12 BULLETIN 680, U. S. DEPARTMENT OF AGRICULTURE. 



bearing only, are small yellowish bodies attached by threadlike 

 stems. The cones of the hemlocks mature in one season, and are 

 composed of thin overlapping scales, beneath each of which two 

 winged seeds are borne (PL IV, a) ; only the scales in about the cen- 

 tral half of the cones, however, bear fertile seeds, those above and 

 below this part being imperfect. The seeds of hemlocks are peculiar 

 in having minute resin cells at various points on the outer surface. 

 The small light seeds are easily wafted by the wind and thus may be 

 widely disseminated. The seed-leaves of our native hemlocks are 

 from 3 to 4 in number and very short. 



Hemlocks are important forest trees, both for saw timber and for 

 tan bark. As yet their wood is of comparatively lower commercial 

 value than that of the pines, firs, and spruces, which often grow with 

 hemlocks. Unquestionably, however, the commercial importance 

 of hemlock wood, particularly of the western hemlock, will be greatly 

 increased as the supply of other timbers, abundant now, is reduced. 

 Strangely enough, the superior quality of western hemlock timber 

 has long failed to be fully appreciated because the wood has been 

 assumed to be similar in quality to that of the eastern hemlock, to 

 which the western wood is vastly superior. 



Four species of hemlock are indigenous to the United States and 

 adjacent portions of Canada. Two of these inhabit eastern United 

 States and adjacent Provinces of Canada, and two are found in the 

 north Rocky Mountain and Pacific forests. 



The hemlocks are of ancient origin, remains of them having been 

 found in the Miocene formation of Europe and Asia. Tsuga mer- 

 tensiana, the mountain hemlock, has been found in the Pleistocene 

 of Alaska. 18 



WESTERN HEMLOCK. 



Tsuga heterophylla (Raf.) Sargent. 



COMMON NAME AND EARLY HISTORY. 



Western hemlock is known to laymen chiefly as " hemlock." 

 From its very close general resemblance to the familiar eastern 

 timber hemlock {Tsuga canadensis Carr.) many of the early settlers 

 in the Northwest believed the western hemlock to be the same as the 

 eastern species. The common name " western hemlock" is here 

 adopted in order to prevent confusion of these trees, which are 

 botanically distinct and, as northwestern lumbermen well know, 

 very unlike in the qualities of their woods. 



The British navigator George Vancouver gives the first published 

 notice of this tree in 1798, in his narrative of a voyage 19 to the north 

 Pacific coast, in which he mentions "the Canadian and Norwegian 

 hemlock," a name that can refer only to the species we now know 



!8 Fide Dr. Edward W. Berry; see footnote No. 4. 



19 Voyage of Discovery to the North Pacific Ocean and Round the World (1798). 



