74 



A TEXTBOOK OF BOTANY [Ch. Ill, 9 



grows out of its axil ; while later this bract serves as a "sail" 

 against which the wind acts in transporting the seeds. Very 



Fig. 46. — Various forms of common "bulbs." Nos. 3, Easter Lily, 



4, Jonquil, 6, Lilium pardalinum, and 7, Hyacinth, are true bulbs, i.e. are 

 composed mainly of storage leaves. Nos. 2, Colocasia antiquorum, and 



5, Gladiolus, are corms, i.e. storage stems. No. 1, Tuberose, is a tuber, 

 and 8, Lily of the Valley, a rootstock, called a "pip." (From Bailey.) 



striking are the cases where the bracts become highly colored, 

 thus forming the showy part of a "flower/' as in Poinsettia, 



the real flowers of which 

 are small and inconspicu- 

 ous. The sepals and petals 

 of ordinary flowers are also 

 morphologically leaves, as, 

 in a slightly different way, 

 are the stamens and pistils. 

 Colored bracts and petals 

 retain mostly the structure 

 of foliage leaves, excepting 

 that the chlorenchyma now 

 holds other pigments in 

 place of the chlorophyll. 



Another striking case of 

 the combination of a new 

 function with the old is found in the pitchers and other leaf 

 traps in which insects are caught and digested. They all retain 



Fig. 47. — A leaf and 

 the specialized bract in American 

 Linden. (From Bailey.) 



