14 



Shape of 

 Stem. 



Stem 



Structure, 



Bark. 



forest trees, the smallest branches which have been produced 

 most recently are called twigs, the smaller branches branchlets, 

 and the larger ones branches. 



16. The shape of the stem and 



branches varies considerably in different plants and often helps 

 the Forester to distinguish his trees in the forest. Many trees 

 have large buttresses at the base of the trunk, e.g. Bombax 

 malabaricum, see Fig. 4, Plate XI. In Ougeinia dalbergioides 

 the stem -is usually short and almost always crooked. In 

 Acacia leucophloea it is almost always crooked and knotty 

 (gnarled). In the Hornbeam. Carpinus viminea, it is distinctly 

 fluted, i.e. with broad, shallow, curved grooves. 



In many plants the stem is cylindrical, i.e. terete, in 

 others the stem has 3, 5, or more distinct ridges or angles. 

 Sometimes, in addition to being angled, the stem is more or 

 less deeply grooved, or hollowed out between the angles, and 

 it is said to be channelled. If the stem is marked with more 

 or less parallel furrows it is sulcate, if the furrows are very 

 minute and look like mere lines the stem is said to be striate. 

 The stems of lianes are frequently irregular in shape and are 

 flattened or deeply grooved. 



Such peculiarities, although as a rule not noticeable on 

 the old stems and branches of trees and shrubs, are often very 

 characteristic of branchlets and twigs. The branchlets of 

 Flemingia stricta, for instance, are 3-angled (triquetrous), those 

 of Coriaria nepalensis are quadrangular, those of Teak are 

 channelled, and those of Flemingia congesta are sulcate. 



17. If .now we cut through 



a stem of one of our common forest trees, say the Teak, 

 and examine the cut surface, we find the greater portion 

 of the interior of the stem to be solid and hard, consisting 

 of the so-called wood', which is enveloped in a comparatively 

 thin external coat of softer substance of a different colour, 

 which can be detached from, and stripped off, the solid woody 

 cylinder which it covers. This outer coat is the so-called 

 cortex, or bark, of the Forester ; its characteristics vary greatly 

 in different species and the Forester finds them very valuable 

 for the identification of trees in the forest. In some plants, 

 e.g. Palms and Bamboos, there is no true bark. The first 

 characteristic of the bark to be noted is its thickness ; on the 

 stems of young plants and the twigs of old plants it is very 

 thin. On the old stems of trees and shrubs its thickness varies 

 greatly in different species. Thus in Ougeinia dalbergioides it 



