4. Artemisia campestris L. ssp. caudata (Michx.) H.M. Hall & Clem. (western sagewort, wild wormwood)

A. caudata Michx.

A. campestris L. var. caudata (Michx.) E.J. Palmer & Steyerm.

Pl. 225 g–i; Map 944

Plants biennial (rarely short-lived perennial) with taproots, not or only slightly aromatic when bruised. Stems 30–120 cm long, erect or ascending, glabrous at maturity but minutely glandular. Leaves 1–16 cm long, the basal and lowermost leaves usually withered by flowering time, long-petiolate, the main leaves mostly short-petiolate, lacking stipulelike lobes or leaflets at the base. Leaf blades 1–3 times pinnately compound or deeply lobed (those of the uppermost leaves occasionally unlobed), lanceolate to ovate or obovate in outline, the main leaves with 3–7 primary lobes, the ultimate segments or lobes 0.5–1.5(–2.0) mm wide, narrowly linear (threadlike) and often elongate, mostly sharply pointed at the tip, the margins entire, both surfaces glabrous but minutely glandular at maturity, sometimes sparsely to moderately pubescent with fine, cobwebby hairs when young. Inflorescences appearing as open, leafy panicles, the branches narrowly racemose with more or less loosely spaced, stalked heads. Heads with the central florets staminate and not producing fruits, only the marginal florets perfect and developing fruits. Involucre 2.5–4.0 mm long, the bracts in 3 or 4 overlapping rows, the main body elliptic-ovate to ovate, glabrous but minutely glandular, with broad, thin, transparent margins and tip, these glabrous. Receptacle naked, without bristly hairs. Corollas 0.7–1.7 mm long (those of the fertile florets shorter than those of the staminate ones). Fruits 0.7–0.9 mm long, narrowly oblong-obovoid, faintly lined, somewhat flattened, reddish brown to brown, shiny. 2n=18, 36. July–October.

Uncommon in the east-central portion of the Ozark Division and in St. Louis and adjacent counties (eastern U.S. west to Wyoming and New Mexico; Canada). Banks of streams and rivers, tops and ledges of sandstone bluffs; also railroads and open, sandy, disturbed areas.

Artemisia campestris is a circumboreal taxon that has been split into a number of intergrading subspecies and varieties (Hall and Clements, 1923; Cronquist, 1955). The ssp. campestris is confined to the Old World. The eastern ssp. caudata differs from other North American members of the complex in its biennial (vs. perennial) habit, however, a few of the Missouri specimens show development of new overwintering rosettes as offshoots from the base of a flowering stem. Within ssp. caudata, plants from the Great Plains tend to be more densely and persistently hairy than those from farther east (including Missouri).