116 FOREST TREES OF THE PACIFIC SLOPE. 



and transpiration ; therefore in regions with such conditions the tree confines itself 

 mainly to cooler, sheltered sites. 



Reproduction. — Moderately prolific seeder ; best in open stands. Seed of rather low 

 rate of germination and with only transient vitality. Seeding habits not fully deter- 

 mined. Cones produced mainly at irregular intervals (two to three years). Occasionally 

 few cones borne by trees about 20 years old (in open), production increasing to old age. 

 Under favorable conditions some seed germinates soon after it is shed and seedlings may 

 become established before cold weather. Moderately humous and shaded soils most 

 favorable to germination, but with sufficient moisture and light, seeds sprout and seed- 

 lings thrive in humus and in mineral soils. Seedlings come up both in open and in shade. 



White Fir. 



Abies concolor (Gord.) Parry. 



DISTINGUISHING CHARACTERISTICS. 



White fir, a massive tree, is fitly and widely called by this name from the ashy 

 hue of its bark. All of its other common names refer to its silvery or whitish 

 appearance. It grows to its largest size in the Pacific region, where it is fre- 

 quently from 140 to 180 feet and, occasionally, over 200 feet high, with a 

 diameter of from 40 to 60 inches, rare trees being from 5 to 6 feet through. In 

 its Rocky Mountain range k is much smaller — from 80 to 100 feet high, or rarely 

 more, and from 20 to 30 inches in diameter. The massive trunks are conspicu- 

 ously rough, with great deep, wide furrows and ridges in the ash-gray bark, 

 which is from 4 to 6* inches thick, and very hard and horny. The smooth, 

 unbroken bark of the upper stem, and of young trees, is grayish, with a brown- 

 ish tinge. The dense crown of heavily foliaged. short branches is an irregular, 

 round-topped cone, extending to the ground on trees in open stands, and in dense 

 stands covering only a third or a half of the upper stem. The trunks are straight 

 and taper very gradually. Young trees have beautifully symmetrical, sharp 

 crowns down to the ground, the lower limbs standing out horizontally and those 

 above slanting upward. On old trees the lower crown branches droop conspicu- 

 ously, as do also those of the middle crown; while branches above this remain 

 upright. In old age the more rapid growth of upper side branches than of the 

 loader forms a rounded top. Young foliage of the year is yellow-green, with a 

 bluish cast, but later it turns to a pale yellow green, with a whitish tinge. The 

 leaves are flat, straight, and full and plump on the upper side, 'blunt or 

 pointed — usually not prickly, but sometimes prickly on the lower crown 

 branches of old trees. They stand out distinctly from two sides of the lower 

 branches by a twist in their base (fig. 43) ; but very commonly the lower 

 branches of young trees have their leaves curved and standing erect, somewhat 

 in two lines, from the upper sides of the twigs. Leaves of the upper crown, 

 ospocially on the topmost branches, are strongly curved or sickle-shaped, and 

 appear to grow from the upper sides of the branchlets (fig. 44). These leaves 

 and those on leaders are sharp-pointed. Lower branch leaA'es are usually 

 longer (1J to 3 inches long) than those of the upper branches, which are com- 

 monly about 1 to 1J inches long. There is very great variation in the length 

 form, and thickness of leaves of this fir in different parts of its wide 

 range. The changes in form from horizontally flattened leaves to vertically 

 flattened ones, or to those resembling a sickle-blade, are curious; they are unex- 

 plained, except perhaps by the fact that the latter form is best adapted to 

 the dry climate in which it most often occurs. Some authors hold that Rocky 

 Mountain trees bear longer leaves, and more commonly pointed ones, than do 

 trees of the Pacific forests. The writer has seen trees in the latter region with 

 quite as long leaves, while long blunt leaves are not infrequent on trees of the 



