230 
IOWA ACADEMY OF SCIENCES. 
Gray. Man. 68. 5 Ed. 
Carduus altissimus, L. Sp. PI. 824. 1753. 
Britton & Brown Illustr. FI. N. St. 8: 485. 
f. 4059. 1898. 
Tall, widely branched, biennial, live 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 — afoot or more long, ovate or oblong, nearly entire orspinulose, 
the upper with a few prominent or 9pinulose teeth orsomewhat pin- 
natilid. 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. Iowensis and 
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. Galva, F. R. S. Aby, S. U. I. Iowa City, T. H. 
Macbride. Johnson County, B. Shimek. 
REFERENCES TO OCCURRENCE IN IOWA. 
Arthur, Contr. FI. la. 1: 20. Bessey, Contr. Ia. FI. 109. 
Nagel & Haupt, Phaen. of Davenport 159. Barnes, Rep- 
pert, and Miller, FI. Scott and Muscatine Counties 234; 
Halsted, Prel. List Ia. Weeds 42; First Blooming of Spring 
