Explanation of the G-Trees 



MR. W. K. MAT I* ION, of the U. S. Forest Ser- 

 vice, who has recently spent several months 

 studying second-growth stands in the southern 

 pine belt of longleaf and slash pines, furnishes the follow- 

 ing explanation regarding the peculiar G-shaped trunks 

 of pine illustrated on page 

 423 of the July number of 

 Amkruax Forestry. 



" It is not uncommon in 

 second-growth longleaf pine 

 to come across trees with a 

 striking G-form section of 

 the main stem. The crook 

 usually starts at a point from 

 3 to 7 feet above the ground, 

 and after more or less of a 

 half circular sweep termi- 

 nates in an upward growing 

 stem at a point located 

 roughly over the initial point 

 in the basal portion of the 

 tree trunk. The explanation 

 lies in the death of the central 

 terminal shoot and the sub- 



HOW THE G-TREES FORM 



The contorted branches show the tendency of this permanently deformed 



longleaf pine to develop a vertical growing stem. 



aided by the increasing weight of the growing stem. In 

 perpetuating itself by means of a lateral branch, slash 

 pine (Pinus caribcca), formerly called Cuban pine 

 (Pinus heterophylla) by the U. S. Forest Service, makes 

 much less of a curving trunk, due undoubtedly to its very 



much faster growth. One 

 such case is illustrated in an 

 accompanying photograph. 

 " The dying of the central 

 terminal stem may be due to 

 any one of several causes, 

 including fire, insect attack, 

 and wind as the most com- 

 mon agencies. Occasionally 

 large sized groups of saplings 

 or small pole trees are thus 

 found topped off in the path 

 of a tropical hurricane. The 

 Nantucket tip moth 

 (Retinia frustrana Scud.), 

 which sometimes does much 

 harm to the young grow- 

 ing stems of shortleaf and 

 loblolly pines, seems to 



O-TREE OF NORTH CAROLINA, 

 The photograph of this specimen was taken by 

 P. T. iCneale. president of the Woodland Lumber 

 Company, of Philadelphia, near Princeton, North 

 Carolina, in 1912. There were a number of similarly 

 deformed trees in the vicinity. 



ONE FORM OF THE G-TREE 

 By the substitution of a lateral branch for the 

 killed central stem, this slash pine, in about 5 years, 

 has attained a height of 18 feet and a diameter of 

 6 inches at breast height. 



A WHITE PINE G-TREE 

 Harry D. Tiemann, of the Forest Products Labor- 

 atory, at Madison, Wisconsin, sends this photograph 

 of a white pine of G-tree shape on the banks of the 

 Wisconsin River near Kilbourn, Wisconsin. 



sequent effort of the tree to replace it by substituting one 

 of its laterals or side brandies. 



" Because of the slow-growing, flexible character of 

 its laterals and their characteristic nearly right-angular 

 forking, sometimes even forming a very acute angle 

 downward with the main stem, longleaf pine is particu- 

 larly successful in developing well-rounded G-shaped 

 substitute tree trunks. The full curving of the stem is 

 740 



accomplish very little injury to the large, well-protected 

 " asbestos " bud of longleaf pine. In isolated cases a 

 freak in burning would no doubt act as the initial cause 

 for the peculiar later development of the tree trunk. An 

 outbreak of some girdling insect working on saplings at 

 about a uniform height above the ground or a severe 

 wind storm offers the most likely explanation for the 

 occurrence in the July number of American Forestry." 



