13. A. modéstus, Lindl. Pubescent or glabrate; stem slender, simple, with few large heads terminating slender branchlets; leaves lanceolate, very acute, narrowed to a sessile base, sparingly serrate or serrulate; scales linear-attenuate, equal, mostly herbaceous; rays blue.--N. Dak. and westward. [*] 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._