Var. rigidulus, Gray. Low, with more rigid and hispidulous scabrous leaves.--In drier places, Ill., Wisc., and southwestward.

12. A. Nvae-angliae, L. _Stem stout, hairy_ (3--8 high), corymbed at the summit; _leaves very numerous, lanceolate, entire, acute, auriculate-clasping, clothed with minute p.u.b.escence_, 2--5' long; _scales nearly equal, linear-awl-shaped, loose, glandular-viscid_, as well as the branchlets; rays violet-purple (in var. RSEUS rose-purple), very numerous; achenes hairy.--Moist grounds; common.--Heads large. A peculiar and handsome species.

13. A. modestus, Lindl. p.u.b.escent 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. serceus, 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. concolor, 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. patens, Ait. Rough-p.u.b.escent; 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. PHLOGIFLIUS, 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, Ma.s.s. to Minn., and southward. Heads ' broad, with showy deep blue-purple rays.

[*] 5 _Lower leaves heart-shaped and petioled; no glandular or viscid p.u.b.escence; 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. anomalus, Engelm. Somewhat p.u.b.escent 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._

18. A. azureus, Lindl. Stem rather rough, erect, racemose-compound at the summit, the branches slender and rigid; _leaves rough, the lower ovate-lanceolate or oblong, heart-shaped, on long often hairy petioles; the others lanceolate or linear, sessile_, on the branches awl-shaped; involucre inversely conical.--Copses and prairies, western N. Y., and Ohio to Minn., and southwestward. Involucre much as in A. laevis, but smaller and slightly p.u.b.escent.

19. A. Shortii, Hook. Stem slender, spreading, nearly smooth, bearing very numerous heads in racemose panicles; _leaves smooth above, minutely p.u.b.escent underneath, lanceolate or ovate-lanceolate, elongated_, tapering gradually to a sharp point, _all but the uppermost more or less heart-shaped at base, and on naked petioles_, none clasping; involucre bell-shaped.--Cliffs and banks, Ohio to Ill., and southward.--A pretty species, 2--4 high; leaves 3--5' long.

20. A. undulatus, L. Pale or somewhat h.o.a.ry with close p.u.b.escence; stem spreading, bearing numerous heads in racemose panicles; _leaves ovate or ovate-lanceolate, with wavy or slightly toothed margins, roughish above, downy underneath_, the lowest heart-shaped on margined petioles, the others _abruptly contracted into short broadly winged petioles which are dilated and clasping at the base_, or directly sessile by a heart-shaped base; involucre obovoid, the scales less rigid.--Dry copses; common.

[++][++] _Leaves conspicuously serrate; heads small; rays pale blue or nearly white._

21. A. cordiflius, L. Stem much branched above, _the spreading or diverging branches bearing very numerous panicled heads_; lower leaves all heart-shaped, on slender and mostly naked ciliate petioles; _scales of the inversely conical involucre all appressed and tipped with very short green points, obtuse or acutish_.--Woodlands; very common.--Heads profuse, but quite small. Varies with the stem and leaves either smooth, roughish, or sometimes hairy, also with the leaves all narrower.

Apparent hybrids with n. 35 also occur.

22. A. sagittiflius, Willd. Stem rigid, erect, with _ascending branches bearing numerous racemose heads_; leaves ovate-lanceolate, pointed; the lower heart-shaped at base, on margined petioles; the upper lanceolate or linear, pointed at both ends; _scales of the oblong involucre linear, tapering into awl-shaped slender and loose tips_.--Dry ground, N. Y. and Penn. to Ky., and northward.--Green, but usually more or less hairy or downy; the heads rather larger than in the last, almost sessile.

23. A. Drummondii, Lindl. Pale with fine gray p.u.b.escence; _leaves cordate to cordate-lanceolate, mostly on margined petioles_, the uppermost lanceolate and sessile; _scales acute or acutish_.--Pa.s.sing into the last. Open ground, etc., Ill. to Minn. and Kan.

24. A. Lindleya.n.u.s, Torr. & Gray. Rather stout, 1--2 high, spa.r.s.ely p.u.b.escent 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. turbinellus, 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 ('

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. lae'vis, 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. virgatus, 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. concinnus, 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. polyphllus, 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. ericodes, 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.

VILLSUS, Torr. & Gray, is a hairy form, often with broader leaves; chiefly in the Western States.--Var. PUSiLLUS, 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.

PRiNGLEI, Gray, a low strict form, with few erect branches and rather small heads. About Lake Champlain.

[+][+] _h.o.a.ry-p.u.b.escent 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. amethstinus, Nutt. Tall (2--5 high), upright, much branched, p.u.b.erulent or somewhat hirsute; leaves not rigid; heads 3" high, the tips of the scales merely spreading; rays light clear blue.--Moist grounds, E. Ma.s.s. to Ill. and Iowa. With the habit of n. 11.

32. A. multiflrus, Ait. Pale or h.o.a.ry with minute close p.u.b.escence (1 high), much branched and bushy; the heads much crowded on the spreading racemose branches; leaves rigid, crowded, spreading, with rough or ciliate margins, the uppermost pa.s.sing into the spatulate obtuse scales; heads 2--3" long; rays white or rarely bluish, 10--20.--Dry sandy soil; common.

[+][+][+] _Scales glabrous, closely imbricated (the outer regularly shorter), not coriaceous, with short appressed green tips; branches slender, divaricate or divergent; leaves lanceolate to subulate; heads small (2--3" high) and numerous._

[++] _Heads scattered, terminating minutely foliose slender branchlets._

33. A. dumsus, L. Smooth or nearly so, 1--3 high; leaves linear or the upper oblong, crowded, entire, with rough margins; scales linear spatulate, obtuse, in 4--6 rows.--Thickets; common.--A variable species, loosely branched, with small leaves, especially the upper, and an obconical or bell-shaped involucre, with more abrupt green tips than any of the succeeding. Rays pale purple or blue, larger than in n. 34. Runs into several peculiar forms.

[++][++] _Heads racemosely unilateral upon very short minutely leafy branchlets._

34. A. vimineus, Lam. _Smooth or smoothish_, 2--5 high, bushy; leaves linear or narrowly lanceolate, elongated, the larger ones remotely serrate in the middle with fine sharp teeth; _scales of the involucre narrowly linear, acute or acutish_, in 3 or 4 rows. (A. Tradescanti, of previous ed.)--Var. FOLIOLSUS, Gray, has linear entire leaves, the ascending branches with more scattered paniculate heads.--Moist banks; very common.--Heads very numerous, and usually crowded, smaller than in the last. Rays white or nearly so.

35. A. diffusus, Ait. _More or less p.u.b.escent_, much branched; _leaves_ lanceolate or oblong-lanceolate, tapering or pointed at each end, _sharply serrate in the middle; scales of the involucre linear, acute or rather obtuse_, imbricated in 3 or 4 rows. (A. miser, of previous ed.)--Thickets, fields, etc.; very common, and extensively variable.

Leaves larger than in either of the preceding (2--5'); the involucre intermediate between them, as to the form of the scales. Rays mostly short, white or pale bluish-purple.--Var. THYRSOiDEUS, Gray, with ovate-oblong to lanceolate leaves, the branches ascending and often short, and the thyrsoid or spicate-glomerate heads less secund. N. Y.

to Ill.--Var. HIRSUTICAuLIS, Gray, the slender stem and the midveins of the long narrow leaves very hirsute. N. Y. and Ky.--Var. BiFRONS, Gray, a luxuriant form with large thin leaves and rather larger heads loosely disposed on the spreading branches. Ky. to Ill.

[+][+][+][+] _Involucre various, the heads when numerous densely or loosely paniculate on erect or ascending branches._

[++] _Cauline leaves sessile, but the base not cordate nor auriculate (except in forms of n. 41), nor winged-petiole-like; glabrous or nearly so._

[=] _Heads small or middle-sized; scales narrow, in several lengths, the erect green tips not dilated._

36. A. Tradescanti, L. Stem much branched (2--4 high); the numerous heads (2--3" high) somewhat panicled or racemed; leaves lanceolate to linear, tapering to a long slender point (2--6' long), the lower somewhat serrate in the middle; involucral scales linear, acutish, partly green down the back. (A. tenuifolius, previous ed.)--Low grounds, Ma.s.s. to Minn., and south to Va. and Ill. Rays short and narrow, white or purplish. Some forms approach n. 32--34, others differ from A.

paniculatus only in the smaller heads and shorter ray.

37. A. paniculatus, Lam. Stem (2--8 high) much branched; the branches and scattered heads (about 4" high) loosely paniculate; leaves long-oblong to narrowly lanceolate, pointed, the lower serrate; scales narrowly linear, with attenuate green tips or the outermost wholly green. (A. simplex, previous ed.)--Shady moist banks; common. Rays white or purplish, 3--4" long. Approaches in its different forms the preceding and the two following. A slender form with linear leaves, in northern bogs, resembles n. 40.

38. A. saliciflius, Ait. Like the last; the leaves commonly shorter, firmer, often scabrous, less serrate or entire; involucre more imbricated, the firmer linear scales with shorter acute or obtusish green tips; heads as large, disposed to be thyrsoid or racemose-cl.u.s.tered; rays rarely white. (A. carneus, previous ed.)--Low grounds, N. Eng. to Minn., and southward; most abundant westward.--Var.