[+][+][+][+] Leaves all or most of them opposite, 3-nerved (faintly in n. 15).
[++] Heads very small (about 4´´ broad); rays 5–8; scales few, short, irregularly imbricated, the outer with spreading foliaceous pointed tips; stems smooth.
14. H. parviflòrus, Bernh. Stem 3–6° high, with numerous slender branches above; leaves thin, ovate-lanceolate, taper-pointed, somewhat serrate, petioled, rough above, pale and puberulent beneath; peduncles slender, rough; scales ovate and ovate-lanceolate, ciliate. (H. microcephalus, Torr. & Gray.)—Thickets, Penn. to Ill., and southward.
15. H. lævigàtus, Torr. & Gray. Stem slender (1–6° high), simple or sparingly branched, glaucous, glabrous throughout, as well as the slightly serrate lanceolate leaves which are usually narrow and attenuate to the base.—Dry soil, Alleghany Mts., and southward.
[++][++] Heads larger; rays usually over 10; spreading by creeping root stocks.
[=] Leaves sessile or subsessile to short-petiolate, serrulate or entire.
16. H. doronicoìdes, Lam. Finely pubescent and roughish, 3–7° high; leaves sessile, ovate-oblong, acute, triply-nerved above, the broadly cuneate base, serrulate; scales loose, attenuate, mostly 6–8´´ long, hairy. (H. cinereus, var. Sullivantii, Torr. & Gray.)—Dry ground, Ohio to Mo.
17. H. divaricàtus, L. Stem simple or forked and corymbed at the top (1–4° high), smooth below; leaves all opposite and divaricate, ovate-lanceolate, 3-nerved from the rounded or truncate sessile base, tapering gradually to a sharp point (3–6´ long), serrate, thickish, rough both sides; scales narrowly lanceolate, attenuate, ciliate, equalling the disk; rays 8–12.—Thickets and barrens; common.—Disk 6´´ wide; rays 1´ long.
18. H. hirsùtus, Raf. Stem simple or forked above, stout (1–4° high), bristly-hairy; leaves all shortly petioled, ovate-lanceolate, gradually pointed, slightly serrate, rounded or obtuse at the base, very rough above, usually rough-hairy beneath; scales ovate-lanceolate, pointed, equalling the disk; rays about 12.—Dry plains, Ohio to Wisc., and southward.
19. H. strumòsus, L. Stem (3–6° high) very smooth below, often glaucous; leaves ovate-lanceolate, tapering gradually to a point, or the lower ovate and acute, abruptly contracted into short margined petioles, rough above, whitish and naked or minutely downy underneath; scales broadly lanceolate with spreading tips, ciliate, equalling the disk; rays 9–15.—Var. móllis, Torr. & Gray, has the leaves downy underneath, often subcordate, the scales looser and more attenuate.—River-banks and low copses; common, especially westward.