7. Artemisia frigida Willd. (prairie sagewort)

Pl. 226 h, i; Map 947

Plants perennial herbs, forming low mounds or mats from woody rootstocks, often producing short vegetative stems in addition to the flowering ones, strongly aromatic when bruised. Stems 8–40(–60) cm long, ascending from spreading bases, densely pubescent with grayish white, woolly or felty hairs, these hiding the minute glands. Leaves 0.5–1.5 cm long, short-petiolate or the uppermost leaves sessile, often with a pair of slender, stipulelike lobes or leaflets at the base. Leaf blades mostly 2 or 3 times ternately compound or deeply lobed, narrowly oblanceolate to broadly obovate in outline, the ultimate segments or lobes 0.5–2.0 mm wide, narrowly linear and often threadlike, mostly sharply pointed at the tip, the margins entire and usually rolled under, both surfaces densely pubescent with woolly or felty hairs, also minutely glandular. Inflorescences appearing paniculate or racemose, ranging from narrow and spikelike with short, densely flowered branches to less commonly more open with longer, ascending branches, the heads sessile and/or very short-stalked. Heads with the central florets perfect and the marginal florets usually pistillate, thus all of the florets potentially producing fruits. Involucre 2–3 mm long, the bracts in 2 or 3 overlapping rows, the often indistinct main body linear to oblong-elliptic, moderately to densely woolly-hairy and minutely glandular, the innermost with broad, thin, transparent margins and tip, these also hairy. Receptacle with relatively long, bristly hairs between the florets. Corollas 1.2–1.6 mm long. Fruits 0.7–1.0 mm long, narrowly ellipsoid-obovoid to nearly cylindrical, faintly lined, somewhat flattened, reddish brown to brown, shiny. 2n=18. July–September.

Introduced, known thus far from historical collections from Jackson County and a somewhat more recent specimen collected in St. Francois County (western U.S. [including Alaska] west to Wisconsin and Texas; Canada; introduced farther east). Railroads, roadsides, and open, disturbed areas.