TREES AND THEIR LIFE PROBLEMS. 



As we walk along the streets or wan- 

 der in the woods, admiring the dignity 

 and gracefulness of the trees, few of us 

 stop to realize the cost. We appreciate, 

 in a measure, the cost of a cathedral, for 

 who has not watched a building grow, 

 stone by stone or brick by brick, until the 

 last portion is in place? We appreciate 

 fairly the cost of a human life, since we 

 have so often seen the long and tedious 

 struggle of the child, journeying toward 

 maturity ; we know of a surety that 

 not only the child himself, but also his 

 kinsfolk and friends have a weighty place 

 in the struggle for manhood. We real- 

 ize to some extent that animals attain 

 maturity only through many severe 

 struggles. Yet how few among the 

 many have any conception of the fierce- 

 ness of the conflicts which trees are 

 obliged to meet on every hand. Nor is 

 the market value of the tree any index 

 of the cost, as would be true of an artifi- 

 cial structure. It will be the mission of 

 the following paragraphs to unfold some 

 of the problems which trees are obliged 

 to face in their long and strenuous battle 

 of life. In considering this topic, trees 

 will first be regarded as individuals, while 

 in the later paragraphs, the social life of 

 trees will be considered. 



One of the most obvious and impor- 

 tant factors in the life of trees is their 

 relation to light. Those who are at all 

 familiar with plants are well aware that 

 the production of the green coloring 

 matter, which characterizes far the larger 

 part of the plant world, is quite depend- 

 ent upon light. Where growth takes 

 place in the dark, as in the case of pota- 

 toes sprouting in a dark cellar, or inside 

 of a head of cabbage, the green color 

 fails to appear; the blanching of celery, 

 when the stalks are buried, illustrates the 

 same phenomenon. Similarly, if a tree 

 branch be covered by soil, or enclosed in 

 a dark chamber of any kind, the green 

 color fails to appear, exactly as in the 

 more familiar instances just enumerated. 

 If light should be excluded from all of 

 the branches, the entire tree would be 

 lacking in the green coloring matter, and 

 after a time the tree would die. A care- 



ful study of such phenomena as these 

 would show that the tree had starved to 

 death. Thus we arrive at the important 

 conclusion that for a tree to secure its 

 food supply, it must be exposed to a cer- 

 tain degree of light, and must possess 

 green coloring matter, the so-called 

 chlorophyll, which is also dependent upon 

 light for its existence. If we accept 

 these statements as proven, and they have 

 been demonstrated over and over again, 

 it becomes easy to realize the great ad- 

 vantages which trees possess as com- 

 pared with other plants. If light is 

 necessary in the life of plants, those 

 plants which are tallest and branch the 

 most may be regarded as best fitted, so 

 far as this factor is concerned. One has 

 but to make a careful study on a bright, 

 sunny day to assure himself of the won- 

 derful perfection of the tree, as a light- 

 receiving mechanism. In all of the vast 

 mass of foliage, there is scarcely a leaf 

 that fails to receive the direct rays of the 

 sun during some period of the day. In 

 trees which have small leaves like the 

 pine, or finely divided leaves like the 

 honey-locust, the rays of light are sifted 

 down through the branches for a consid- 

 erable distance, upon the leaves beneath. 

 In trees with relatively large leaves, like 

 the ' linden or catalpa, the leaves are 

 placed far enough apart, so that" some 

 direct rays are reasonably sure of strik- 

 ing them. One standing at the base of 

 one of these latter trees, and looking up 

 toward the sky, will see a most marvel- 

 ous adjustment of the leaves to one 

 another, a utilization of all of the avail- 

 able space, and the formation of what 

 has been termed a leaf mosaic. Green 

 plants that are not trees may be divided 

 into two classes, those which endure 

 shade, and those which require sunlight. 

 This latter class may be regarded as in 

 a state of constant but hopeless conflict 

 with the trees ; that is, this conflict may 

 be regarded as hopeless so long as the 

 light relation is the decisive factor, since 

 trees are better able to secure light than 

 are the plants which grow beneath them. 

 With shade plants, of course, the tale is 

 very different, since they can secure an 



