of British Plants. 605 



The chief object of this arrangement is simplicity; and is 

 so far, for the junior student preferable to those hitherto adopt- 

 ed, which, although perhaps more scientific, are yet difficult 

 and almost useless until he has acquired some experience in 

 the science. Perhaps this is is not better illustrated by any 

 order than Crucifera (Brassicacea), in which, according to 

 the Synopsis of Dr. Lindley, (the one most generally and de- 

 servedly made use of), the student has first to determine to 

 which of the sub-orders his plant is referable, these divisions 

 being founded upon the position and direction of the radicle 

 and cotyledons ; as, — 



Pleurorhizece,... Radicle applied to the edges of the cotyledons. 



iy , i • f Radicle applied to the back of the cotyledons; cotyledons 



[ licit. 



n 7 7 j Radicle applied to the back of the cotyledons ; cotyledons 



urthoplocea, .. j folded lengtllwise# 



To arrive at this determination is often a matter of no small 

 difficulty and uncertainty, and indeed, in many cases, cannot 

 be effected without very careful dissection and microscopic 

 assistance ; and unless the plant in question can be satisfac- 

 torily classed under one of these (the sub-orders), no assist- 

 ance can be obtained by reference to the " tribes," since the 

 distinguishing characters of those ranked under Pleurorhi- 

 zece, are also common to Notorhizece and Orthoplocew. 



For the purpose then of assisting in the removal of these 

 difficulties, and more easily determining the names of genera 

 and species, whenever either are unusually numerous, I have 

 applied the arrangement here introduced to the natural orders 

 Cruciferce, Labiates, Leguminosce, Umbelliferce, Graminacea, 

 the genus Carex, &c. &c, as perhaps offering more difficul- 

 ties than any others that come under the observation of the 

 student of English Botany. 



The application of the following tables is sufficiently obvi- 

 ous ; it is only necessary to begin by comparing the plant (of 

 which the generic name is required) with the characters given 

 in the first binary division, A, from whence reference is made 

 to other divisions, until its correspondence with the essential 

 features there expressed at once points out its name. Thus, 

 in the cruciferous genus Barbarea, it is readily seen that it 

 possesses the peculiarities contained in the second line of the 

 first division ; which, having the letter B affixed to it, indi- 

 cates that a further description is contained in the division of 

 that name ; here it is but necessary to determine whether the 

 sepals of the plant are patulous or connivent, when the for- 

 mer being found to be the case, it is only required to pass to 

 the division pointed out by the letter placed against the line, 



3n2 



