24. A. Lindleyànus, Torr. & Gray. Rather stout, 1--2° high, sparsely pubescent or nearly glabrous; _radical and lowest leaves ovate, moderately or obscurely cordate_, the uppermost sessile and pointed at both ends; _heads larger_, rather few in a loose thyrse or panicle, _the linear-attenuate scales looser and less imbricated_; rays pale violet.--Lab. to L. Superior; Lisbon, N. H. (_C. E. Faxon_), and Mt. Desert (_Rand_). [*] 6. _Without heart-shaped petioled leaves, the radical and lower all acute or attenuate at base; not glandular nor viscid, nor silky-canescent._ [+] _Smooth and glabrous throughout (or nearly so, except forms of n. 29), and usually pale and glaucous; involucral scales closely imbricated, firm and whitish-coriaceous below, green-tipped; leaves firm, usually entire._ [++] _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.