1. Artemisia absinthium L. (absinthe, common wormwood)

Pl. 226 a, b; Map 941

Plants perennial herbs, with stout, woody taproots, strongly aromatic when bruised. Stems 35–120 cm long, erect or ascending, moderately to densely pubescent with silky hairs and minutely glandular when young, sometimes becoming nearly glabrous with age. Leaves 1–20 cm long, the basal and lower to median leaves relatively long-petiolate, the upper leaves short-petiolate to sessile, lacking stipulelike lobes or teeth at the base. Leaf blades mostly 2–3 times pinnately compound or deeply lobed and ovate in outline, the uppermost unlobed or few-lobed and linear to narrowly elliptic in outline, the main leaves with 3 or 5 primary lobes, the ultimate segments or lobes 1–3 mm wide, narrowly oblong to linear but not threadlike, rounded to sharply pointed at the tip, both surfaces densely pubescent with silky to woolly hairs when young, the upper surface sometimes becoming nearly glabrous at maturity, also minutely glandular. Inflorescences appearing as open, leafy panicles, the branches spicate or narrowly racemose with more or less loosely spaced heads. Heads with the central florets perfect and the marginal florets pistillate, thus all of the florets potentially producing fruits. Involucre 2–3 mm long, the bracts in 2 or 3 overlapping rows, the main body oblong-elliptic to broadly elliptic, densely silky-hairy and minutely glandular, with broad, thin, transparent margins and tip, these usually cobwebby-hairy along the edge. Receptacle with relatively long, bristly hairs between the florets. Corollas 1.2–1.8 mm long. Fruits 0.7–1.0 mm long, more or less obovoid, faintly lined, tan to grayish brown, shiny. 2n=18. July–September.

Introduced, known thus far only from the city of St. Louis (native of Europe, Asia, introduced widely in northern North America south to Oregon, Utah, and South Carolina). Railroads and open, disturbed areas.

This species was reported for Missouri by Mühlenbach (1979) during his botanical research in the St. Louis railyards. It is cultivated sporadically as a garden ornamental around the state, but it is unlikely to escape widely, as Missouri is at the southern edge of its climatic tolerance.

Wormwood is an active ingredient in absinthe, an alcoholic beverage that also usually contains flavorings such as anise and fennel (to mask the innate bitterness of the Artemisia). This liquor was popular in nineteenth-century Europe (and elsewhere) but has since been banned as a hazardous narcotic in many countries. The reputation of absinthe for inducing drunkenness, euphoria, and hallucinations (sometimes also psychosis and schizophrenia) is in part because keeping compounds in the wormwood extract dissolved requires a high percentage of alcohol in the solution. The principal mind-altering agent, thujone, is a neurotoxic terpenoid that can cause kidney failure in high doses.