorado. Botanical Research Institute of Texas Press, Fort Worth, Texas.
Alberta Agriculture and Forestry. Alberta range plants and their classification. link
Cudweed grashopper, Hypochlora alba (Dodge) U. Wyoming Entomology link
Dallas County Lepidopterists Society. List of host plants for butterflies link
Flora of North America online link
Hilty, J. 2017. White sage, Artemisia ludoviciana gnaphaloides Illinois Wildflowers website link
Lopez-Lutz, D., D.S. Alviano, C. S. Alviano and P. P. Kolodziejczyk. 2008. Screening of chemical composition, antimicrobial and antioxidant activities of Artemisia essential oils. Phytochemistry 69(8): 1732-1738.
Mielke, J. 1993.Native plants for southwestern landscapes. University of Texas Press, Austin Texas.
Minnesota Environment and Natural History Resources Trust Fund. Minnesota Wildflowers link 
Moerman, D. "Artemisia ludoviciana" Native American ethnobotany online link
My Patriot Supply link
U.S.D.A. Plants link
Stubbendieck, J., S. L. Hatch and K. J. Hirsch. 1986. North American range plants. University of Nebraska Press, Lincoln, Nebraska.
USDA NCRS Data Center. White sage, Artemisia ludoviciana  link
Wells, D. and J. Groen. 2006. Plants of the Sonoran Desert and their many uses. Wells/Groen Publishing Company, Apache Junction Arizona.  (They call it silver mugwort, then confuse Artemisia ludoviciana with A. vulgaris.)

Kathy Keeler, A Wandering Botanist

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