1-20 



ORGANOGRAPHY.. 



BOOK I. 



of the parenchyma of the leaves: in the 

 former case they project beyond the sur- 

 face or margin of the leaf, as in the Holly 

 (Ilex aquifolium) in the latter case they 

 are the veins themselves become har- 

 dened, as in the palmated spines of the 

 Barberry. The spiny petiole of many 

 Leguminous plants is of the same nature 

 as the latter. So strong is the tendency 

 in some plants to assume a spiny state, 

 that in a species of Prosopis from Chili, 

 of which I have a living specimen now 

 before me, half the leaflets of its bipinnate 

 leaves have the upper half converted into 

 spines. 



•2. Of Stipules. 



At the base of the petiole, on each side, is frequently seated 

 a small appendage, most commonly of a texture less firm than 

 the petiole, and having a tapering termination. These two 

 appendages are called stipules. They either adhere to the 

 base of the petiole or are separate ; — they either endure as 

 long as the leaf, or fall off' before it ; — they are membranous, 

 leathery, or spiny ; — finally, they are entire or laciniated. 

 By Link they have been called Parapliyllia ; an unnecessary 



