THE FLOWER 23 



foliage leaves had replaced all the floral members within the 

 calyx and the end of the axis had become much swollen. It is 

 probable that the latter fact was responsible for the former, and 

 that a growing axis put forth leaves, as it usually does ; but the 

 inference that these leaves represent the replaced floral mem- 

 bers in any morphological sense has no logical connection with 

 the facts observed. Such cases as that of the ordinary flowers 

 of Nymphaea, in which stamens seem to be gradually differ- 

 entiated from petals, present no difficulty when one notes the 

 remarkable indifference of sporangia to the nature of the mem- 

 ber upon which they appear. Because microsporangia appear 

 occasionally upon an axial structure it might as well be argued 

 that stamens are transformed stems. The stamens and carpels 

 are just as definite morphological structures as are foliage 

 leaves, with just as distinct functions, and should be so re- 

 garded, whatever may have been their historical origin. Stamen 

 and leaf probably merge into one another in history, and so 

 do stem and leaf, but all have become established as distinct 

 organs. 



Further details as to the varying form and structure of 

 sepals and petals are of no special morphological significance, 

 and are of interest chiefly to the taxonomist and the ecologist. 

 The stamens and carpels, however, are so intimately associated 

 with essential morphological structures that some further de- 

 tails in reference to them are necessary. 



The stamen set has been called collectively the " androe- 

 ■cium," a name so objectionable to the morphologist on account 

 of its sexual significance that it should be abandoned. The 

 stamen is an organ devoted to the production of microsporangia, 

 and its endless diversity of form and position is related more 

 or less directly to the needs of pollination. The term " anther " 

 is one of convenience, but represents a morphological complex 

 made up of sporangia and more or less sporophyll tissue. The 

 cooperation of sporophyll and sporangia in the dehiscence of 

 the latter will be included in the discussion of the microsporan- 

 gium, as well as those various differences among anthers that 

 have to do with the number and behavior of their sporangia. 

 It is important to note that stamens have the power of branch- 

 ing, and can thus multiply sporangia. Well-known cases are 

 ■Callothamnus, in which the branching is like that of a joinnate 



