Biennials or perennials, (10-)30-80(-150) cm, faintly aromatic; taprooted, caudices branched. Stems usually 1-5, turning reddish brown, (often ribbed) tomentose or glabrous. Leaves persistent or deciduous, mostly basal; basal blades 4-12 cm, cauline gradually reduced, 2-4 × 0.5-1.5 cm, 2-3-pinnately lobed, lobes linear to narrowly oblong, apices acute, faces densely to sparsely white-pubescent. Heads (pedunculate) in (mostly leafless) paniculiform arrays. Involucres broadly turbinate, 2.5-3(-5) × 2-3.5(-7) mm. Phyllaries (margins scarious) glabrous or villous-tomentose. Florets: pistillate 5-20; functionally staminate 12-30; corollas pale yellow, sparsely hairy or glabrous. Cypselae oblong-lanceoloid, somewhat compressed, 0.8-1 mm, faintly nerved, glabrous. Artemisia campestris varies; each morphologic form grades into another. The present circumscription is conservative in that only three subspecies are recognized; the subspecies usually can be separated geographically as well as morphologically. Populations in western North America consist primarily of subsp. pacifica; east of the continental divide, plants are assigned to subsp. canadensis in northern latitudes and to subsp. caudata in southern latitudes.
Scarcely odorous biennial or perennial 1-10 dm from a taproot; basal lvs crowded, 2-10 cm (petiole included) נ0.7-4 cm, twice or thrice pinnatifid or ternate, with mostly linear or linear-filiform segments seldom over 2 mm wide, glabrous to sericeous or villous, persistent or deciduous; cauline lvs similar but smaller and less divided, the uppermost often ternate or simple; infl small and spike- like to diffuse and panicle-like; invol glabrous to densely villous-tomentose, 2-4.5 mm; disk-fls sterile, with abortive ovary; achenes subcylindric; 2n=18, 36. Open places, often in sandy soil; circumboreal, extending s. to Fla. and Ariz. July-Sept. A complex sp., composed of many races, the taxonomy still confused. Ssp. caudata (Michx.) H. M. Hall & Clem., a robust, mostly single-stemmed biennial (occasionally short-lived perennial) to 1 m or more tall, occurring on dunes and other very sandy places along the coast and irregularly inland throughout our range, is well marked. Typically it is glabrous or subglabrous. A more hairy, scarcely definable phase of ssp. caudata, which occurs on the n. Great Plains and enters our range along the Great Lakes, has been called A. forwoodii S. Watson, but has no name under A. campestris. All or nearly all the rest of our material of A. campestris belongs to a phase that has been called A. canadensis Michx., or A. campestris var. canadensis (Michx.) S. L. Welsh. It is a ±multicipital perennial, seldom 6 dm, with fewer and often larger heads than ssp. caudata, occurring from Vt. and Minn. northward, often in the mts. In the broad sense the var. canadensis may be considered a part of A. campestris ssp. borealis (Pall.) H. M. Hall & Clem.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.