ON THE SUBSIDIARY USES OF STIPULES 195 



Legumino8ce , the stipules are often converted into 

 thorns, which are in some cases bent backwards so as 

 to aid the plant in climbing. 



As Reserves of Nourishment 



In Ghmnera, according to Reincke (25), stipules 

 serve as reserves of nourishment. 



As Holders of Rain 



Another use of stipules is to hold rain, as, for 

 instance, in some species of Thalictrum, Viola, and 

 Polygonum. 



The leaflets of Thalictrum (T. simplex) are so 

 arranged as to catch most of the raindrops ; they are 

 not wetted, however, by the rain, which runs off and 

 down the petiole to the cup formed by the stipules. 

 The stipules are fringed at the edge, which also assists 

 to retain the moisture. 



In some species of Viola also for instance, Viola 

 tricolor (Pansy) and the little yellow V. biflora the leaf 

 and leaf-stalk have a central furrow, down which the 

 water runs to the stipules, by which it is retained. 



The ocrea or sheath of the Polygonacece also serves 

 in some cases for the same purpose. This is well seen 

 in the large species, for instance, of Rumex and Bheum. 

 They will retain water for several days after the rain 

 has ceased. It is, however, gradually absorbed. 



In support of this view I may refer to the case of 



o2 



