Morphology of the Citrus. 211 



In Asa Gray's "Structural Botany," page 171, is 

 given a monstrous flower of white clover, after 

 Turpin, in which "the pistil is stalked, and the 

 ovary open, and the margins bearing leaves instead of 

 ovules." 



As the plumule of the seed, which is the developed 

 ovule, is homologous to a branch, and as this branch, 

 according to the monstrous clover, can be transformed 

 into a leaf, it is reasonable to infer that the normal 

 leaf is probably nothing but a transformed branch, 

 arrested in its growth and turned to other pur- 

 poses. The leaf-like branch of Ruscus androgynus 

 would perhaps give a better idea of what I mean 

 by comparing the leaf of the citrus to a modified 

 branch. 



The abnormal Begonia alluded to, shows the same 

 transformation, viz., of ovules changed into stamens, 

 which in their turn are modified leaves, and are often 

 changed into petals or leaves. 



According to this mode of reasoning therefore, the 

 leaf of the citrus, would be a modified branch, the 

 serrations on its edges, abortive leaflets, the oil cells in 

 their angles, abortive buds, in abortive axillae ; and to 

 conclude, the normal bud, the spine, the oil cell of the 

 leaf and the rind, the juice vesicles of the pulp, the 

 pollen grains, and the seed-bud would all have to be 

 considered as homologous. 



It is true the leaf is often deciduous, while the 

 branch is not, but the flower and the fruit, which are 

 admitted to be modified branches, are also mostly 

 deciduous, when their function on the tree has been 

 completed. Moreover, the leaf, or as I take it, the 

 modified branch, after it has completed its special 

 function, is more serviceable to the tree off than on. 

 The old persistent leaves, besides absorbing some of 



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