THE LEAVES OF VASCULAR PLANTS. 283 



and they are wanting in all the Caryophylleas, Myr- 

 taceee, &c. 



The only thing which essentially characterises the 

 stipules, is their lateral position at the base of leaves ; 

 for otherwise all their other characters are very variable 

 in different plants ; and it is not impossible that we 

 might confound, under this common name, organs in 

 reality distinct. Their texture in several plants is per- 

 fectly foliaceous, and in this case they present all the 

 properties peculiar to leaves ; so that it might be said 

 that they are only small accessory ones, sometimes peti- 

 olate, more frequently sessile, sometimes entire, some- 

 times toothed or lobed, with pinnate or palmate nerves, 

 &c. ; but none are ever found to be compound, pelti- 

 nerved, or pedalinerved. 



They are frequently found membranous, as the leaves 

 themselves become in several plants ; and in certain 

 respects it might be said that these stipules are the 

 phyllodia of stipules, for they most commonly have an 

 enlarged base and longitudinal nerves, as petioles devoid 

 of limbs. 



It appears that some stipules degenerate into true 

 spines,^by becoming indurated ; such are those of Pictetia. 

 But it must be observed, that the name of spiny stipules 

 is sometimes given to different organs ; thus, in several 

 species of Acacia, such as A. pilosa and A. hcematomma, 

 we see at the same time on each side of the base of the 

 leaves a true stipiile, and a spine which is situated 

 below it, and is evidently a prolongation of the coussinet*' 

 of the leaf; w^hence we may conclude, from analogy, — 

 1st, that what are called the stipulary spines of the 

 MimoseaB, are not, as is believed, hardened stipules, but 



* This name is given to a little swelling of the stem, situated under the 

 leaf, and serving as a support to it. It is particularly visible in the Legu- 

 minosae. In Latin it is named pulvinus. 



