224 FOUNDATIONS OF BOTANY 
1. S. perfoliata, A. DC. SprecuLarra. Stem erect, simple or 
branched from the base, angles roughened, 10-20 in. high. Leaves 
ovate to lanceolate, acute at the apex, sessile, crenate or entire, the 
upper bract-like. Flowers solitary or in pairs. Corolla blue, often 
wanting. Capsule cylindrical, smaller above. In waste places.* 
100. COMPOSITZ. ComposiTE FAMILY. 
Flowers in a dense head, on a common receptacle, sur- 
rounded by an involucre composed of many bracts (Fig. 22), 
Fie. 22. — Flower-cluster of Bachelor’s Button (Centaurea Cyanus). 
