246 COMPOSITE FAMILY. 



H. argophyllus, Torr. & Gray. Texas, cult, for its hoary-white foliage ; 

 heads smaller. 



* * 2/ Receptacle and disk convex ; heads middle-sized or rather small, 

 the disk various; leaves opposite or alternate; flowering throughout 

 late summer and autumn. 



*- Disk dark-purple or brown, contrasting with the yellow rays. 



++ Leaves long and linear, l-nerved, entire, sessile; heads small and 

 mostly corymbed; involucre of leaf-like spreading scales. 



H. angustifdlius. Linn. Slender rough stems 2-6 high ; lower leaves 

 opposite and rough, revolute. Pine barrens, N. J., S. 



H. orgyalis, DC. Stems (6-10 high); leaves crowded, very narrow, 

 alternate, smooth ; flowers late. W. of the Miss. Cult, for its tall strict 

 habit. 



- <-* Leaves oval or lanceolate, opposite ; stems l-3 high, bearing solitary 



or few long-peduncled, rather large heads; involucre of short, close 



scales. 



H. heterophyllus, Nutt. Rather hairy, with lowest leaves oval or 

 oblong, upper ones lance-linear and few ; scales of involucre lanceolate. 

 Low pine barrens, Ga., S. 



H. rigidus, Desf. Dry prairies W. and S.; rough, with thick firm 

 leaves lance-oblong or the lower oval ; scales of the involucre ovate or 

 oblong, blunt. 



<- *- Disk yellow as well as the rays, or hardly dingy-brownish. 



w- Scales of the involucre short and broadly lanceolate, regularly imbri- 

 cated, without leaf-like tips; leaves nearly all opposite and nearly 

 entire. 



H. occidentals, Riddell. Somewhat hairy, with slender simple stems 

 l-3 high, sending off runners from base, naked above, bearing 1-5 

 heads ; lowest leaves ovate or lance-ovate ; upper ones narrow, small and 

 distant. Ohio, W. and S. 



H. mdllis, Lam. Soft white-woolly all over, 2-4 high, leafy to the 

 top, the leaves heart-ovate and partly clasping. Ohio, W. and S. 



" ++ Scales of the involucre looser and leafy-tipped ; stems leafy to the 

 top. 



= Leaves chiefly alternate and not triple-ribbed. 



H. gr6sse-serratus, Martens. Smooth and glaucous, 6-10 ; leaves 

 long-lanceolate, petioled, serrate. Ohio, W. and S. 



H. gigant&us, Linn. Rough and rather hairy, 3-10 high, with lance- 

 olate serrate, nearly sessile leaves, and pale-yellow rays. Common in low 

 grounds. 



= = Leaves mainly opposite, except in the last, 3-ribbed at base or triple- 

 ribbed. (Several species, the 'following the most important.) 



|| Sessile or short-petiolate, entire, or serrulate. 



H. divaricatus, Linn. Common in dry sterile soil ; stem smooth, 

 l-3 high ; leaves rough ovate -lanceolate, tapering to a point, and 

 3-nerved at the rounded sessile base. 



H. hirsutus, Raf. Differs from the preceding in its rough-hairy stem 

 l-2 high, and leaves with narrower base more or less petioled. Ohio, W. 



H. strum6sus, Linn. Stems mostly smooth, 3-4 high ; leaves broadly 

 lanceolate or lance-ovate, rough above and whitish or white-downy be- 

 neath, their margins beset with fine appressed teeth, and petioles short 

 and margined. Common. 



