3. Artemisia L. (wormwood, sage, mugwort)

Plants annual, biennial, or perennial herbs (shrubs elsewhere), sometimes from a woody rootstock, weakly to strongly aromatic, glabrous or sparsely to densely hairy. Stems erect or ascending, branched or unbranched, finely ridged. Leaves alternate and sometimes also basal, sessile or short-petiolate (the lowermost leaves usually long-petiolate in A. absynthium), sometimes with slightly broadened, more or less clasping bases. Leaf blades entire or variously lobed or compound, glandular and otherwise glabrous to variously hairy, the blade or lobes with 1 to several veins, these sometimes difficult to observe. Inflorescences terminal and often also axillary, spikes or racemes, sometimes grouped into terminal panicles, these usually elongate or pyramidal, the branches spicate, racemose, or sometimes reduced to small clusters sessile along the main axis, bractless or with bracts subtending the heads. Heads discoid, all of the florets perfect (the marginal florets sometimes only pistillate) and potentially producing fruits, or the marginal florets perfect and the central florets only staminate and not producing fruits. Involucre broadly ovoid to nearly cylindrical, the bracts more or less in 2–4 overlapping series, the outer ones somewhat shorter, narrowly ovate to linear, sharply pointed at the tip, variously glabrous or hairy and glandular, often with a green or brown midvein or subapical area, otherwise grayish tan to brown, usually flat, at least the innermost usually with the margins thin and papery. Receptacle usually strongly convex at flowering, not conspicuously elongating at fruiting, solid, naked or less commonly densely bristly-hairy. Disc florets numerous, the corolla yellow or greenish yellow, sometimes purplish-tinged, minutely glandular, the 5 lobes without resin canals, persistent, the tube not flattened toward the tip but sometimes slightly oblique at the tip, not becoming swollen at fruiting. Pappus absent. Fruits ellipsoid to ellipsoid-obovoid, less commonly nearly cylindrical, not or only slightly flattened, often somewhat asymmetric at the base, the tip often slightly obliquely truncate, relatively strongly 5–10-ribbed to inconspicuously nerved or lined, the surface otherwise usually glabrous, tan to brown. About 350 species, nearly worldwide.

The species of sagebrush in the western states are all shrubby members of the genus Artemisia. Various species have long been cultivated as ornamentals for their silvery foliage. The name wormwood comes from the use of some species in medieval times to treat intestinal worms. Various other species have been used as spices and flavorings. Because the genus is mainly wind-pollinated, some species, particularly A. annua, are considered bad hay fever plants.