THE FLOWER SHOOT 143 



concerned in the process of pollination and fertilization, which 

 are necessary (except in very rare cases) for the development of 

 the seed, are formed in the flower or have a very intimate nutri- 

 tive dependence on some of its parts. Many flowers have cer- 

 tain conspicuous, often beautifully colored parts, which, it is 

 believed, attract insects that aid in pollination. 



221. The parts of the flower. There are two sets of organs 

 or members in the complete flower: (i) The floral envelope; 

 (2) the essential members or organs. Examples of complete 

 flowers are the buttercup, spring beauty, bloodroot, apple, rose, 

 pea, fuchsia, etc. The end of the stem to which the parts of the 

 flower are attached is the receptacle. 



222. The floral envelope when complete consists of, i. an 

 outer envelope, the calyx, made up of several leaf -like structures 

 (sepals) , very often possessing chlorophyll, which envelop all the 

 other parts of the flower in the bud; 2. an inner envelope, the 

 corolla, also made up of leaf -like parts (petals), usually bright- 

 colored and larger than the sepals. 



223. The essential members or organs of the flower. 

 These members are also in two sets or kinds: i. the outer set 

 (andrczcium) , consisting of a few or many parts, the stamens] 2. 

 the inner set (gyncecium), consisting of a few or many parts, the 

 carpels. Separate carpels form simple pistils, but when several 

 are united they form a compound pistil. 



224:. The calyx, or sepals. The function of the sepals is 

 chiefly protective to the young stamens and carpels in the flower 

 bud. Where the corolla is absent, sepals are usually present, and 

 then they assume the function of the petals. (See also para- 

 graph 323.) 



225. The corolla, or petals. The petals are partly protec- 

 tive in the bud. But their chief function where well developed 

 seems to be that of attracting insects, which through their visits 

 to the flower aid in "pollination," especially " cross pollination" 

 (paragraphs 30 1-311). 



226. The stamens. The stamens are organs of the flower 

 for the production of pollen. The stalk (not always present) is 



