. This difference in rate of growth is attended by a corresponding 

 difference in the form of the young trees. The rapid-growing coast 

 fir produces long, slender branches, at relatively wide intervals on the 

 main trunk. They leave the stem at a rather acute angle, but are 

 often gradually curved by their own weight toward a horizontal posi- 

 tion. The mountain form has shorter, comparatively stiff branches, 

 which are closer together and tend to maintain the direction in which 

 they start from the trunk. The compact, upright crown of the moun- 

 tain fir and the more open, drooping appearance of the coast form 

 are contrasted in figure 1. 



The more rapid growth of the coast form is achieved partly by the 

 production of a second " leader," or main growing shoot, in the 

 autumn, while the growing season of the Rocky Mountain form comes 

 to an end earlier in the year. The early termination of its growth 

 period allows the Rocky Mountain form to harden its wood before 

 the first severe frosts, an advantage which is lost to the coast fir, with 

 its succulent autumn shoot. This characteristic prevents the cultiva- 

 tion of the otherwise more desirable coast form in some places. 



In Europe the terms " green " and " blue " Douglas fir are often 

 applied to the coast and mountain forms, respectively, because the 

 leaves of the former are dark green, while those of the mountain 

 form are often bluish like the foliage of blue spruce {Picea parry ana). 

 This blue tint is not constant, however, and may be very pronounced 

 in some specimens and entirely absent from others in the same locality. 



The size, shape, and structure of their cones also distinguish the 

 two forms (fig. 2). The cone of the Rocky Mountain fir is smaller, 

 fewer-scaled, and more evenly conical than that of the coast fir. Its 

 bracts project more, and are strikingly reflexed, often standing 

 out at right angles from the cone-axis. Cones of the coast fir a.re from 

 2 J to 44 inches long and about 1 inch broad, while those of the moun- 

 tain form are rarely over 3 inches long, though they often have a 

 breadth of 1 inch. 



Though no distinction has as yet been made on the basis of the 

 minute structure of the wood, limibermen Avho have sawed both forms 

 testify to the difference between them in grain and in ease of work- 

 ing. Pacific coast lumbermen have, furthermore, always divided the 

 coast form into two kinds, " red " and " yellow " firs. " Yellow " fir 

 commands a price of at least a dollar more per thousand feet, board 

 measure, than " red " fir. The difference is due mainly to rate of 

 growth. In the humid coast climate, trees in dense stands grow 

 rapidly in height, but slowly in diameter, and the fine-grained, light, 

 yellowish wood which results is " yellow " fir. In more open stands, 

 with more light, diameter growth is faster, and the wider rings con- 

 5S39S— Cir. 150—09 2 



