OF ARTS AND SCIENCES. 39 



II. 



CONTRIBUTIONS TO THE BOTANY OF NORTH 



AMERICA. 



{Continued from Vol. IX., ji- 218.) 

 By Asa Gray. 



Presented, May 12 aud Oct. 13, 1874. 



I. A Synopsis of the North American Thistles. 



CNICUS Linn., Schreber, Benth. & Hook. 

 (CiRSiuM Toiirn., DC.) 



1. Species IiiquilincB. 



C. LANCEOLATUS Iloffm. Folia decurrentia, superne setoso-aspera. 

 C. ARVENSis Hoffm. Capitula subdioica, parva. 



2. Species Indigence. 



§ 1. Involucrum gradatim imbricatum ; squamis adpressis, exterioribus 

 sensim brevioribus, omnibus nee herbaceo- nee scarioso-appendie- 

 ulatis, intimis in paucis appendice parva seariosa superatis. 



* Folia viridia seu araneoso-lanata (nunquam tomento denso albo- 

 lanufinosa) : caules stepius abbreviati vel simplices : involucri 

 squamoe laxiusculas, plante, subchartacea3, exteriores mucrone vel 

 spinula nee valido nee patente superataj : antherarum appendices 

 acuminata} vel cuspidatte. 

 -J— Atlantic! ; eapitulis mediocribus angustioribus ; peduneulis nudis. 



C. iiEPAXDUS Ell. Cirsium repandum Miehx. Humilis, involuero 

 campanulato. 



C. Lecoxtei. Cirsium Lecontei Torr. «& Gray, Fl. 2, p. 459. 

 Elatior, involuero oblongo vel cylindraceo. 



H— +- Atlantic! ; eapitulis majoribus latis bracteis spinosis nunc sti- 

 patis. 



