240 VEGETABLE ORGANOGRAPHY. 



petiole is bordered : such is, for example, the petiole 

 of Lathyrus articulatus. This marginal limb is endowed 

 with all the properties of the ordinary limb, and may 

 replace it, physiologically speaking. It is likely that 

 that wliich is called the leaf in the Nepenthes, is a bor- 

 dered petiole, and that the true limb is the terminal 

 cup. It is possible that, in the Dioncsa, the name of 

 Bordered Petiole ought to be given to the lower part of 

 the leaf, and that of Limb to be reserved for the two 

 irritable lobes. The marginal limb of bordered petioles 

 differs in general from the ordinary limb, in not having 

 lateral projecting nerves, but only anastomosing veins. 

 In compound leaves, if the petiole be bordered, as fre- 

 quently happens, the border is interrupted at each arti- 

 culation when the leaflets are opposite. Thus, for 

 example, in some species of higa, or in Fagara pterota, 

 the petiole is composed of as many joints as there are 

 pairs of leaflets, and each joint is bordered by a folia- 

 ceous wing. 



Let us suppose now, as frequent examples are found 

 among compound leaves, that all the lateral leaflets are 

 wanting ; two things will happen : — If there be no ter- 

 minal leaflet, the leaf will be found composed of joints 

 placed end to end ; this is what is called a LomenTa- 

 ceous Leaf, and of which a Bignonia (PI. 10, fig. 2), 

 discovered in Madagascar by Noronha, affords an ex- 

 ample. Such a leaf is nothing but a petiole comjDosed of 

 bordered joints, the leaflets of which have not been 

 developed. If the terminal leaflet exist, there is some- 

 times a bordered petiole terminated by a single leaflet; 

 this takes place in the Orange, Citron, Desmodium tri- 

 quetrum (PI. 10, fig. 3), &c. Sometimes a cylindrical 

 petiole, terminated by a leaflet also cylindrical, as in 

 Sarcophylliim (PL 10, fig. 4) ; sometimes, and this is the 

 case most frequently, an ordinary petiole, terminated 



