vi Peeface. 



and the emiscquent nfcessity of being in many places at abont the same time, 

 and. it can bo readily understood that the field work conld not be accomplished 

 in one or even two seasons. Indeed, it has reqnired several more than that. 

 Xotliing bnt a love of the subject would fortify one with the required patience. 



The necessity of visiting the trees in their native haunts is evident. This 

 has brouglit me much in contact with the country folk in remote regions aud 

 has been associated with many novel and generally pleasant experieuces. The 

 visit of an " outsider " ofttimes seemed as welcome an occasion to them as the 

 opportunities of their respective localities, and often contact with them, were 

 enjoyed liy me, and I gratefully remember many acts of kindness in these 

 hospitable people. 



Occasionally it was my good fortime to have the company of fellow botanists 

 in the field and enjoy the benefits of their familiarity with the trees of their 

 respective regions. Such was my experience in studying the interesting trees 

 of Statcn Island with Mr. Wm. T. Davis, for whose assistance I am very 

 grateful. 



A rare treat I found in store Avhen I dropped in upon Prof. C. D. Beadle, 

 botanist, at Biltraore, JST. C, and enjoyed a few days' sojourn with him working 

 n\) certain species of the Alleghany Mountains, and to Professor and Mrs. 

 Beadle I am under lasting obligation. 



For able counsel and assistance in many ways I am indebted to my good 

 friend. Prof. Wm. Trelease, director Missouri Botanical Garden. To Dr. 'N. M. 

 Glatfelter, whose familiarity with the Willows of Missouri was of material 

 assistance to me, I am likewise grateful. So, too, to Mr. G. W. Letterman, with 

 whom I made several visits to the valley of the ]\rerrimac River, ilo. I wish 

 to acknowledge favors extended by Mr. G. C. Laney and Mr. John Dunbar, of 

 Rochester, Prof. C. H. Peck, of Albany, and Mr. J. G. Jack, of the Arnold 

 Arboretum, in assistance to material illustrative of various species of Crata;gus 

 of their respective regions. To Mr. E. P. Clapp, Rev. E. J. Hill, Dr. J. 

 Sclmeck, J\rr. H. IvT. Patterson, Prof. B. O. Long-year, Prof. W. A. Buckhout, 

 Prof. A. T. Erwin, ]\rr. Y. R. Gardner, Mr. E. S. Steele, Mr. F. E. 

 Boyuton, i\rr. T. G. Ilarliison, Dr. R. M. Harper, Mr. B. T. Gault, Mr. F. K. 

 Balthis, ilr. A. .1. Johnson and 'Mr. J. C. Teas, I wish also to extend thanks 

 for assistance. Last, but by no means least, I gratefully acknowledge counsel 

 and facilities extended in the use of herbarium material by j\Ir. Giff^ord Pinchot 

 Forester, and Mr. G. B. Sudworth, Dendrologist of the IT. S. Forestry Service ■ 

 by Dr. J. X. Rose of the N'ational Llerbarium, and by Dr. IST. S. Britton 

 Director of the Xew York Botanical Garden. 



Data as to specific gravities of wo^ds has been taken from the Report of 

 Tenth Census of the United States, and represent in each case the average of 

 two or more determinations with absolutely dry wood taken from different trees. 



LowviLT.E, T\L Y., June 29, 1907. 



