WOOD OF SOUTHERN PINES. 



Ill 



first ten to twenty years' growth, and in all cases tlie first few rings about the pith have but little 

 summerwood. In general, the summerwood per cent varies in the several species as well as in the 

 individual with the weight of the wood, which is least in the spruce pine, greatest in Cuban and 

 longleaf pine, and stands between these in loblolly and shortleaf. It furnishes a very useful 

 criterion to distinguish between these groups, and especially to select strong timber. 



In the limb, the summerwood is most abundant in the knot (all wood x^ractically partaking of 

 the character of summerwood, at least as far as the thickness of cell walls is concerned) and in the 



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Decades of Rings Tronv periphery . 



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Fig. 19.— Variation of summerwood per cent with rate of growth (width of ring) in tree No. 3, longleaf pine. 



Note — Only the heavy line represents summerwood per cent; the others indicate the actual width of the rin#» (uppwr pair) and of the 

 hand of summerwood (lower pair). 



part next to the stem, decreasing with the distance from the trunk. As might be expected, it also 

 forms a larger per cent of the wood of the underside of limbs and the concave portions of bent 

 trunks. 



GRAIN OF THE WOOD. 



Though usually quite straight grained, the wood of these species is by no means always so. 

 Spiral growth, leading to "cross-grained" lumber, occurs frequently, is usually more pronounced 

 in the basal portions of the tree, and commonly varies from pith to bark in the same log. Wavy 

 grain resembling that of the maple (curly maple) has not been observed, but an irregular wavy 

 grain, due to the fact that the surface of the trunk for many years is covered with small, low 

 eminences, 1 to a few inches across, is frequently seen, especially in longleaf pine, and leads to 

 remarkably pretty patterns. Unfortunately the contrast of spring and summer wood being so 

 very pronounced, the, figures are somewhat obtrusive and therefore not fully appreciated. 



