Shrubs, 40-200(-300) cm (herbage gray-haired), aromatic; not root-sprouting (trunks relatively thick). Stems gray-brown, glabrate (bark gray, exfoliating in strips). Leaves persistent, gray-green; blades usually cuneate, (0.4-)0. 5-3.5 × 0.1-0.7 cm, 3-lobed (lobes to 1/3 blade lengths, 1.5+ mm wide, rounded), faces densely hairy. Heads (usually erect, on slender peduncles) in paniculiform arrays 5-30 × 1-6 cm. Involucres lanceolate, (1-)1.5-4 × 1-3 mm. Phyllaries oblanceolate to widely obovate, densely tomentose. Florets 3-8; corollas 1.5-2.5 mm, glabrous. Cypselae 1-2 mm, hairy or glabrous, glandular. Artemisia tridentata has undergone considerable taxonomic revision in the past century and circumscription of subspecies remains a topic of considerable controversy. Workers in the field should be aware of the morphologic variation within the subspecies across the range of the species (i.e., approximately from the Sierra Nevada in the west to the plains of the Rocky Mountains in the east). Because rangeland managers and conservationists can often identify local morphologic and chemical races based on grazing or habitat preferences of wildlife and domestic animals, some impetus exists to further subdivide the subspecies within A. tridentata at the varietal level. This treatment of the species complex remains conservative in light of the need for further study. As to chemical differences among the subspecies, aroma is often used to distinguish subspecies in the field. Volatile resins in the plants are strongly aromatic and, when crushed, leaves have very distinctive (although not easily described) aromas.
Plant: Shrub < 30 dm, from thick trunk, gray-hairy; stems generally glabrous Leaves: 1-3(6) cm, generally wedge-shaped, generally 3(0-5)-toothed at tip, often in axillary clusters, persistent, gray-green, densely hairy INFLORESCENCE: primary inflorescence a head, each resembling a flower; heads 2-2.5 mm diam, generally erect; phyllaries oblanceolate to widely obovate, densely tomentose, margins ± transparent Flowers: Pistillate flowers 0; Disk flowers 4-6; corollas < 2 mm, pale yellow; anther tips acute to awl-shaped; style branches flat, fringed or blunt (sometimes simple, tack-shaped in staminate flowers) Fruit: achenes, 1-2 mm, glandular or hairy Misc: Dry soils, valleys, slopes; 300-3000+ m.