THE INFLORESCENCE. 115 



tion as they approach the upper part of the floral axis. Hence 

 the leaf gradually passes into the bract in consequence of its 

 development in the neighborhood of the flower, and the same 

 proximity doubtless produces the abortive leaves of the calyx. 



Sometimes, however, the bracts are as richly colored as the 

 petals themselves, as in Castilleja euchroma, or the painted 

 cup, which owes all its beauty to its conspicuous and deep 

 scarlet bracts. The curious envelope of the Indian turnip, 

 (Arum triphyllum), and the Ethiopian lily, (Calla Ethiopica), 

 called a spathe, is nothing but a colored bract ; so also the 

 conspicuous petal-like involucre or bract of the dogwood, 

 (Cornus florida), is much more showy than the real flowers 

 which it surrounds. 



Bracts are generally distinct from each other ; but when the 

 flowers are brought together and situated on a common recep- 

 tacle as in Umbelliferous and Composite plants, the bracts are 

 also brought together and surround the basis of the general 

 receptacle in one or more verticils or whorls. In the Umbelli- 

 ferse, there is usually a whorl of bracts surrounding the general 

 umbel, which is called an involucre, and in some genera another 

 whorl of bracts also surrounds the umbellets, termed an 

 involucel. In the Compositse, the involucre consists of several 

 rows of imbricated bracts which surround the head of flowers, 

 as in the Aster, the Solidago and the Helianthemum. Not 

 unfrequently the separate flowers also are subtended by bracts, 

 termed palese or- chaff. In the grasses, bracts occupy the place 

 of both calyx and corolla. They form the cupula or cup of 

 the acorn, and also the husky covering of the hazel-nut. 



The leaf appears to pass by means of the bract into the 

 sepal or calyx leaf. There is in reality no exact limits between 

 common leaves and bracts, and the limits between bracts and 



