Nomenclature Summary

Artemisia tridentata Nutt., Trans. Amer. Philos. Soc., ser. II, 7: 398. 1841. (Asteraceae) - big sagebrush. Synonymy: Seriphidium tridentatum (Nutt.) W. A. Weber

Artemisia arbuscula Nutt., Trans. Amer. Philos. Soc., ser. II, 7: 398. 1841. (Asteraceae) - little sagebrush. Synonymy: Seriphidium arbusculum (Nutt.) W. A. Weber

Artemisia nova A. Nelson, Bull. Torrey Bot. Club 27: 274. 1900. (Asteraceae) - black sagebrush. Synonymy: Seriphidium novum (A. Nelson) W. A. Weber

Artemisia tripartita Rydb., Mem. New York Bot. Gard. 1: 432. 1900, based on Artemisia trifida Nutt., Trans. Amer. Philos. Soc., ser. II, 7: 398. 1841, nom. illeg. non Turcz., 1832. (Asteraceae) - three-tip sagebrush. Synonymy: Seriphidium tripartitum (Rydb.) W. A. Weber

      Lewis and Clark buried two caches of plant specimens in 1805 with the intention of retrieving them in 1806. The spring runoff in 1806 flooded both caches (one on White Bear Island near Great Falls, the other at Camp Disappointment now under Clark Reservoir south of Dillon, Montana). It is likely that both caches contained specimens of the western sagebrushes.

Artemisia tridentata Nutt. var. tridentata

      Big sagebrush (Artemisia tridentata) is composed of four or perhaps five varieties. Three are widespread in the drier parts of the American West and characterize the plant communities where they occur and it is likely Lewis and Clark encountered all three. Big sagebrush (or Great Basin sagebrush), the var. tridentata, is normally a large, robust plant typically of an irregular shape. The typically sprawling inflorescences are usually large, broad and are found arising from various levels on the shrub and thus of various heights on the plant. The crushed leaves have a spicy odor. The plant is widespread in the West, extending from British Columbia and Alberta in Canada to Baja California, Mexico. To the east it extends as far south as northern Arizona and New Mexico. This is mainly a low elevation plant (typically below 8000 feet), and agricultural lands now occupy much of its native range.

Artemisia tridentata Nutt. var. vaseyana (Rydb.) B. Boivin

      Vasey's sagebrush (Artemisia tridentata var. vaseyana) is a shorter plant that is more or less flat-topped with its narrow, upright inflorescences all arising to approximately the same height from approximately the same level on the shrub. The crushed leaves of this variety have a sweet, camphor-like odor. This plant shares much of the same northern range as var. tridentata. It is found from southern Canada to California, Nevada, Utah and Colorado but at a much higher elevation (up to 10,000). However, in the arid foothills of the Intermountain West the two varieties have overlapping ranges; this is less commonly so along the Lewis and Clark Trail to the north.

Artemisia tridentata Nutt. var. wyomingensis (Beetle & A. Young) S. L. Welsh

      Wyoming sagebrush (Artemisia tridentata var. wyomingensis) also is a shorter plant like Vasey's sagebrush but has the irregular shape of big sagebrush. This is a plant of the plains and foothills (although in the Intermountain West it can be found at elevations as high as 8500 feet) from the western edge of the Great Plains from western North Dakota to Colorado, westward to Idaho, southeastern Oregon, eastern California and northern Arizona. Like var. tridentata crushed leaves have a spicy odor.

      Of the three varieties of big sagebrush that Lewis and Clark would have encountered, Wyoming sagebrush would have been the most common. Both var. tridentata and var. vaseyana were certainly seen in portions of western Montana and Idaho, and the latter especially so in the higher mountains. The majority of leaves of big sagebrush are apically 3-toothed and therefore differ from silver sagebrush (Artemisia cana) that Lewis gathered in 1804. Both explorers mention sagebrush in their journals but no differentiation of the varieties is noted. In the field, the differences can be striking but to the casual observer these differences can go unnoticed unless in mixed populations. Such populations do occur today along the route taken by Lewis and Clark.

      The failure of Lewis and Clark to return to Philadelphia with specimens of big sagebrush meant one of the American West's most distinctive shrubs would go unnamed for another three decades. In 1834, Thomas Nuttall carefully gathered the various kinds of sagebrush he found along what was destined to be the Oregon Trail. In 1841 he described several of the species. Among these was little sagebrush, Artemisia arbuscula.

Artemisia arbuscula Nutt.

      Little (or dwarf) sagebrush is similar to big sagebrush and the crushed leaves have the same spicy odor. As implied by its common name, Artemisia arbuscula is a much smaller shrub (the body of the shrub is rarely over a foot high compared to big sagebrush which can be ten feet tall or even more in exceptional situations). The inflorescences of little sagebrush are decidedly narrower and distinctly spike-like compared to the broader, almost bushy inflorescences of big sagebrush.

      There are four poorly defined varieties within little sagebrush, and Lewis and Clark could have encountered two of them. The var. arbuscula is a plant of dry hillsides and plains where the soil is shallow and often rocky and thus less favorable a site than typically occupied by big sagebrush. The variety is widespread being found from Washington to California and eastward to western Montana, Wyoming and northern Colorado. The explorers would have encountered this variety in western Montana.

      On the alkaline clay flats of western Montana, Lewis and Clark might have seen the lobed litte sagebrush, Artemisia arbuscula var. longiloba. This is not common because of its restricted habitat, but it is found from southeastern Oregon, southern Idaho and western Montana south northern Nevada, Utah and northwestern Colorado. The var. longiloba has more deeply lobed leaves compared to var. arbuscula, but the feature is not consistent and the taxonomic distinctiveness of the variety is questionable.

      Artemisia arbuscula was found by Nuttall on the Snake River plains of southern Idaho in the summer of 1834; it was named in 1841.

Artemisia nova Nutt.

      Closely allied to little sagebrush is black sagebrush (Artemisia nova). This is by far one of the most distinctive expressions of the Artemisia tridentata complex and yet one of the last to be named. It was found by Thomas Nuttall in 1834 and even given a name, but only on his plant label. The species was finally given a name by the Wyoming botanist Aven Nelson in 1900. Destined to eventually be the president of the University of Wyoming, Nelson was a keen observer of Rocky Mountain plants, and black sage (as it is frequently termed by ranchers) was certainly a differ kind of plant to the sheep and cattle ranchers of Wyoming as it was particularly favored by sheep.

      Black sagebrush is a low shrub and is a dark, almost blackish gray in color. The leaves are three-toothed as in the other species mentioned here, but unlike those, these have small, green, gland-like swellings that show through the dense hairs but only when examined with a hand lens. More easy to observed is the essentially glabrous, shiny, yellow-green bracts that surround the tiny flowers. In the other species these bracts are typically densely hairy (tomentose) and mostly gray in color. Another feature is that black sage tends to flower later than other species and the inflorescences persist throughout the winter.

      Artemisia nova is found on thin, usually rocky soil typically as a local dominant, the site being so harsh that few other shrubs grow with it. It occurs southeastern Oregon and northeastern California eastward to southwestern Montana, western Wyoming, Colorado and northwestern New Mexico. Lewis and Clark would have seen the plant just coming into flower in August of 1805 in Montana.

      Lewis might have seen three-tip sagebrush (Artemisia tripartita) after he left Clark at Traveler's Rest and headed for the Great Falls of the Missouri River. Today, one finds this aromatic shrub along the Blackfoot River where it occurs in rather moist sites (compared to the other sagebrushes) with lupines, Indian paintbrushes, and similar species. In this species the long, narrow leaves are deeply three-lobed with the lobes making up a third to a half of the length of the leaf-blade. This is most unlike the other sagebrushes along the Lewis and Clark Trail which are merely three-toothed (or entire) at the apex of the blade. Although it is not a feature Lewis could have observed, the leaves of Artemisia tripartita are deciduous so that they fall away in the winter, unlike the other species which have leaves that persist throughout the winter.

      Artemisia tripartita occurs from southern British Columbia to western Montana south to northern Nevada, Utah and Colorado. The plant was found by Thomas Nuttall in 1834 and named Artemisia trifida in 1841. Unbeknownst to Nuttall, that name had been use for a Russian species previously and therefore Per Axel Rydberg of the New York Botanical Garden gave it its present name in 1900.

      There are additional species of sagebrush in the American West south of the route taken by Lewis and Clark. Like those mentioned above, several have traditional medicinal uses for Native Americas. More and more species are coming into cultivation. The distinctive odor of sagebrush on a hot afternoon is soothing to many westerners. For many it is a natural form of aroma therapy.