18 



tuberosa and the considerably harder and heavier wood of 

 Xylia dolabriformis. 



Finally the characteristic scent of the Teak wood should be 

 noted and compared, for example, with that of the wood of 

 Sandal, Toon and Deodar. 



The stem of our example, the Teak, of which we have now 

 shortly considered the most important and obvious characteris- 

 tics, may be taken as typical of the stems of the great majority 

 of the trees and shrubs of our forests, and some of the modi- 

 fications of this typical structure found in different species 

 have also been noted. It must be mentioned, however, that in 

 some species there is a remarkable departure from the type in 

 that there are narrow, more or less concentric, bands of soft, 

 bark-like tissue, alternating with bands of woody tissue 

 throughout the stem. These are found for example in 

 Dalbergia paniculata and Cocculus laurifolius. A similar 

 structure is often seen in the woody stems of climbers, e.g. in 

 Bauhinia Vahlii, in which the layers of porous wood alternate 

 with soft, red, bark-like tissue. 



If now we look at a section of a Deodar stem we find, 

 as before, a pith, distinct bark, and wood showing both 

 heart- and sap-wood, while in the wood are annual rings and 

 medullary rays. There is, however, a great difference from the 

 Teak wood in that here we have no pores, the annual rings 

 being marked by the darker colour of the denser wood on 

 the outside of each ring contrasting with the lighter colour 

 of that on the inside of the rings. This absence of pores is 

 characteristic of the wood of all the trees and shrubs commonly 

 known as Conifers. In some conifers, although there are no 

 Resin-o.uals. pores, there are w T hat are called resin-canals or -ducts, which on 

 a transverse section may at first be mistaken for true pores. 

 They may be distinguished by their irregular outline and they 

 are usually sparsely distributed through the wood. They are 

 well seen on a transverse section of Pinus longifolia. 



If now we look at the section of a Palm, e.g. Borassus 

 flabellifer, we find that there is no distinct bark which can be 

 stripped off and there are no medullary rays or annual rings. 

 Scattered throughout the soft tissue of the stem, we find 

 numerous rounded, hard, black areas, in the interior of some 

 Vascular o f which is a large pore. These are the so-called vascular 

 bundles. Those situated towards the exterior of the stem are 

 usually without pores and are closer together than those 

 towards the centre, and the outer portion of the stem is conse- 

 quently much harder and denser than the interior. The section 



