12 BULLETIN 1060, U. S. DEPARTMENT OF AGRICULTURE. 



tree soon after the seeds have been scattered by the wind, but some 

 cones may remain on the branches for a number of years. 



The root system is characteristically shallow. This is especially 

 true of trees on swampy soils where the roots spread out very close 

 to the surface; but on deep, porous soils they penetrate 4 to 5 feet 

 into the ground and occasionally as far as 12 feet. 



Characteristics of form are unimportant, with one exception, for 

 the recognition of this species. In general, the forest-grown trees 

 are tall, with open, conical crowns and long, cylindrical boles. 

 Their bases are very commonly heavily buttressed. Plates VI (fig. 

 3), VIII, and IX show the importance of this fact when form is con- 

 sidered. Plate IX, figure 2, gives one clue to its cause ; the stumps 

 illustrated in this plate were those of only two out of seven fully 

 grown trees that developed on this one windfall. Basal or butt swell 

 is common in this species and especially so in trees which occur on 

 the lowlands. Incidentally, it should be mentioned that this con- 

 dition in the tree very materially affects any diameter measure- 

 ments, for the standard practice in all species is to measure diameters 

 at a uniform height of 4£ feet above the ground, and this practice 

 would give very inconsistent results with large Sitka spruces. 

 Further discussion of this point appears under " Diameter growth." 

 The overmature trees present another characteristic, that of stag- 

 headedness. (PI. VI, fig. 2.) Such broken-topped trees are apt to 

 develop ascending side branches, and these may grow to 14 inches 

 and more in diameter and 50 feet in height. Trees in this condi- 

 tion, as shown by the cedar snags in Plate XIV, may be called 

 bayonet-topped. 



OCCURRENCE. 



Sitka spruce stands are found on a variety of sites but may be 

 grouped broadly into two classes — the bottomland or lowland, and 

 the slope or highland. The development of the tree, which to a 

 great extent is influenced by the amount of soil moisture, is the chief 

 difference between the two types, and the altitudinal situation is of 

 only minor consideration. The forest may be of pure spruce or of 

 spruce in mixture with other species. These types occur throughout 

 the range of the species, and a third or " upper slope " type might 

 be added for Alaska to include the bodies of scrubby spruce near the 

 upper altitudinal limit of tree growth. 



BOTTOMLAND TYPE. 



This type is found in the moist situations of river bottoms and 

 benches above the river beds where there is a deep, rich alluvial soil, 

 and where in places the heavy precipitation of the winter and spring 

 months has so saturated the ground that standing water is not un- 



