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, salicntly dentate, hair>' on both sides, the cauline 

 sessile, 4-6 cm. long; heads mostly 3-5, slender-pedunclcd; 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-^0 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 hair^-. 



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. 5. vulgaris. 

 Heads with short rays; short outer tegules few, 



not black-tipped. 5. sylvaticus. 



Biennials or perennials; heads usually radiate. 

 Leaves pinnately divided. 



Stem 30-50 cm. high. 5. harfordii. 



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



Leaves all undivided or those of the stem pinnately 

 lobed. 

 Heads discoid (except in subsp. /a//ax) . 5. pauciflorus. 



Heads radiate. 



Heads few, terminating the stem and 

 branches. 

 Foliage glabrous. S. dudoris. 



Foliage tomentulose. 5. websteri. 



Heads usually numerous, in a terminal 

 corymbose cyme. 

 Stem leafy to the inflorescence. S. triangidaris. 



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. 



