CONIFEROUS FORESTS 357 



tree over several acres, especially in Okefinokee Swamp, where it seems 

 to attain its maximum dimensions. 23 



It grows in poor soils, usually sand, inundated part of the year, but 

 rarely if ever to a greater depth than five or six feet. (High- water 

 mark is indicated by the height of the enlarged base of the trunk rather 

 than by the knees, which are less characteristically developed in this 

 species than in T. distichum.) Its favorite habitats are shallow ponds 

 which dry up in spring, and the swamps of coffee-colored (i. e., not 

 muddy) creeks and small rivers. The regions where it grows have an 

 average temperature of 60°-75°, a growing season of 240 to 360 days, 

 and an annual rainfall of 40 to 65 inches, over 40 per cent, of which 

 falls in the four warmest months, June to September. 



The pond cypress has a thicker bark than its better-known relative, 

 and mature trees are practically immune to fire. The ponds in which 

 it grows are likely to be swept in the dry season by fire, which chars the 

 bark at the bases of the trees a little, but does no perceptible harm. 



The wood is very similar to that of T. distichum (a little stronger 

 and heavier, if anything), and not satisfactorily distinguished in the 

 lumber trade, but the tree is usually too small, crooked or hollow to be 

 worked up into lumber profitably. It is used principally for shingles, 

 posts, poles, piles, cross-ties, etc. No statistics of its production are 

 available, but it is evidently cut most extensively in Georgia and Florida. 



The Southern Spruce Pine (Pinus glabra) is sometimes called white 

 pine, or "bottom white pine," on account of its resemblance to the 

 well-known northern tree, to which it is not very closely related, how- 

 ever. It ranges from southern South Carolina to central Florida and 

 eastern Louisiana, in the coastal plain, and never forms pure stands, but 

 associates with hardwood trees, especially the magnolia. It prefers soils 

 well supplied with humus and protected from fire, like the white pine 

 and hemlock, and is usually found in hammocks. 



Its wood is softer than that of most other southern pines, and might 

 be used as a substitute for white pine if it were more abundant and 

 better known. 



The Slash Pine (Pinus Elliottii) is also strictly confined to the 

 coastal plain, ranging from southern South Carolina to southeastern 

 Mississippi, inland about 165 miles in Georgia, and southward to about 

 latitude 27° in Florida. It is sometimes the only tree on several acres, 

 but is commonly associated with the pond cypress just mentioned, in 

 shallow ponds or in swamps of small streams that are never muddy. 2 * 



23 See Science, II., 17: 508, March 27, 1903; Bull. Torrey Bot. Club, 32: 

 113, 1905; The Popular Science Monthly, 74: 603, 604, 607, 612, June, 1909; 

 The Auk, 30: 485-487, October, 1913. 



24 There is an illustration of a forest of this species in the The Popular 

 Science Monthly for June, 1909, p. 607. 



