256 THE COMPOSITE FAMILY. [ Centaurea. 
Leaves mostly entire or toothed. Appendages almost con- 
cealing the bracts themselves . . 1. C. nigra. 
Leaves deeply pinnatifid. Involucral bracts showing their . 
green centres with a black fringed border 2. C. Scabiosa, 
Involucral bracts ending in, or bordered by, minute teeth or 
prickles. 
Outer florets bright blue. An erect cornfield annual . » 8. 0. Cyanus. 
Florets purple. A spreading Jersey perennial . » . 4, C, aspera. 
Involucral bracts ooene in a long, stout prickle, 
Florets purple . j . : : . ° . 5. C. Caleitrapa. 
Florets yellow . : ‘ : - : - : Z ! . 6. C, solstitialis. 
C. montana, from central and southern Europe, and a few others, are 
occasionally cultivated in our gardens, and two species from the Mediter- 
ranean, C. salmantica and C. paniculata, have been found in the Channel 
Islands, but do not appear to be established there. 
1. C.nigra, Linn. (fig. 570). Black Centaurea, Knapweed or Hard- 
heads.—A perennial, with erect stems, hard and branched, 1 to 2 feet high. 
Leaves from linear to lanceolate or oblong ; the upper ones entire or nearly 
so, clasping the stem at their base; the lower with a few coarse teeth or 
short lobes; all green, and rather rough with a few minute hairs, or 
slightly cottony underneath when young. Involucres globular, on terminal 
peduncles; the bracts closely imbricate, so as only to show their appendages, 
which are brown or black, and deeply fringed, except on the innermost 
bracts, where they are shining and usually jagged. Florets purple, either 
all equal or the outer row much larger and neuter as in the rest of the genus. . 
Achenes slightly hairy, often apparently without any pappus, but really 
crowned by a ring of very minute, scaly bristles, occasionally intermixed 
with a few longer, very deciduous ones. 
In meadows and pastures, throughout Europe and western Asia, except 
the extreme north, extending probably all across Russian Asia, Very 
abundant in Britain. Fil. all summer. The two forms, with or without 
the outer row of large florets, are so different in appearance that it has 
often been attempted to distinguish them as species, but it has been now 
proved that they are mere varieties, and it is even believed by some that 
the same plant will appear in some years with and in others without the 
ray. C. decipiens, Thuill., (C. nigrescens, Bab.) is a variety, occurring in 
Sussex, more frequently in some parts of the Continent, with the appen- 
dages of the involucraliscales of a much paler colour, with a much shorter 
fringe, or only jagged. This form passes, however, gradually into the 
common one. 
2, C. Scabiosa, Linn. (fig. 571). Greater Centaurea.—A stouter 
plant than C. nigra, more branched at the base; the leaves deeply pin- — 
natifid, with linear or lanceolate lobes, often coarsely toothed or lobed. 
Flower-heads large, with purple florets, the outer ones always enlarged and 
neuter. Involucral bracts broad, bordered only with a black appressed 
fringe, leaving the green centre exposed. Pappus of stiff hairs or bristles 
nearly as long as the achene. i 
In pastures, waste places, roadsides, etc., throughout Europe and Rus- : 
sian Asia, except the extreme north. Rather frequent in England, less so — 
in Scotland, and scarcely indigenous beyond south-eastern Perth and 
Forfar, ieee and rare in Ireland. FU. summer and autumn. 
3, C.Cyanus, Linn. (fig. 572). Corn Centaurea, Bluebottle or Corn 
