CHAPTER IX. 



FLOWEKS AND THEIE WOKK. 



242. The Work of the Flower. We have already 

 examined the Broad Bean flower, and we have seen that 

 after a time nothing is left of the flower except (a) the 

 " young pod," which becomes greatly enlarged and contains 

 the seeds ; and (fe) the calyx, which remains as a cup round 

 the bottom of the pod. Evidently the great work of the 

 flower is the production of seeds. Are any other parts 

 besides the pistil concerned in this work, and, if so, what 

 share do they take in it? You have noticed the yellow 

 powder (pollen) which is produced in the anthers and is set 

 free when they open, and which is then found inside the keel 

 and on the upper parts of the pistil (style and stigma). Has 

 the pollen anything to do with the production of the ripe 

 pod and its seeds ? Would the pistil grow into a fruit, with 

 seeds, if no pollen came into contact with it ? 



(a) Effect of removing the Anthers. Flowers which have not 

 yet opened must be used in these experiments, because the anthers 

 burst and shed their pollen at an early stage. Remove the anthers, 

 making sure that you pick off the whole number, and that none of 

 them have burst already. To prevent pollen from reaching the pistil 

 from another flower, tie a small bag of paper or of fine muslin over the 

 antherless flower, which must, of course, be allowed to remain on the 

 plant. If the removal of the anthers has been carefully done, the 

 flower will open much as usual. Treat several flowers in this way, in 

 case any damage is done which might throw doubt on the results. 

 Are any seeds formed? Leave some of the antherless flowers un- 

 covered : do any of these produce seeds ? 



(&) Effect of removing the Stigma. You will have noticed 

 pollen adhering to the upper part of the pistil, i.e. the style, especially 

 to the tuft of hairs and the little terminal process (stigma) just above 



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