[*] 3. Leaves whitened, silvery-silky both sides, all sessile and entire, mucronulate; involucre imbricated in 3 to several rows; rays showy, purple-violet.
14. A. serìceus, Vent. Stems slender, branched; leaves silver-white, lanceolate or oblong, heads mostly solitary, terminating the short branchlets; scales of the globular involucre similar to the leaves, spreading, except the short coriaceous base; achenes smooth, many-ribbed.—Prairies and dry banks, Wisc. and Minn. to Ky., and southward.—Heads large; rays 20–30.
15. A. cóncolor, L. Stems wand-like, nearly simple; leaves crowded, oblong or lanceolate, appressed, the upper reduced to little bracts; heads in a simple or compound wand-like raceme; scales of the obovoid involucre closely imbricated in several rows, appressed, rather rigid, silky, lanceolate; achenes silky.—Dry sandy soil near the coast, R. I., N. J., and southward.—Plant 1–3° high, with the short leaves 1´ or less in length, grayish-silky both sides.
[*] 4.Leaves entire, the lower not heart-shaped, the cauline all with sessile and cordate-clasping base, the auricles generally meeting around the stem.
16. A. pàtens, Ait. Rough-pubescent; stem loosely panicled above (1–3° high), with widely spreading branches, the heads mostly solitary, terminating slender branchlets; leaves oblong-lanceolate or ovate-oblong, often contracted below the middle, rough, especially above and on the margins; scales of the minutely roughish involucre with spreading pointed tips; achenes silky.—Var. phlogifòlius, Nees, is a form of shady moist places, with larger and elongated thin scarcely rough leaves, downy underneath, sometimes a little toothed above, mostly much contracted below the middle.—Dry ground; common, Mass. to Minn., and southward. Heads ½´ broad, with showy deep blue-purple rays.
[*] 5 Lower leaves heart-shaped and petioled; no glandular or viscid pubescence; heads with short and appressed green-tipped scales (except in n. 16 and 23), mostly small and numerous, racemose or panicled.
[+] Heads middle-sized, with many rays, and squarrose foliaceous involucre.
17. A. anómalus, Engelm. Somewhat pubescent and scabrous; stems slender (2–4° high), simple or racemose-branched above; leaves ovate or ovate-lanceolate, pointed, entire, the upper small and almost sessile; scales of the hemispherical involucre imbricated in several rows, appressed, with linear spreading leafy tips; achenes smooth.—Limestone cliffs, W. Ill. and Mo. to Ark.—Rays violet-purple.
[+][+] Rays 10–20; involucral scales appressed or erect.
[++] Leaves entire or slightly serrate; heads middle-sized; rays bright-blue.