Introducioi-y View of the Natural System of Plants, 35 



from the base to the apex, in Dicotyledones they diverge from 

 the midrib towards the margin at various angles ; in the for- 

 mer they are branchless, the principal veins being con- 

 nected by nearly simple secondary veins ; in the latter they 

 are much branched, ramifying in many directions, and giving 

 the surface of the leaf a netted appearance. 



Such are the very obvious distinctions of the two great 

 classes of Phanerogamous, or flowering plants; and so far 

 is it from there being any necessity for dissecting a seed in 

 order to ascertain its structure, that this point is one of the 

 most easy determination, and about which there cannot be in 

 one case in five hundred the slightest cause of doubt or diffi- 

 culty. It is almost impossible to take even a morsel of a 

 plant in the hand without instantly being in possession of the 

 knowledge of the structure of its seed, with respect to the 

 cotyledons. 



Thus far have we advanced without a single obstacle to 

 impede us. In all farther investigation no greater degree of 

 knowledge or application is requisite, than what ought to be 

 possessed by every one who would be able to ascertain the 

 genus of a plant. Many of the orders do not depend upon 

 the minute characters of the seed so much as is believed ; the 

 structure of the ovarium and position of the ovula are aids 

 which frequently make amends for the absence of fruit : and 

 the nature of the foliage and inflorescence are guides which, 

 though sometimes treacherous, are often as faithful as the 

 fructification itself. But as it is not intended to give the 

 characters of the orders in this place, neither is it necessary 

 to advance farther in an explanation of the manner of deter- 

 mining them ; upon that point each order would require a 

 particular note. It may however be confidently believed that 



V, Transverse section of a dicotyledonous'stem. y. An embryo with many cotyledons. 



w. An embryo with two cotyledons. ' x. Stem and leaves of a dicotyledonous plant. 



X, An embryo with four cotyledons. 



D 2 



