254 VEGETABLE ORGANOGRAPHY. 



disappears on reaching the apex : we -see this in Musa 

 Paradisiaca, Strelitzia, and several others. 



The beautiful family of Palms presents the two dis- 

 positions peculiar to curvinerved leaves. Those, with 

 leaves cut out so as to imitate pahnate ones, belong 

 to the division of converging curvinerved, and those the 

 lobes of which resemble those of pinnate leaves are of 

 the division of leaves with diverging nerves. 



The distribution of the stomata in leaves is connected 

 with that of the nerves. Among angulinerved leaves, 

 the nerves of which ramify much, forming more or less 

 irregular spaces, the stomata are scattered over the 

 limb ; on the contrary, in curvinerved ones, which have 

 for the most part the lateral nerves simple, or but little 

 ramified, the stomata are arranged in longitudinal rows 

 between each little nerve. 



The general form of the limb, which is so frequently 

 mentioned in botanical works, results from the dispo- 

 sition of the nerves, and its anatomical importance is 

 consequently much less than that of the cause which 

 produces it. There may be, and there are in fact, 

 ovate leaves formed by all the systems of nervation 

 which I have mentioned ; consequently it is not suf- 

 ficient in describing a leaf to mention its form, but its 

 system of nervation must especially and most expressly 

 be described. 



From this Section it may be seen that, although there 

 still remain some exceptions (especially among pedali- 

 nerved leaves), we can, however, easily distinguish the 

 structure of the limb of the leaf in the two great classes 

 of Phanerogamia : Dicotyledons are known by their 

 nerves on separating forming angles, whilst in Monoco- 

 tyledons they form curves ; the former are classed into 

 penninerved, palminerved, and pedalinerved leaves, but 

 their lateral nerves are always ramified after the system 



