IOWA ACADEMY OF SCIENCES. 233 



This species is common in Nebraska and Colorado, but 

 in western Nebraska, Kansas and Colorado the species has 

 a tendency to vary into the var. inegacepltdlus. 



Distribution. — Kossuth County, Pammel, 607 I. S. C. 

 Also reported from Muscatine County. 



REFERENCE TO OCCURRENCE IN IOWA. 



Barnes, Miller, and Keppert, Fl. Scott and Muscatine 

 Counties. 234. 



CNICUS UNDULATUS,VAR. MEGACEPHALUS, A. Gray. 



C. undiilatus var. meqacephalus. A. Gray. Proc. Am. 



Acad. 10: 42. 1874. 



. Syn. Fl. N. Am. 1 : 403. 1884. 



Carduus undidattis megacepJialus. (A. Gray.) Porter 



Mem. Tor. Bot. Club 5: 345. 1894. 



Britton «fe Brown, Illustr. Fl. N. St. 3: 486. 



1898. 



Branches bearing single large heads with purple flowers two 

 to two and one-half inches high, involucre more or less strongly 

 appressed, scales with a prominent glutinous ridge, achenium four 

 lines long, striate. 



Distribution, Iowa. — Boone, introduced, G. W. Garver. 



CNICUS CANESCENS, Pammel n. c. 

 Cnicus undulatus var. canescens. Gray. Proc. Am. Acad. 



10:42. 1874. 

 . Gray. Syn. Fl. N. Am. 1 : 403. 1884. 



Cirsium canescens. Nutt. Trans. Am. Phil. Soc. 7: 420. 

 . Torrey & Gray. Fl. N. Am. 2: 461. 1843. 



Branching perennial two to four feet high, woolly throughout, 

 branches bearing single medium-sized ht^ads. stem angled, white 

 woolly; leaves, radical eight inches to a foot long, the divisions 

 usually two-lobed, prominently ribbed, ending in f-tout spines; stem 

 leaves, except the lower, one to four inches long, pinnatifid, the 

 upper sessile, slightly undulate with numerous sharp bristles, the 

 upper surface slightly roughened, and a slight cottony down, the 

 lower white woolly; heads one one-half to two inches high, bracts 

 of the involucre somewhat arachnoid, lower scales with a broad 

 base, glutinous ridge, and ending in a minutely serrated spine, 

 inner scales long attenuated, tips straw-colored; flowers purple. 



