230 IOWA ACADEMY OF SCIENCES. 



Gray. Man. 68. 5 Ed. 



Carduus altissimus, L. Sp. PL 824. 1753. 



— Britton & Brown Illustr. Fl. N. St. 3: 485. 



/: 4059. 1898. 



Tall, widely branched, biennial, five to ten feet high, stems hairy 

 when young, becoming smoothish or with a few scattered bristles 

 when old, rather small heads terminating the branchlets; leave«^, radi- 

 cal — a foot or more long, ovate or oblong, nearly entire or spinulose, 

 the upper with a few prominent or spinulose teeth or somewhat pin- 

 natitid. upper surface slightly rough, and lower woolly; arachnoid 

 heads one and one-fourth to one and one-half inches high; bracts of 

 the involucre arachnoid when young, the outer with a broad base 

 and a black gland running down the back, tipped with a weak 

 spreading bristle, inner bracts much longer than the outer, termina- 

 ting in a colorless recurved triangular tip with a serrated margin, 

 tube of the corolla eight to nine lines long, filaments pubescent, 

 anther tips acute, anchenium smooth, two and one-fourth lines 

 long, bristles of pappus all plumose. 



This species is at once distinguished from C. Ioivent;is Sind 

 C. discolor by its much smaller heads, less deeply pinnatifid 

 leaves, and the smaller number of. branches. It is the 

 tallest of all our thistles, and always grows in forests or 

 on the border of woods. It extends to the Mississippi and 

 some of the immediate tributaries. It rarely occurs in the 

 interior of the state. Common in the eastern states, 

 extending southwest to Missouri and Arkansas, in the tim- 

 bered regions of the Mississippi Valley. 



Distribution. — Clinton, Lyons, No. 66, L. H. Pammel. 

 Dubuque, Iowa, L. H. Pammel. Jasper County, H. W. 

 Norris. 



The following specimens examined by me are typical: 



Iowa — Johnson County, Decatur County, T. J. & M. F, L. 

 Fitzpatrick. Muscatine County, Ferd. Reppert. Ames, 

 Hitchcock. Clalva, F. R. S. khy] S. U. I. Iowa City, T. H. 

 Macbride. Johnson County, B. Shimek. 



REFERENCES TO OCCURRENCE IN IOWA. 



Arthur, Contr. Fl. Ta. 1: 20. Bessey, Contr. la. Fl. 109. 

 Nagel & Haupt, Phaeu. of Davenport 159. Barnes, Rep- 

 pert, and Miller, Fl. Scott and Muscatine Counties 234; 

 Halsted, Prel. List la. Weeds 4*J; First Blooming of Spring 



