AMERICAN FOREST TREES 687 



land by a fringe of lattice work of branches and stems, the marvelous 

 efficiency of the provision has been greatly increased in another way. 

 Suppose, for illustration, that cottonwood instead of mangrove formed 

 the protective thickets along stormy shores. The first hour of heavy 

 seas would reduce the trees to fragments. The weak, brittle trunks and 

 limbs would quickly break to pieces. But mangrove passes through 

 storm after storm unharmed. It is scarcely believable that accident 

 accounts for the fact that the best wood for the place is in the place; but 

 it is probable, rather, that ages of development and natural selection 

 gave to mangrove the qualities which make possible the accomplish- 

 ment of its work. It is one of the strongest, and as far as available data 

 may be depended upon, it is absolutely the most elastic wood in the 

 United States. Shellbark hickory is rated high in both strength and 

 elasticity; but mangrove rates higher. Sargent gives hickory's measure 

 of elasticity at 1,925,000 pounds per square inch; but mangrove's is 

 2,333,000 pounds. 



It is thus fitted in the highest manner to perform the work needed. 

 It plants itself in the right place; develops stems which will endure most 

 and suffer least; possesses enormous strength for resisting force, yet is so 

 extremely elastic that the force of waves is exhausted upon the trunks 

 and branches without flattening them upon the ground or crushing them. 

 Few things of the vegetable world show more perfect adaptation to 

 environment. The wood's very heaviness seems to add one more 

 quality fitting it for its place. When a trunk falls in the water, it does 

 not float away as most trees would, but sinks like iron, lies on the bottom, 

 helps to hold the forming island or bar in place, and in its death as in its 

 life it is a land-builder. , Its efficiency in that particular is increased by 

 the fact that it is little affected by marine borers which, in the warm, 

 brackish waters, usually destroy wood in a short time. 



Mangrove is not important commercially, though it is used for a 

 number of purposes. The wood weighs 72.4 pounds per cubic foot, takes 

 good polish, though it is inclined to check in drying; it contains many 

 small pores; medullary rays numerous and thin; color reddish-brown 

 streaked with lighter brown. The principal use of the bark is for tanning 

 and the trunks for piles. It is well fitted for fence posts, but not many 

 have been used in the region where it grows. It rates high as fuel, but 

 its great weight increases transportation charges if the haul is long. 



Tanbark peelers in Florida have cut much of the large mangrove 

 forest. They took the bark, and abandoned the trunks. There is no 

 likelihood that the species will be exterminated. Much of the growth 

 is practically inaccessible, and the trunks are too small to tempt bark 

 peelers, and cordwood cutters find plenty of material more convenient. 



