S88 VEGETABLE ORGANOGRAPHY. 



to them : those which are foliaceous' cooperate in the 

 elaboration of the^juices ; those which are changed into 

 spines, "serve for the defence of the plant. 



Section IX. 



Of the Union of Leaves with each other and with other 



Organs. 



Leaves are organs which unite with the greatest 

 facility both with one another and vsdth the stem or 

 pedmicles. 



When two leaves are found very near together at 

 their margins, at the period of their development, they 

 join together, as is frequently seen in purely accidental 

 cases; thus I have figured an example of the Laurel, 

 (PL 14, fig. 1,) and another of Justicia oxyphylla, 

 (PI. 14, fig. 2,) and there is no botanist who has not 

 found analogous ones in different plants. There are 

 plants in which this phenomenon, instead of being acci- 

 dental, is more or less constant ; thus, opposite leaves 

 are very frequently united by their bases, so that they 

 seem to form a single disk pierced by the stem ; this is 

 seen in Crassula perfossa, Sylphium perfoliatum, and in 

 the upper leaves of several Honeysuckles {Lonicera). 

 In these last, in particular, the fact is the more striking, 

 as in following the leaves from the base upwards we 

 can see all the degrees, from those perfectly free to those 

 which are completely united. To these opposite leaves 

 united at their base the name of Connate {folia con- 

 natd) is given. When the leaves are verticillate they 

 can also be united together, so as to surround the stem 



I 



