Chap. 56.] THE ROOTS OF TREES. 393 



thickness throughout. Some trees divide into branches from 

 the very ground, as in the apple-tree, for example. 



CHAP. 55. (31.) THE BARK OP TREES. 



In some trees the bark 60 is thin, as in the laurel and the 

 lime ; in others, again, it is thick, as in the robur ; in some it is 

 smooth, as in the apple and the fig, while in the robur and the 

 palm it is rough : in all kinds it becomes more wrinkled when 

 the tree is old. In some trees the bark bursts spontaneously, 

 as in the vine for instance, while in others it falls off even, as 

 we see in the apple and the arbutus. In the cork-tree and 

 the poplar, the bark is substantial and fleshy ; in the vine and 

 the reed it is membraneous. In the cherry it is similar to 

 the coats of the papyrus, while in the vine, the lime, and the 

 fir, it is composed of numerous layers. In others, again, it is 

 single, the fig and the reed for instance. 



CHAP. 56. — THE ROOTS OP TREES. 



There are great differences, too, in the roots of trees. In the 

 fig, the robur, and the plane, they are numerous ; in the apple 

 they are short and thin, while in the fir and the larch they 

 are single ; and by this single root is the tree supported, al- 

 though we find some small fibres thrown out from it laterally. 

 They are thick and unequal in the laurel and the olive, in 

 which last they are branchy also ; while in the robur they 

 are solid and fleshy. 61 The robur, too, throws its roots down- 

 wards to a very considerable depth. Indeed, if we are to be- 

 lieve Virgil, 62 the sesculus has a root that descends as deep 

 into the earth as the height to which the trunk ascends in the 

 air. The roots of the olive, the apple, and the cypress, creep 

 almost upon the very surface : in some trees they run straight 

 and horizontally, as in the laurel and the olive ; while in others 

 they have a sinuous course — the fig for example. In some 

 trees the roots are bristling with small filaments, as in the 

 fir, and many of the forest trees ; the mountaineers cut off 



60 It is evident that he. is speaking of the epidermis only, and not the 

 cortical layers and the liber. 



61 The roots of trees being ligneous, " carnosae," Fee remarks, is an in- 

 appropriate term. 



62 Georsr. ii. 291. 



