composit.t:. (composite family.) 259 



f)ase, or directly sessile by a heart-shaped base ; involucre obovoid, the scales 



less rigid. — Dry copses; commou. 



*-f -t-f- Leaves conspicuous/ 1/ serrate ; heads small ; rays pah. blue or nearlij ichite. 



21. A. COrdifolius, L. Stem much branched above, ?/ie s/)rertr//»^ o/* r//- 

 ver(jin(i branches bearing veri/ numerous panicled heads; lower leaves all heart- 

 shaped, on slender and mostly naked ciliate petioles; scales of the inverseh/ 

 conical involucre all appressed and tipped icith verij short green points, obtuse or 

 acutish. — Woodlands ; very common. — Heads profuse, but quite small. Vaiies 

 with the stem and leaves either smooth, rougliish, or sometimes hairy, also 

 with the leaves all narrower. Apparent hybrids with n. 3.5 also occur. 



22. A. sagittifolius, Willd. Stem rigid, erect, with ascending branches 

 bearing numerous racemose heads; leaves ovate-lanceolate, pointed; the lower 

 heart-shaped at l)ase, 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, X. Y. and Penn. to Ky., and north- 

 ward. — 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 pubescence; leaves 

 cordate to cordate-lanceolate, mostlij on margined petioles, the upjjermost lan- 

 ceolate and sessile; scales acute or acutish. — Passing into the last. Open 

 ground, etc., 111. to Minn, and Kan. 



24. A. Lindleyanus, Torr. & Gray. Rather stout, 1 -2° high, sparsely 

 pubescent or nearly glabrous; radical and loa-est leaves ovate, moderateli/ or 

 obscurelg 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 silkg-canescent. 



•- Smooth and glabrous throughout (or nearlij so, except forms of n. SO), and usu- 

 ally pcde and glaucous ; involucral scales closelg imbricated, firm and whitish- 

 coriaceous below, green-tipped ; leaves firm, usually entire. 



++ iRays violet or blue ; scales rather abruptly green-tipped ; leaves on the branch- 

 lets reduced to rigid subulate bracts. 



25. A. turbinellus, Lindl. Stem slender, 3° high, paniculately branched; 

 leaves oblong to narrowly lanceolate, tapering to each end, witli 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., 111., Mo., and south west ward. — Well-marked and handsome. 



26. A. Isevis, 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 

 hemisphericcd /nro///cre 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, \\kQ those of the last; leaves lanceolate or linear 

 the lower usually long and narrow. — S. W. Va., and southward. 



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