42 PROCEEDINGS OP THE AMERICAN ACADEMY 



++ ++ Orgyales et ultra; capitulis mediocribus ; spinulis involucri aris- 

 tiformibus debilibus. 



C. ALTissiMUS Wilkl. Carduus altissimus Linn. Cirsium diver- 

 si folium DC. Folia caulina subintegra vel subjDinnatifida. — Penn- 

 sylvania and Wisconsin to Louisiana. 



C. DISCOLOR Muhl. in Willd. Folia profunde pinnatifida segmentis 

 angustis. — Canada to Illinois and southward along the upper country. 



-)— -i— Suhconcolores horeales ; foliis fere pinnatisectis, segmentis line- 

 aribus elongatis. 



C. PiTCHERl Torr. in Eaton, Man. Bot. Cirsium Pitcheri Torr. «& 

 Gray. G. Hooherianum var. Gray in Stevens, Rep. Pac. R. R. 12, 

 J). 45. — Sandy shore of Lake Superior and (recently) of Lake Michi- 

 gan. Also Montana Territory, Dr. Suckley. 



■I— H— -t— Suhconcolores occidentales ; foliis subintegris vel pinnatifidis, 

 junioribus saltern pagina superiore arachuoideo-dealbatis, maturis 

 quandoque glabratis. 



++ Antherarura appendices cuspidato-acuminatae : caulis pedalis, raro 

 2-3-pedalis. 



C. UNDULATus. Carduus (Cmcus) undulatus Nutt. Gen. C. dis- 

 color Hook. Fl. Bor.-Am. pro parte. Cirsium undidatum Spreng. ; 

 Torr. & Gray, Fl. C. Dourjlasii DC. Prodr. 6, p. 643 ; Nutt. 1. c. 

 C. Hookerianum, Hook. Lond. Jour. Bot. 6, p. 253, non Nutt. — An 

 exceedingly variable species, widely diffused from the Upper Missis- 

 sippi ai>d Saskatchawan region to the Pacific in Oregon, and south to 

 Texas and New Mexico, usually with reddish-purple or occasionally 

 pale flesh-colored or white flowei-s, differing much in the size of the 

 heads, also in the foliage and in the prickles of the involucre. 



Var. CANESCENS {Cirsium canescens Nutt. in Trans. Amer. Phil. 

 Soc. 1. c. & C. undulatum ^. Torr. & Gray) — capitulis vix ultrapolli- 

 caribus — is the more depauperate form of the northern and western 

 plains. Cirsium brevifulium Nutt. 1. c. is the form with less pinnatifid 

 or almost entire leaves. 



Var. MEGACEPHALUS : capitulis 2-2^-pollicaribus ; involucri squamis 

 latioribus dorso planis spinula brevi vel brevissima cuspidatis. — This 

 large-headed form prevails in Texas, &c., but we have it from Minne- 

 sota (Geyer), and from the waters of the Columbia River (Spalding, 

 Lyall) ; and between these two forms most of the specimens are inter- 

 mediate. They also pass into the 



