386 COMPOSITAE. 



Along streams in the mountains at low altitudes. Differs from A. amplexi- 

 caulis Nutt. mainly in its narrower leaves. 



Arnica aspera Greene. Sparsely pilose; stems tufted, 40-60 cm. high; 

 leaves ovate-lanceolate, saliently dentate, hairy on both sides, the cauline 

 sessile, 4-6 cm. long; heads mostly 3-5, slender- peduncled; involucres campan- 

 ulate; tegules pustulate-hairy; akenes setose; pappus tawny. 



Along alpine rivulets at 1700 m. altitude, the type specimen from Mount 

 Rainier. 



Arnica mollis Hook. Herbage villous-pubescent, somewhat glandular 

 above; stems 20-^iO cm. high; leaves oblong to oblong-lanceolate, entire or 

 denticulate, mostly acute, the lower ones petioled, 5-10 cm. long; cauline 

 leaves 3-5 pairs, the upper ones remote, sessile; heads mostly 3, rarely 5-9, 

 4-6 cm. broad; tegules glandular, lanceolate, acute; akenes hairy. 



Along alpine rivulets at 1500-2000 m. altitude. 



539. SENECIO.* 



Herbs (in ours) or shrubby plants; leaves all alternate; heads 

 usually solitary or in corymbs, many-flowered ; flowers yellow, all 

 fertile; ray-flowers pistillate or occasionally none; tegules her- 

 baceous, mostly narrow, equal, in one row, or with a few short 

 outer (calyculate) ones; receptacle flat or merely convex, naked; 

 pappus of very numerous and mostly white, fine and soft capillary 

 and merely scabrous bristles; akenes terete or somewhat angled, 

 usually 5-10-ribbed. 



Annuals. 



Heads discoid ; short outer tegules black-tipped. S. vulgaris. 

 Heads with short rays; short outer tegules few, 



not black-tipped. S. syhaticus. 



Biennials or perennials; heads usually radiate. 

 Leaves pinnately divided. 



Stem 30-50 cm. high. S. harfordii. 



Stem 10-20 cm. high. 5. flettii. 



Leaves all undivided or those of the stem pinnately 



lobed. 



Heads discoid (except in subsp. fallax). S. pauciflorus. 



Heads radiate. 



Heads few, terminating the stem and 



branches. 



Foliage glabrous. 5. ductoris. 



Foliage tomentulose. S. websteri. 



Heads usually numerous, in a terminal 



corymbose cyme. 



Stem leafy to the inflorescence. S. triangularis. 



Stem leafy below, naked above. 

 Tegules black-tipped. 



Herbage arachnoid tomentulose. S. lugens. 

 Herbage pubescent with coarse 

 jointed hairs or glabrous. 

 Herbage glaucous, glabrous, 

 fleshy; leaves mostly en- 

 tire. S. hydrophilus. 



*The account of this genus has been prepared with the assistance of Dr. J. 

 M. Greenman. 



