Compostte—Centaurca. 265 
the countries bordering the Mediterranean Sea. C. nigra, 
Knapweed or Buttonweed, is a familiar native example. The 
name is of classical origin. We must limit ourselves to a small 
selection. 
Annual Species. 
1. C. Cyanus. Cornflower.—This handsome species is com- 
monly seen in our corn-fields, where its bright blue flower- 
heads are highly attractive. It grows from 2 to 3 feet high, 
bearing numerous terminal stalked flower-heads. Leaves 
linear, entire or lobed, cottony. Under cultivation this species 
has produced white, pink, and purple varieties. 
2. C. Americana (fig. 149).—A very ornamental species, 
Fig. 14y. Centaurea Americana. Fig. 150. Ceutaurea Babylonica. (gp nat. size.) 
(} nat. size.) 
about 3 or 4 feet high. Flower-heads very large, lilac-purple. 
A native of the southern United States. 
