COMPOSITAE (COMPOSITE FAMILY) 521 
BROWN KNAPWEED 
Centatirea Jacea, L. 
Other English names: Rayed Knapweed, Brown Centaury. 
Introduced. Perennial. Propagates by seed. 
Time ofbloom: June to September. 
Seed-time: Late July to November. 
Range: New England States, southward to New Jersey. 
Habitat: Fields, pastures, and waste places. 
An immigrant from Europe not yet very widely disseminated in 
this country. Stems, several from the same thick, woody, branch- 
ing root, erect, stiff, grooved, slender, one to two feet in height, 
branching near the top. Leaves narrowly lance-shaped, the lower 
ones sparsely toothed and tapering to a petiole, the upper ones 
entire and sessile. Heads showy, an inch or more broad, with 
rosy purple corollas, all tubular but the outer row with enlarged 
and lengthened lobes, simulating rays; these showy florets are 
sterile; involucres nearly globose, the bracts closely imbricated, 
glossy dark brown, the outer row fringed, the middle ones slightly 
lacerate, the inner ones entire or nearly so. Achenes four-sided 
and without pappus. . 
Means of control 
Prevent seeding by cutting while in early bloom, and, if the area 
infested is small and the plants are not too numerous, grub out or 
hand-pull the perennial roots when the ground has been softened 
by rain. Otherwise they may be destroyed by putting the land 
under cultivation. 
BLACK KNAPWEED 
Centatirea nigra, L. 
Other English names: Horse-knobs, Hardheads, Loggerlieads, Hurt- 
sickle, Spanish Buttons, Black Centaury. 
Introduced. Perennial. Propagates by seeds. 
Time of bloom: July to September. 
Seed-time: Late August to November. 
Range: Newfoundland to Ontario, and southward to New Jersey. 
Habitat: Fields, pastures, roadsides, and waste places. 
