COMPOSITE FAMILY. 239 



A. multifldruB, Ait. Pale- or hoary-pubescent, l°-2°, bushy-branched ; 

 leaves rigid and crowded, with rough margins ; rays white (rarely bluish). 

 Common in dry ground. 



— Scales generally oppressed. 



<—> Plant very smooth, pale and glaucescent. 



A. turbinellus, Lindl. Slender, 3°, paniculately branching ; leaves 

 oblong or narrow-lanceolate, with roughish margins ; scales linear, with 

 blunt and short green tips ; flowers violet. HI., S. W. 



A. virgatus, Ell. Strict and simple, with the branches terminated by 

 single heads ; leaves lanceolate or linear, the lower ones long ; scales 

 acutish ; flowers violet. Va., S. 



>—• i-j Plant variously scabrous or hirsute, not glaucescent (except forms of 



the first). 



«-^ Leaves firm in texture, often thickish; heads rather large and showy, 

 the scales with loosish green tips. 



A. N&vi-Belgii, Linn. Short, 6'-2J°, some forms wholly smooth, 

 others with sparse pubescence ; leaves from oblong to linear-lanceolate, 

 usually entire, the upper somewhat auriculate-clasping, the salt-marsh 

 forms nearly fleshy; flowers blue or violet. Very, common, in many 

 forms, along the Atlantic coast, but reaching 111. Elowers late. 



^ ^ Leaves of ordinary texture ; heads mostly smaller, with less prom* 

 inently green-tipped scales. 



^ Heads scattered, borne on the ends of slender bracteate branchlets. 



A. dum6aus, Linn. Smooth or nearly so, l°-3°, loosely branched ; 

 leaves linear or somewhat broader towards the top of the plant, crowded 

 and entire, rough-margined ; involucre bell-shaped, with abruptly green- 

 tipped scales ; rays violet or blue. Common. 



-^ ^v Heads in lax or racemose 1-sided sprays. 



A. racem&sus, Ell. Scabrous-pubescent on the erect or ascending 

 slender branches ; leaves linear and rigid, small, acute, entire ; flowers 

 small, purplish, the scales very narrow and acute. S. C, S. 



A. vimineus, Lam. Glabrous or very nearly so, 2°-5°, very bushy ; 

 leaves small and stiffish, linear or narrow-lanceolate and rather long, the 

 larger ones sparsely serrate ; scales narrow-linear, mostly acute ; heads 

 very numerous, white. Very common. 



A. diffusus, Ait. Pubescent, branchy ; leaves large, thin and lax, 

 lanceolate or broader, sharply serrate ; scales linear, obtuse or acutish ; 

 flowers white or violet. Very common and variable. 



^-s /-v ^-v Heads (in mature plants) paniculate or thyrsoid. 



C Scales subulately green-tipped; rays commonly pure white. 



A. ericoldea, Linn. Smooth or sparsely hairy, l°-3° ; heads often 

 tending rather to be racemose than paniculate, and borne on the ends of 

 erect, much-bracted branchlets ; leaves linear-lanceolate (or the lowest 

 oblong-spatulate), becoming awl-like and stiffish above. Dry grounds. 

 Variable. 



A. polyphyllus, Willd. Tall, 4°-5°, with twiggy branches ; leaves 

 4' or 5' long, linear-lanceolate ; flowers rather large, early. ~K., and S. 



OO Scales not awl-tipped; rays violet to white. 



() Scales of several lengths. 



A. Tradescanti, Linn. Much branched, 2°-4°, the heads small and 

 numerous ; leaves lanceolate to linear, tapering to a slender point, the 



