. Bulletin (Pennsylvania Department of Forestry), no. 11. Forests and forestry. come furrowed later, while many other species become rough early in life. The manner in which the bark cracks open or peels off af- fords a ready means of identification for many of our trees. The exfoliation of the bark is rather constant for each species. In some species like the Yellow Birch and Paper Birch it peels off in thin film-like papery layers. In the Shag-bark Hickory it is shaggy; in many species like the Pines and Spruces it is scaly; while in others like the White Cedar it is shreddy. Many species ha
. Bulletin (Pennsylvania Department of Forestry), no. 11. Forests and forestry. come furrowed later, while many other species become rough early in life. The manner in which the bark cracks open or peels off af- fords a ready means of identification for many of our trees. The exfoliation of the bark is rather constant for each species. In some species like the Yellow Birch and Paper Birch it peels off in thin film-like papery layers. In the Shag-bark Hickory it is shaggy; in many species like the Pines and Spruces it is scaly; while in others like the White Cedar it is shreddy. Many species have furrowed bark. The furrows run usually in a longitudinal direction but may run transversely. The furrows or fissures separate ridges. These vary with the species. The fissures may be short or long, close or distant, narrow or wide, longitudinal, transverse, or diagonal. The ridges may be pointed or broad, high or low, smooth or scaly. The bark may be broken up into small square or rectangular blocks as in the Black Gum. This form of bark is often spoken of as "alli- gator ; See Figures 44-103 for bark of most of our important native trees. The bark may be of considerable technical value. Hemlock and some species of Oak and Spruce have bark which is rich in tannin. The bark of these species is used extensively in the leather industry. The bark of a European species of Oak is highly prized on account of the large quantity of cork which it produces. The inner bark of some species yields dyeing material while that of others is used in the manufacture of fibre cloth. Formerly the bark of the Paper Birch was used in the construction of canoes. 3. Twigs : Twigs are the terminal parts of branches. The term twig usually refers to that portion of the terminal part of the branch which grew in the last season. Those portions of the branch which began their growth a few seasons ago are usually spoken of as older twigs or branchlets. The twigs have their origin in the veget
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectforests, bookyear1901
