256 



PLANT LIFE. 



cross-pollinatioii, the agency of wiiij or water or insects is 

 employed. To the pecnharities of these \arioiis agents, 

 flowers adapt thenisehes in character of pollen, color, nectar, 

 odor, form of jjarts, time of de\'elopment of slarnens and 

 stigma, etc. For an account of these see *f 477-4S2. 



359. Bracts. — In the immediate neighborhood of the 

 perianth the leaves are usuall)' modi- 

 fied at least in form and size, and 

 not infrequently in color. The 

 lea\es in whose axils the flowers 

 arise arc called bracts, as are also 

 those which subtend branches of the 

 inflorescence (//', h' , h' , flg. 139). 

 The axis of the flower, when 

 elongated beneath it, usually bears 

 one or more bractlels. 



The bract is sometimes large and 

 surrounds the entire inflorescence, 

 as in Indian turnip (fig. 279) and 

 the calla, when it may be \ari- 

 ously colored. Highly colored 

 bracts occur in the scarlet sage 



Fig. 279— InflnrescuncL- .if Indian and, with inCOUSpicuOUS flowers, 

 turnip (a s/'<tili.v). surrounded 



by a large striped and mottled in poiuSCttia and painted CUP, 



bract, the i/),i///f. Natural size. ' '' 



— .After (iray. whilc tlic four large whitish bracts 



of dogwood are the only conspicuous part of the inflores- 

 cence (fig. 280). 



Tracts are aggregated to firm an iin'ulucre beneath a head 

 (Ti 104), as in the sunflower fimily (figs. 2S1, 409), or an 

 um])el (^ 104), as in the |iarsiiip. The perianth may be 

 almost or iiuile wauling, and llie bracts and bractlets may 

 be the oul\' protccti\e lea\es for the sporophylls, as in the 



generally its final result, (he terms close- (ir self-fertilization and cross- 

 ferlilizalioii \vere forinerly used. The woril pollination is jireferalile. 



