[++] Rays violet or blue; scales rather abruptly green-tipped; leaves on the branchlets reduced to rigid subulate bracts.
25. A. turbinéllus, Lindl. Stem slender, 3° high, paniculately branched; leaves oblong to narrowly lanceolate, tapering to each end, with rough margins; involucre elongated-obconical or almost club-shaped (½´ long); the scales linear, with very short and blunt green tips; rays violet-blue; achenes nearly smooth.—Dry hills, etc., Ill., Mo., and southwestward.—Well-marked and handsome.
26. A. læ̀vis, L. Stouter, 2–4° high; heads in a close panicle; leaves thickish, lanceolate or ovate-lanceolate, chiefly entire, the upper more or less clasping by an auricled or heart-shaped base; scales of the short-obovoid or hemispherical involucre with short abrupt green tips; rays sky-blue; achenes smooth.—Borders of woodlands; common. A variable and elegant species.
27. A. virgàtus, Ell. Slender, strict and simple, with few or several racemose or terminal heads, like those of the last; leaves lanceolate or linear, the lower usually long and narrow.—S. W. Va., and southward.
28. A. concínnus, Willd. Not glaucous, slender, 1–3° high; leaves lanceolate, mostly somewhat serrate, the lowest spatulate-lanceolate on winged petioles; heads smaller than in the preceding, numerous, panicled; rays violet.—Rare; Penn. and southward.
[++][++] Rays white or turning purplish; scales narrow, subulately green-tipped; leaves mostly narrow, narrowed at base, on the branchlets lax and attenuate.
29. A. polyphýllus, Willd. Often tall (4 or 5° high), with virgate branches; cauline leaves narrowly lanceolate or linear, 4 or 5´ long; heads paniculate; scales lanceolate-subulate, the outermost much shorter; rays 4´´ long.—N. Vt. to Wisc., and southward. Heads larger and flowering earlier than the next.
30. A. ericoìdes, L. Smooth or sparingly hairy (1–3° high); the simple branchlets or peduncles racemose along the upper side of the wand-like spreading branches; lowest leaves oblong-spatulate, sometimes toothed; the others linear-lanceolate or linear-awl-shaped; heads 3´´ high or less; involucral scales often nearly equal, with attenuate or awl-shaped green tips.—Dry open places, S. New Eng. to Minn., and southward.—Var. villòsus, Torr. & Gray, is a hairy form, often with broader leaves; chiefly in the Western States.—Var. pusíllus, Gray, is a dwarf slender and glabrous form of the barrens of Lancaster, Penn. (Porter), with very narrow or filiform leaves and very small few-flowered heads.—Var. Prínglei, Gray, a low strict form, with few erect branches and rather small heads. About Lake Champlain.
[+][+] Hoary-pubescent or hirsute; herbaceous tips of the involucral scales squarrose or spreading; cauline leaves small, linear, entire, scarcely narrowed at the sessile or partly clasping base; heads numerous, small, racemose.
31. A. amethýstinus, Nutt. Tall (2–5° high), upright, much branched, puberulent or somewhat hirsute; leaves not rigid; heads 3´´ high, the tips of the scales merely spreading; rays light clear blue.—Moist grounds, E. Mass. to Ill. and Iowa. With the habit of n. 11.