1891.] 1-^1 [Rothrock. 



white oak, rock oak, pitch pine, shellbark and pignut hickory, black walnut, 

 locust and chestnut. Of these tiie white pine is a tree of wide geographi- 

 cal range, and of equally wide powers of adaptation to conditions of soil 

 and climate. Originally it grew more or less commonly through the 

 State from the northern to the southern boundary, and most abundantly 

 along the central meridian. It is especially noteworthy that though its 

 favorite locality was on the higher, poorer soils, where, when once 

 cleared, the land had little agricultural value, that it still grew luxuri- 

 antly on some of the lower, richer lands. What the original rate of re- 

 production over most of its area was cannot now be answered with cer. 

 tainty. It is, however, safe to say that on the soil best adapted to its 

 growtii in the central part of Pennsylvania, one may expect to see a tree 

 of this species grow in from fifty-five to sixty-five years to a diameter at 

 two feet above the ground of from eighteen to twenty-two inches. Such 

 limber is not mature. An inspection of the stump of one felled at this 

 age will reveal the fact that the tree was then in the most productive 

 period of its growth, and hence that it was poor policy to sacrifice it then. 



The hemlock prefers the rocky sides of our mountain gorges, or a rocky 

 hillside overlooking a stream. Occasionally it appears in a deep forest on 

 a flat by a stream. It is very scarce along the southern border of the 

 State except in the mountains proper, where it extends its range to the 

 south. 



If it were required to select a single tree which should be peculiarly 

 representative of Pennsylvania the hemlock would probably most fully 

 be so. Here to a greater extent than in any other State it has been an 

 important tree in our lumbering interests, and no less important in the 

 manufacture of leather. Here also its most reckless destruction has been 

 witnessed ; where miles of matured hemlock forest have been absolutely 

 sacrificed for the bark alone. In this State also there are probably more 

 miles suited to reproduction of hemlock than in any other Northern State. 

 In some respects the hemlock is peculiar; for example, the nurseryman 

 finds no great trouble in raising it, growing it into hedges or even into 

 isolated trees. Yet the experience of our lumbermen and the few who 

 have tried to restore it as a forest tree has not been encauraging. Of 

 course there are reasons for the diff"erent results, mainly due to the fact 

 that the forester works under conditions which are inimical to its growth 

 and which, to a large extent, the nurseryman can avoid. Still the fact 

 remains that the hemlock is among the slowest of our forest trees in its 

 early growth, and when the .shade under which it originally grew is de- 

 stroyed the difficulties of its reproduction are immensely increased. It is, 

 however, of the utmost importance to the C(>mmonwealth that its resto- 

 ration be attempted, first, because of its intrinsic value ; second, because 

 it grows and thrives on land which, but for it, would be almost valueless. 

 The hemlock is, as a rule, a tree liaving but little tap root. Its roots 

 spread out along or just beneath the surface of the soil. Yet as one of 

 the biological marvels connected with this wonderful tree, it will often be 



PROC. AMER. PHILOS. SOC. XXXIII. 144. P. PRINTED MARCH 24, 1894. 



