274 COMPOSITAE. 



1-2 in the upper axils, 1.5-2.5 cm. broad; involucre hemispherical, 1-2 cm. 

 high; bracts green, coriaceous, oblong-lanceolate or ovate, cuspidate, the lower- 

 most leaf-like, entire or nearly so, pubescent; rays usually present, small, 

 scarcely or not exceeding the pappus, sterile; akenes smooth, glabrous, flat, 

 4-nerved; pappus coarse, brownish, nearly as long as the corolla. Kamiack 

 Butte, in open pine woods; very variable. 



Hoorebekia racemosa (Nutt.) Piper. Perennial; stems erect, 60-90 cm. 

 high, sparsely soft- hairy; leaves lanceolate, coriaceous, acute, entire, 5-15 

 cm. long, the cauline sessile, the basal petioled, all somewhat scabrous on 

 both surfaces and with sparse pubescence; heads racemosely or somewhat 

 paniculately arranged, mostly long-peduncled; involucre turbinate or cam- 

 panulate, 1-1.5 cm. broad, the well-imbricated bracts linear, acute, pubescent, 

 rigid and coriaceous, green-tipped; rays 6-8 mm. long; akenes pubescent; 

 style-branches filiform; pappus brownish Dry soil, rather common. 



408. SENECIO. 



Herbs or shrubby plants; leaves all alternate; heads usually 

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

 ray-flowers pistillate or occasionally none; involucral bracts her- 

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

 outer bracts ; 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. 



Annual; calyculate bracts of the involucre closely appressed, 



black-tipped. 5. vulgaris. 



Perennial; calyculate bracts of the involucre not closely ap- 

 pressed, not black-tipped (except in S. atriapiculatus). 

 Leaves or some of them pinnate or pinnatifid, densely 



white-woolly. S. howellii. 



Leaves not pinnate or pinnatifid, not densely white- 

 woolly. 

 Stems clustered, leafy to the inflorescence. 



Leaves triangular-lanceolate, petioled, coarsely 



dentate. S. triangularis. 



Leaves lanceolate, sessile, serrate to subentire. 5. serra. 

 Stems usually solitary; leaves mostly basal, the 



cauline greatly reduced. 



Herbage wholly glabrous, glaucous. S. hydrophilus. 



Herbage usually pubescent, not glaucous. 



Heads 8-10 mm. high; bracts about 13. S. exaltatus. 



Heads 10-12 mm. high; bracts about 21. 



Inflorescence open. S. atriapiculatus. 



Inflorescence dense. S. condensatus. 



Senecio vulgaris L. Annual, sparsely pubescent or glabrous, usually 

 branched, 15-30 cm. high; leaves spatulate or oblong in outline, 1-3 cm. long, 

 half-clasping at base, pinnately-lobed, the lobes short and usually toothed; 

 heads few to many, in corymbs; involucre 5-7 mm. high, the inner bracts 

 linear, acute, often black-tipped, the outer few and short; rays wanting; 

 akenes puberulent; pappus copious, white. Introduced and becoming common. 



Senecio howellii Greene. Perennial, the whole herbage covered with a 

 close white tomentum; stems erect, tufted, 20-40 cm. high; basal and lower 



