1 Disk flowers functionally sterile (with abortive ovaries); corollas subglobose; fresh plants either not aromatic or with a tarragon odor; [subgenus Dracunculus].

  2 Plant a shrub; cypselae 0.2-0.5 mm long

  2 Plant an herb or subshrub; cypselae 0.5-1 mm long.

    3 Leaves lobed; leaf surfaces glabrous to densely pubescent; fresh plants not aromatic or faintly so (but not of tarragon); plant a biennial

    3 Leaves mostly entire (some basal leaves sometimes irregularly lobed; leaf surfaces glabrous (or glabrescent); fresh plants usually with a tarragon odor; perennial from a stout rhizome

1 Disk flowers fertile (with normal ovaries); corollas funnel-shaped; fresh plants variously aromatic or not (but not with a tarragon odor).

      4 Receptacle bearing dense long hairs between the flowers; fresh plants strongly aromatic; [subgenus Absinthium]

      4 Receptacle not pubescent; fresh plants variously aromatic or not; [subgenus Artemisia].

        5 Leaves green, essentially glabrous on the lower surface; annuals or biennials from a taproot; plants lacking nonflowering shoots.

          6 Inflorescence obviously paniculate, the branches evident, the heads on slender peduncles; involucres 1-2 mm high and 1-2 mm wide; fresh plants sweet-aromatic

          6 Inflorescence spike-like, the heads crowded and hiding the branches; involucres 2-3 mm high, 2-3 mm wide; fresh plants not aromatic

        5 Leaves tomentose on the lower surface, densely so in many species; perennials from a branched rhizome or woody caudex; plants with nonflowering shoots.

             7 Principal leaves 2-3-pinnatifid, the terminal segments < 1.5 mm wide; plant a shrub or suffrutescent herb.

               8 Leaves white-tomentose above, 1-3 cm long

             7 Principal leaves entire to 2-pinnatifid, the terminal segments > 2 mm wide; plant an herb (sometimes somewhat woody at the base).

                 9 Involucres 6-10 mm high; disk corollas 3.2-4 mm long

                 9 Involucres 2.5-5 mm high; disk corollas 1-3 mm long.

                   10 Leaves 2-pinnatifid; leaves with 1-2 stipule-like lobes at the base

                     11 Plants always with well-developed rhizomes and stolons, thus forming dense colonial patches; middle leaves with terminal (untoothed) leaf segment usually > 3 cm long; stem with central white pith region occupying approx. 1/3 of total (green and white) pith diameter; inflorescence often well-branched; plants typically flowering later (late summer, autumn)

                     11 Plants almost always non-rhizomatous (instead tufted perennials), although sometimes with short rhizomes thus, several stems usually arising from one concentrated point at ground level; middle leaves with terminal (untoothed) leaf segment usually < 3 cm long; stem with central white pith region occupying approx. 4/5 of total (green and white) pith diameter; inflorescence often sparsely branched; plants typically (though not always) flowering earlier (late spring, summer), although sometimes with a second flowering period in autumn

                   10 Leaves entire to 1-pinnatifid; leaves lacking stipule-like lobes at the base.

                       12 Leaf blades 0.1-3 cm long; deeply pinnatifid with sinuses greater than ½ the blade width; [TX northwards, southwards, and westwards]

                       12 Leaf blades 1.5-11 cm long; usually shallowly lobed with sinuses less than ½ the blade width; [collectively widely distributed].

                          13 Leaves margins planar; stems gray to white tomentose; [widely distributed in our region]

                          13 Leaves margins revolute; stems sparsely hairy to glabrous; [OK and TX southwards and westwards]