VALUE OF THE CONTEST 



Photographs Received by American Genetic Association Throw Light on Many 



Interesting Problems — Awakening of Public Interest in Large Trees 



Will Be of Great Benefit to Science 



W. H. Lamb 

 V. S. Forest Service, M'ashiiigtou, I). C. 



THE interest of the forester and 

 dendrologist centers upon sev- 

 eral features in the contest of 

 size amonj^ forest trees. What- 

 ever may be the interests of the inves- 

 tigators in other departments of biology 

 we are inclined to direct our attention 

 to the ascertainment of what species 

 reach the greatest size and of the max- 

 imum dimensions attained by every 

 species. It is also of importance to 

 consider the geographical location of 

 these individuals with respect to the 

 natural range of the tree. 



The location and identity of the larg- 

 est hardwood tree in the United States 

 is a matter of considerable scientific 

 and popular interest. Among conifer- 

 ous trees the first place in size has been 

 accorded the giant redwood of California. 

 The size and age of these trees have long 

 Vjcen a subject of great interest and 

 have offered many opportunities for 

 the free play of the imagination in 

 correlating different stages of the devel- 

 opment of one of these mammoth 

 plants to different periods of ancient, 

 mediev^al and modern history. Among 

 broad-leaf trees, however, no one species 

 stands forth as the colossus. The oaks, 

 the chestnut, the sycamore, the yellow 

 poplar, and a numljcr of other broad- 

 leaf trees all reach magnificent jjrojjor- 

 tions. It is rather difficult to com]jare 

 these trees in size. This is not only 

 true because of the necessity of com- 

 paring different species but also on 

 account of the variation in form among 

 individuals of a single sjK'cies. 



Every tree has a form which it assumes 



under normal conditions. In some 



trees, especially among conifers, this 



form, deeply imjjre.ssed for innumerable 



424 



generations, has become fixed and 

 hereditary to the extent that even when 

 grown in abnormal conditions, it will 

 assume the typical form. Very often, 

 however, the special type of growth is 

 not retained in a modified environment. 

 It is true, especially among broad-leaf 

 trees, that an immediate response to 

 the advantage of more space results in a 

 broad-headed and lateral growth which 

 is not characteristic of the tree in the 

 original forest where in dense stands a 

 long, clear trunk is developed, and where 

 lateral branches are suppressed. 



IN THE PRIMEVAL FOREST 



In the original hardwood forest of 

 eastern United States the yellow poplar 

 {Liriodendron tidipifera) and the syca- 

 more (Platanus occidentalis) probably 

 reached the greatest proportions. The 

 yellow poplar developed a clear trunk 

 and had a more uniform habit of branch- 

 ing than the sycamore; exceeded it in 

 height and from the lumberman's stand- 

 point was most desirable, since it would 

 saw out more lumber; but the sycamore, 

 although more irregular in habit, held 

 first place in size on account of the 

 massiveness of the branches, the ]jrimary 

 limbs of a very large sycamore fully 

 equaling an average forest tree in bulk. 



The Pacific coast forest is made 

 principally of coniferous trees, with 

 broad-leaf trees occurring as under- 

 growth or as scattered individuals, 

 and conspicuous only in valleys. The 

 forest of eastern United States, contain- 

 ing about half as many coniferous tree 

 s])ecies, has over four times as many 

 broad-leaf sjieeies as are found in the 

 western forest. It would bt' expected, 

 therefore, that competition in size 



