40 FIELD AND WOODLAND PLANTS 



of early flowers, and of tlie times of the appearance of the leaf in 

 our trees and shrubs, will prove of great interest when compared 

 with the corresponding events and times of other years. Not only 

 do our spring seasons vary considerably from year to year in such 

 a manner as to alter the general times of appearance of leaf and 

 flower, but the vicissitudes of our climate even change the order 

 in which these events occur. 



The general study of the buds of trees should commence before 

 they begin to burst. We commonly speak of the buds as winter 

 buds, but it should be known that they were formed in the preceding 

 summer or autumn, and have remained dormant throughout the 

 winter. There is usually a terminal hud at the tip of each twig, and 

 Icderal buds at the sides. If we examine a lateral bud we find 

 immediately beneath it a more or less distinct scar, denoting the 

 position of a leaf that fell in the autumn, thus showing that the 

 bud in question was formed in the axil or angle of the leaf. These 

 observations should be verified by examining the trees in autumn, 

 while the leaves still exist. 



It is not sufficient that we are able to recognise trees when 

 in leaf ; they should be known equally or almost as weU during 

 the wiiiter and early spring while the branches are bare, and this 

 is usually easily accomplished by making ourselves acquainted 

 with the general form of each tree as viewed from a distance, and, 

 on closer inspection, with the nature of the bark and the character 

 of the buds. 



All our forest trees are of the exogenous type ; that is, their stems 

 increase in thickness by the addition of new wood formed outside 

 the older wood and underneath the bark. Thus the bark, which 

 is composed of a layer or mass of dead, sapless cells, is gradually 

 pushed outward as the stem thickens. The result is that the bark 

 is either more or less fractured, as in the Elm and the Oak, or it 

 flakes off and falls to the ground, as is the case with the Plane and 

 the Bircli. A new layer of bark is always formed during each 

 summer, and this, in turn, either cracks or jieels away ; but while, 

 in the former instance, the accumulated bark presents a very rugged 

 appearance, and becomes very thick, in the latter case it remains 

 smooth, and is always thin. 



Then again, how are we to account for the great variety in the 

 general forms of our different trees — the irregular, crooked nature 

 of the Oak ; the slender, but denser branching of the airy Birch ; 

 and the tall, pyramidal form of the Lombardy Polar ? All this is 



