6. Artemisia dracunculus L. (tarragon, silky wormwood)

A. cernua Rydb.

A. glauca Pall. ex Willd.

A. dracunculus ssp. dracunculina (S. Watson) H.M. Hall & Clem.

A. glauca var. dracunculina (S. Watson) Fernald

A. dracunculus ssp. glauca (Pall. ex Willd.) H.M. Hall & Clem.

Pl. 225 e, f; Map 946

Plants perennial herbs, with short rhizomes or somewhat woody rootstocks, variously not or slightly to strongly aromatic when bruised. Stems 40–150 cm long, erect or ascending, glabrous or more commonly sparsely to moderately pubescent with short, curly hairs, also minutely glandular. Leaves 1–8 cm long, short-petiolate to sessile, lacking stipulelike lobes or teeth at the base. Leaf blades mostly unlobed or the larger ones sometimes with 1(2) pair(s) of slender, ascending lobes toward the base, narrowly linear to lanceolate in outline, the ultimate segments or lobes 0.5–2.5(–4.0) mm wide, narrowly linear and threadlike with the margins curled under or slightly broader but still linear and relatively flat, sharply pointed at the tip, both surfaces glabrous or less commonly sparsely pubescent with short, curly hairs, also minutely glandular. Inflorescences appearing as open, leafy panicles, the branches spicate with relatively densely spaced, sessile to very short-stalked heads or less commonly narrowly racemose with more loosely spaced, longer-stalked heads. Heads with the central florets staminate and not producing fruits, only the marginal florets perfect (or rarely only pistillate) and developing fruits. Involucre 2.0–3.5 mm long, the bracts in 2 or 3 overlapping rows, the main body linear to oblong-elliptic, glabrous but minutely glandular, with broad, thin, transparent margins and tip, these glabrous. Receptacle naked. Corollas 1.2–2.0 mm long (those of the fertile florets shorter than those of the staminate ones). Fruits 0.5–0.8 mm long, more or less obovoid, finely and sometimes faintly 8–10-nerved, tan to grayish brown, shiny. 2n=18. June–October.

Uncommon in northwestern Missouri (Wisconsin to Texas west to Alaska, Washington, and California; Canada, Europe, Asia; introduced sporadically in the northeastern U.S.). Loess hill prairies, margins of lakes, and glades; also roadsides and open, sandy, disturbed areas.

In cultivation, this species is known as tarragon. It has a long history of use as a flavoring in soups and other foods. It also is cultivated occasionally as an ornamental foliage plant in gardens. Steyermark (1963) reported a noncultivated occurrence from Clark County, but the voucher specimen could not be located during the present study. It seems possible that the species might have occurred on the sandy terraces of the Des Moines River, and it should be searched for in that area. Statewide, the species apparently has not been collected since 1934, and it may have become extirpated from the Missouri portion of its range.

The taxonomy of this circumboreal complex needs further study. The names A. dracunculus and A. glauca both were originally described based upon Siberian materials, and the North American plants were long known under later names like A. cernua Rydb. and A. dracunculoides Pursh, which were based upon American specimens. The interpretation of Hall and Clements (1923) that plants of the New World and Old World should be classified as a single species was ignored by many later botanists, perhaps in part because Hall and Clements erected an overly complicated infraspecific classification whose subspecies and varieties were not easily separable in the keys. Some of the problems may be due to apparent limited morphological intergradation between A. dracunculus and A. campestris in the southern Great Plains (Barkley, 1986). Most authors today sidestep the issue by choosing not to treat any of the subspecies or varieties. For those users of the present work who wish to attempt to subdivide A. dracunculus, the Missouri materials more or less fall along a gradient between the following two extremes. The rare ssp. dracunculina tends to have slightly smaller heads that have longer stalks and are grouped into more open inflorescences, whereas the more common ssp. glauca has slightly larger heads that are sessile or short-stalked and grouped into somewhat more congested inflorescences.