10. Artemisia vulgaris L. (common mugwort)

A. vulgaris var. glabra Ledeb.

A. vulgaris var. latiloba Ledeb.

Pl. 226 c, d; Map 950

Plants perennial herbs, with rhizomes, strongly aromatic when bruised. Stems 30–150(–200) cm long, erect or ascending from sometimes spreading bases, glabrous or sparsely hairy toward the tip, also minutely glandular. Leaves 1–10 cm long, short-petiolate to sessile, usually with 1 or 2 pairs of small, stipulelike lobes at the base. Leaf blades 1 or 2 times pinnately lobed with 1–3 pairs of primary lobes, the uppermost merely toothed or entire, linear to ovate or obovate in outline, the primary lobes linear to oblong or narrowly fan-shaped in outline, the margins toothed or lobed (except those of the uppermost leaves), the ultimate segments or lobes 2–11 mm wide (mostly more than 2 mm wide), the margins flat or those of the upper leaves curled under, bluntly to more commonly sharply pointed at the tip, the upper surface glabrous, the undersurface densely pubescent with woolly to felty hairs, also minutely glandular. Inflorescences appearing as open, leafy panicles, the branches spicate with usually relatively densely spaced, sessile to short-stalked heads. Heads with the central florets perfect and the marginal florets pistillate or less commonly perfect, thus all of the florets potentially producing fruits. Involucre 2.5–4.0 mm long, the bracts in 3 or 4 overlapping rows, the often indistinct main body linear to oblong-elliptic, sparsely to densely woolly-hairy and minutely glandular, at least the innermost with relatively broad, thin, transparent margins and tip, these hairy or glabrous toward the tip. Receptacle naked. Corollas 2.0–2.8 mm long. Fruits 0.6–1.2 mm long, narrowly oblong-obovoid, not or very faintly lined, tan to yellowish brown, shiny. 2n=16 (unusual counts of 2n=18, 34, 36, 40, 54 also have been reported). July–October.

Introduced, uncommon and widely scattered, mostly in urban areas (northwestern U.S. including Alaska; Canada, Europe, Asia; introduced farther east in North America). Gardens, railroads, roadsides, and open, disturbed areas.

In Europe, this plant was used medicinally to treat intestinal worms and also as a natural insect repellant. Steyermark (1963) reported that overuse could lead to various pains, spasms, and other toxic effects. It has been cultivated in the United States in gardens for its attractive and aromatic foliage. The lower leaves can appear quite similar to those of some of the cultivated mums. Interestingly, some cultivated and escaped plants appear to produce few or no achenes in a given year.

Ling (1995) segregated plants with slightly larger heads and slightly shorter stems as A. indica Willd. (A. vulgaris var. kamtschatica Besser) and annotated some of the Missouri materials as representing this taxon. However, there appears to be too much variation across the range of A. vulgaris to allow the segregation of species or even subspecies. Also, the few Missouri specimens in question seem to fit Ling’s concept of A. vulgaris in the strict sense better than they do A. indica.