198 



PHILOSOPHICAL NOTES ON 



Botanists look upon stipules as appendages of leaves, and, 

 indeed, Asa Gray, at p. 106 of his " Structural Botany," says : — 

 " Between salient expansions or wing-like margins of the base of 

 the 23etiole, such as those of the Saxifrage tribe, and stipules 

 adnate to the margins of the petiole, as in most Rosaceas, there 

 is no clear limitation. But presence or absence of stipules gene- 

 rally runs through a natural order.* Yet what are called stipules 

 in one order may pass for expansions or appendages of the petiole 

 in another." 



If we look upon the leaf as a special structure, unconnected by 

 inheritance with the stem, we shall often be puzzled to discover 

 the morphological position of this appendage called stipule. On 

 the contrary, if we look upon the leaf as a stem, and the axillary 

 bud as only a branchlel of the leaf, we shall, I think, more readily 

 be able to find the morphological position of the stipule. It would 

 be rather puzzling to make out how the spathe-like stipule of 

 Ficus elastica can be merely an appendage of the leaf rather than 

 of the stem and terminal bud. 



In the phasnogamous division of land plants we find such a 

 rich variety of the stipulary organs, often holding an important 

 functional position, that in many instances they take the place of 

 leaves. 



Fig. 55. Stipule of Potamogeton Rufescens (" Syme's Brit. Bot.," pi. 1402). 

 * Heredity readily accounts for this. 



