69 
591. C. undulatus, Gray. Thistle. 
Pine Station, north to Colehour, Ind. ; rare. 
Plants usually not very canescent, only whitish ; 1 to 2 feet high ; 
heads generally single; not very common, Pine Station, Ind., 
Hill. (B. P.) 
This form does not have the true characteristics of C. undulatus, 
and may possibly be a variety of C. pumilus. We place it here 
provisionally.* 5 * 
'4”fi92. C. altissimus, Willd. Tall Thistle. 
Fields and newly-cleared lands and in open woods ; frequent. August. 
pi ^ 
598. c. altissimus, Willd., var. discolor, Gray. 
C. discolor , Spreng. 
With the typo, especially southeast; frequent. July — August. 
+ 594. C. muticus, Ph. Swamp Thistle. 
Swamps, wet fields and banks; frequent, especially southward. 
July 15th — September. . ' 
In drier soil it seldom attains a height of more than two feet. 
-^595. C. arvensis, Hoffm. Canada Thistle. 
Prairies and waste places; common or abundant. July — September. 
Along some of the streets in the outskirts of Chicago, it attains a 
height of 8 to 4 feet; on the open prairies, it is usually not over 6 
inches. Much branched. Flowers often very pale rose-color, and 
a specimen near Garfield Park bore nearly white heads. 
CENTAUREA, L. 
596. C. cyanus, L. Bluebottle. Bachelor’s Button. 
Escaped from cultivation at Evanston and Barrington, and is 
seemingly well established. July. (B. P.) 
KRIGIA, Schreb. 
597. K. virginica, Willd. Krigia. Dwarf Dandelion. 
Sandy soil; rare. April — July. 
Colehour, Ind., 1884-86. Miller's, Ind., July, Bastin , Hill. Lake, 
Ind., Babcock. 
4 - 598. K. amplexicaulis, Nutt. Cynthia. 
Cynthia virginica, Don. 
Rich and moist fields and banks; frequent. June. 
*Since the above was written, specimens have been sent to Mr. Canby, who 
considers it anew species, naming it C. hillii, in honor of Prof. E. J. Hill, who 
first made a critical study of the form. See Appendix I. 
