600 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 2 



broad, subbipinnate, at first tomentulose, later becoming 

 glabrous or essentially so, divisions narrow, unequal, carti- 

 laginous-apiculate ; inflorescence a terminal corymbose cyme ; 

 heads 10 to 12 mm. high, radiate; involucre cylindric- 

 campanulate, calyculate with short linear subulate bracteoles ; 

 bracts of the involucre 7 to 9 mm. long, brownish- or black- 

 tipped, shorter than the numerous flowers of the disk; ray- 

 flowers about 8 ; achenes canescent-pubescent. 



Distribution : northern Mexico. 



Specimens examined: 



Chihuahua: ledges of the Sierra Madre, alt. 2955 m., 7 Oct., 

 1887, Pringle 1318 (Gray Herb., Kew Herb., and Mo. Bot. 

 G-ard. Herb.), type. 



13. S. durangensis Greenm. Field Col. Mus. Bot. Ser. 



2 : 275. 1907 



Plate 18 



8. ctenophyllus Greenm. Proc. Am. Acad. 43 : 20. 1907, not 

 Phil. 



An herbaceous annual, or becoming perennial by the de- 

 velopment of a ligneous base; stem simple or branched, erect, 

 3 to 4 dm. high, arachnoid-tomentose ; leaves lanceolate, 2 to 

 9 cm. long, 1 to 2.5 cm. wide, more or less pinnately divided, 

 permanently arachnoid-tomentulose on both surfaces, lower 

 leaves petiolate, upper sessile ; inflorescence a terminal tomen- 

 tulose corymbose cyme; heads numerous, 8 to 10 mm. high, 

 radiate, calyculate; involucre campanulate, glabrous or 

 nearly so; bracts of the involucre 13, linear-lanceolate, 5 to 

 6 mm. long, minutely black-tipped, penicillate; ray-flowers 5 

 to 8, ligules pale yellow ; disk-flowers 20 to 30 ; achenes canous- 

 hirtellous. 



Distribution: northern Mexico. 



Specimen examined: 



Durango: barranca, below Sandia Station, alt. 2135 m., 15 

 Oct., 1905, Pringle 10105 (Gray Herb., Field Mus. Herb., and 

 Mo. Bot. Gard. Herb.), type. 



Sect. 3. Jacobaeae DC. 



3. Jacobaeae DC. Prodr. 6 : 348. 1837; Hoffm. in Engl. 

 & Prantl, Nat. Pflanzenf. IV, Abt. 5, 297. 1892; Greenm. 



