THE LEAVES OF VASCULAR PLANTS. 285 



are some also among membranous ones, and especially 

 spiny ones, which remain after the fall of the leaves ; 

 this is observed in several woody Rubiacege, in Ery- 

 throxylon, &c. 



One of the most remarkable differences which stipules 

 present, when compared together, is the various manners 

 in which they adhere either to the petiole or to each 

 other. 



With regard to the first, stipules are said to be Peti- 

 OLARY, when by their inner side they are more or less 

 joined to the petiole — as, for example, vaRosa, TrifoUum, 

 &c. ; they are called Caulinary when they do not 

 adhere to the petiole, as in Vicia. Petiolary stipules, 

 on account of their adherence to the petiole, have in 

 general the same duration as the leaf; caulinary ones 

 are those alone among which we find remarkable varia- 

 tions of duration, that is to say, which can either fall off" 

 early or continue after the leaves. 



Those which arise on both sides of the leaf are some- 

 times so large that they are united together at the oppo- 

 site side of the stem ; then the two stipules seem only to 

 make one opposite the petiole ; and as this union is rarely 

 complete, the portions which remain free at the apex 

 may appear as two teeth or lobes ; and it is usual to 

 say, that this pretended single stipule is emarginate, or 

 bifid : this we see in several species of Astralagus, which 

 form the sections of A. synochreati and hypoglottidcei. 

 On comparing together the species of these two sections, 

 we may remark all the difiTerent degrees of their junction. 

 All stipules said to be opposite the leaves, appear to be 

 formed in the same manner ; when they do not present 

 any emargination, we may judge of them by analogy, 

 and by the disposition of the nerves : these stipules are 

 found in Magnolia, Ricinus, certain species of Ficus 

 (PI. 6.) &c. 



