BOOK II. 



DEVIATIONS FROM THE ORDINARY FORM OP ORGANS. 



In a morphological point of view the form of the 

 various parts or organs of plants and the changes to 

 which they are subjected dmnng their development 

 are only second in importance to the diversities of 

 arrangement and, indeed, in some cases, do not in any 

 degree hold a second place. 



Taken together, the arrangement, form, and number 

 of the several parts of the flower, make up what has 

 been termed the symmetry of the flower.^ Referring 

 to the assumed standard of comparison, see p. 4, it 

 will be seen that in the typically regular flower all the 

 various organs are supposed to be regular in their 

 dimensions and form. At one time it was even sup- 

 posed that all flowers, no matter how irregular they 



' The word symmetry has been used in very diflFerent senses by different 

 botanists, sometimes as synonymous with " regularity," at other times 

 to express the assumed typical form of a flower. Payor understands it 

 to be that arrangement of parts which permits of the whole flower being 

 divided vertically into two symmetrical halves (bi-lateral symmetry). 

 Others, again, have applied the term symmetry to the number of the 

 parts of the flower, reserving the terms " regularity" or " irregularity" 

 for the form. It is here used in a general sense to express the plan of the 

 flower, and thus includes the arrangement, form, and number of its 

 component elements. 



