74 



A TEXTBOOK OF BOTANY 



[Cu. Ill, 9 



grows out of its axil : wliile later this Ijract serves as a 

 against wliieh the wind acts in transporting the seeds. 



'sail" 

 Verv 



Fig. 4G. — Various fitrms of conmiou bulbs. Nos. .3, Easter Lily, 



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

 composed mainly of storage leaves. Nos. 2, Coloca.^ia antiqiiorum. and 



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

 and S, Lily of the \^alle>', a rootstock, called a "pip." (From Bailed".; 



striliing are the eases where the Ijracts become highlj' colored, 

 thus forming the showj- 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 sUghtly chfferent 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 clilurophyll. 



Another striking case of 

 tlie combination of a new 

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

 traps in which insects are caught antl digested. Thev all retain 



Fig. 47. —A leaf and 

 the specialized brar't in .American 

 Linden. (From Bailej'.) 



