148 FOREST TREES OF THE PACIFIC SLOPE. 



LIBOCEDRTJS. 



Trees of this group are characterized by their conical trunks, their thick 

 bark, and the very strong but pleasant odor of their light, soft, straight- 

 grained, durable wood. Tbe small scale-like, pointed leaves (of adults) are 

 evergreen ; those of each season's growth remain on the tree four or five years. 

 They overlap each other closely ; much flattened on short side branchlets. but 

 rounded on the larger main stems. The branchlets are arranged in one plane, 

 forming a flat spray. Seedling leaves are scale-like, sharp-pointed, and spread- 

 ing. All of the leaves are characteristically arranged in pairs, each pair placed 

 on the branch at right angles to the preceding pair. The leaves are also distin- 

 guished by their long bases, which extend down the branch. Male and female 

 flowers at the end of branchlets formed the preceding year are borne either on 

 different twigs of the same branch (native Libocedrus) or on different trees. 

 The small cones, which mature in one season and hang down from the branches, 

 are composed of 3 pairs of scales (practically of only 2) — one very short pair 

 and one, the largest pair, forming most of the cone's body and inclosing 1 or 2 

 winged seeds on each of its scales: the third pair is formed into a central flat, 

 thick, woody wall, upon each face of which the seed-bearing scales clasp. The 

 seeds are shed in early autumn, their light wings adapting them well for wide 

 dissemination. After shedding their seeds the cones remain on the trees at least 

 until the succeeding summer. All of the trees of this group are rather large, 

 important forest trees, and their durable woods are commercially valuable. They 

 are nearly all long-lived. One species only, confined to our Pacific 1'egion, inhab- 

 its the United States. Two very important species grow in western South 

 America. The group is further interesting from the fact that in geologic times 

 species related to those now living existed in Greenland and portions of Europe. 



Incense Cedar. 

 IAbocedrus decurrens Torrey. 



DISTINGUISHING CHARACTERISTICS. 



The striking characteristics of old incense cedar trees are their rapidly 

 tapering trunks with widely buttressed bases and cinnamon-brown, deeply fur- 

 rowed, and ridged bark.' The bark is from 2 to 3 or more inches thick at the 

 base of the trunks: higher up it is scarcely more than an inch thick. Young 

 trees have thin, smooth, slightly scaly, clear, reddish cinnamon colored bark. 

 Height, from 75 to 00 or sometimes 100 or 110 feet (very rarely more), and 

 from 30 to 50 inches in diameter; exceptionally large trees are from 5 to G 

 feet in diameter. The crowns of large trees are very open and irregular, con- 

 sisting of a few scattered branches on the upper third of the stem, and 

 several large, leader-like top branches, all with dense tufts of light yellow- 

 green foliage. Young trees, up to about 12 inches in diameter, carry a narrow, 

 open, columnar, pointed crown, reaching to the ground. At the bottom of the 

 crown the branches are slender and curve down and up at their ends ; higher 

 up they gradually swing upward more and more toward the narrow pointed top. 

 Short, flat, drooping sprays of foliage terminate the branches. A notable fea- 

 ture of the branches is that they shed numerous short side twigs, which die in 

 about their second year, as the main divisions of the branch enlarge. (This is 

 the case also with other cedars, particularly Thujas.) The scale-like leaves 

 (fig. 58) have been sufficiently defined under the characteristics of the genus, 

 as have also the cones (fig. 58). The flowers, male and female, are borne on the 

 ends of separate twigs of the same branch and open in midwinter. The cones 



