246 COMPOSITE FAMILY. 



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

 heads smaller. 



* * 11 Receptacle and disk conrex ; heads viiddle-sized or rather small, 

 the disk variims ; leaves opposite or alternate; Jloiceriny throughout 

 late summer and autumn. 



•*- Disk dark-purple or brown, contrasting loith the yelhnn rays. 



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

 mostly corymbed ; involucre of leaf-like spreading scales. 



H. angustif6Iius, Linn. Slender rough stems 2°-6° high ; lower leaves 

 opposite and rouL;h, revolute. Pine barrens, N. J., S. 



H. orgyalis, DC. Stems (0°-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, hearing solitary 



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



scales. 



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

 oblong, upper ones lance-lincar 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. 



+- 1- Disk yelloin as well as the rays, or hardly dingy-brownish. 



++ Scales of the invducre short and broadly lanceolate, regularly imbri- 

 cated, xcithout leaf like tips; leaves nearly all opposite and nearly 

 entire. 



H. occidentalis, 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. m6llis, Lara. - 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 diiefly alternate and not triple-ribbed. 



H. grdsse-serratus, Martens. Smooth and glaucous, G°-10° ; leaves 

 lonu-laiici'olatc, pi'lioled, serrate. Ohio, W. and S. 



H. gigant^us, Linn. Rough and rather hairy, 3^-10° high, with Jance- 

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

 grounds. 



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

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



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



H. divaric^tus, liinn. 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. hirstitus, liaf. Differs from the preceding in its rough-hairy stem 

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



H. 8trum6sus, Linn. Stems mostly smooth, 3°-4° high ; leaves broadly 

 laneeolati' 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. 



