426 Karl M. Wiegand and Arthur J. Eames 



36. Centaurea L. 



a. Leaves not pinnatifid, rarely lobed. 



b. Involucral bracts with abruptly much-dilated tips ; marginal flowers moderately 

 enlarged. 

 c. Body of dilated tip of bract orbicular, lacerate, covering the scales under- 

 neath, brown or yellowish. 1. C. Jacea 

 c. Body of dilated tip of bract oval, triangular, or ovate-lanceolate, pectinate. 

 d. Heads globular ; cilia longer than the width of the body of the dilated 

 tip; tips large, completely covering the scales beneath, la. C. Jacea, 



var. nigra 

 d. Heads ovoid; cilia about equaling the width of the body of the dilated 

 tip; tips not completely covering the scales beneath. lb. C. Jacea, 



var. pratensis 

 b. Involucral bracts lanceolate, without dilated tips ; marginal flowers especially 

 large and showy. [C. Cyantts] 



a Leaves pinnatifid, with narrow divisions ; involucral bracts without dilated tips 

 but with the apex pectinate. 2. C. maculosa 



1. C. Jacea L. 



A weed in dry sandv or gravelly fields ; rare. Aus.-Sept. 



Hill s. w. of West Danbv, 1922 (IV. C. Muenscher & W. E. Manning) ; Bull 

 Hill. Xewfield, 1919; two miles n. of Connecticut Hill, 1923 (J- P. Young) ; near Mud 

 Pond, McLean Bogs, 1923 (/. A. Turner) ; n. e. of Pout Pond, 1916-1919 (A". M. W. 

 & P. P. Metcalf) ; apparently well established at each place. 



Naturalized from Eu. in various parts of X. A. 



la. C. Jacea L., var. nigra (L.) Briq. Knapweed. Spanish Buttons. 



A weed by roadsides and in fields, in gravelly soils (a calcifuge, Briquet) ; rare, 

 but becoming more frequent. July-Aug. 



Enfield Township (/. P. Young) ; C. U. campus, near McGraw Hall, 1875 (D.) ; 

 pasture near McLean Bogs; field, e. branch of Salmon Creek, Genua {A. H. Wright), 



Naturalized from Eu. in various parts of X. A. 



lb. C. Jacea L., var. pratensis (Thuill.) Vis. 



A weed in dry gravelly or stony soils ; rare. Aug. 



Hilltop. Xorth Spencer (A. J. E. & L. H. MacDaniels) ; White Church (L. F. 

 Randolph ) . 



Introduced from Eu. in various parts of X. A. 



Briquet (Monog. de Cent. d. Alps Marit., 1902) is apparently correct in reducing 

 these two forms, la and lb, to varieties of C. Jacea. 



[C. Cyanus L. Bachelor's Button. Corn-flower. 



An occasional escape from gardens to waste places. 



C. L". campus (D. !) ; '"E. State Street, Ithaca, and elsewhere, appearing almost 

 every year" (D.) ; "in 1885, in a wheat field east of Case Woods, mam specimens " 

 (£>.)■ Doubtfully established.] 



2. C. maculosa Lam. 



A weed in dry gravelly or sandy fields; rare, but becoming more frequent. Aug- 

 Sept. 



Hilltop, X'orth Spencer ; pastures one-half mile n. of Summit Marsh, abundant ; e. of 

 Dryden village, 1912 (Miss L. J. Szveetland) ; s. of Mud Pond, McLean Bogs; e. 

 of Pout Pond. First reported in 1912. 



Mass. to N. J. and Pa. Xaturalized from Eu. 



