ORDER RUTACE^E, OR RUE TRIBE. 415 



but it is not placed in that division of the group, since in its 

 general structure it is so closely allied to the Rutaceae, that it 

 cannot be separated from them. 



579. The principal habitation of the Rue tribe is the South 

 of Europe, whence it extends through the temperate portion of 

 the Old World, rarely advancing within the tropics. The 

 common Rue was formerly much esteemed in medicine ; it was 

 mentioned with approbation even by Hippocrates, and for many 

 centuries it was considered a preventive of contagion, and was 

 known under the name of " herb of grace." It is now, how- 

 ever, seldom employed, except by village doctresses. 



580. The following table* will be found to express, in a con- 

 cise form, the most evident points of difference among such of 

 the foregoing orders as contain Plants found in Britain ; so that 

 the Student will have little difficulty in assigning to its correct 

 place a specimen of any one of them, which he may meet with. 

 It is to be remembered, however, that there are orders of minor 

 importance, which are not altogether excluded by these characters, 

 and that the specimen may belong to some of them. But as all 

 those which include the commonest wild and garden flowers have 

 been adverted to, this is not likely to happen. 



CLASS EXOGENS. SUB-CLASS THALAMIFLOR.E. 



Flowers possessing calyx and corolla, the latter composed of 

 distinct petals. Stamens, as well as petals and carpels, arise at 

 once from the disk ; except when sometimes slightly adherent to 

 the sides of the ovary. 



A. Stamens more than 20. 

 a, Ovary superior. 



a, Leaves without stipules. 



Carpels distinct Ranunculaceae , 504. 



Carpels united ..... Papaveracece, 523. 



* By the use of such a table as this, almost any British plant may be referred, 

 with great facility, to its proper Order in the Natural System. For example, we 



