COMPOSITE. (COMPOSITE FAMILY.) 259 



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. COrdifolius, L. Stem much branched above, the spreading or di- 

 verging 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 oppressed 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 hairv, also 

 with the leaves all narrower. Apparent hybrids with u. 35 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 base, on margined petioles ; the upper lanceolate or linear, 

 pointed at both ends ; scales of the oblong involucre linear, tapering into aid- 

 shaped slender and loose tips. Dry ground, N. Y. and Perm, 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, Liudl. Pale with fine gray pubescence ; leaves 

 cordate to cordate-lanceolate, mostly on margined petioles, the uppermost 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 lowest leaves ovate, moderate! i/ or 

 obscurely cordate, the uppermost sessile and pointed at both ends ; heads larger, 

 rather few in a loose thyrse or panicle, the I i near-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. 



-t- Smooth and glabrous throughout (or nearly so, except forms of u. 30), and usu- 

 ally pale and glaucous ; involucral scales closely imbricated, firm and whitish- 

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



+-* Rays 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, 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., 111., Mo., and southwestward. Well-marked and handsome. 



26. A. laevis, 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 lima r, 

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



