_b._ Wood of medium weight and hardness, usually light colored. SILVER MAPLE. [Illustration: Fig. 137. Wood of Maple.] Red maple is not always safely distinguished from soft maple. In box elder the pores are finer and more numerous than in soft maple. The various species of elm may be distinguished as follows: 1. Pores of spring wood form a broad band of several rows; easy splitting, dark brown heart ............................RED ELM. 2. Pores of spring wood usually in a single row, or nearly so. _a._ Pores of spring wood large, conspicuously so WHITE ELM. _b._ Pores of spring wood small to minute. _a.'_ Lines of pores in summer wood fine, not as wide as the intermediate spaces, giving rise to very compact grain ROCK ELM. _b.'_ Lines of pores broad, commonly as wide as the intermediate spaces .........................WINGED ELM. _c._ Pores in spring wood indistinct, and therefore hardly a ring-porous wood .................................CEDAR ELM. [Illustration: Fig. 138. Wood of Elm. _a_ red elm; _b_, white elm; _c_, winged elm.] [Illustration: Fig. 139. Walnut. _p.r._, pith rays; _c.l._, concentric lines; _v_, vessels or pores; _su. w._, summer wood; _sp. w._, spring wood.] [Illustration: Fig. 140. Wood of Cherry.] INDEX. _Abies grandis_, 96. _Acer dasycarpum_, 172. _Acer macrophyllum_, 170. _Acer rubrum_, 174. _Acer saccharinum_, 172. _Acer saccharum_, 176. _Agaricus melleus_, 236. _Agarics_, 234, 236. Alburnum, 17. Ambrosia beetles, 242. Angiosperms, 9. Animal enemies, 239. Arborvitae, Giant, 104. Ash, 182-191, 296. Ash, Black, 182, 298. Ash, Blue, 186. Ash, Hoop, 182. Ash, Oregon, 184. Ash, Red, 188, 298. Ash, White, 25, 190, 298. Bamboo, 10, 11. Bark, 10, 13, 14. Bark borers, 243. Basswood, 14, 178, 301. Bast, 13, 15, 16, 20. Beech, 134, 300. Beech, Blue, 124, 300. Beech, Water, 124. Beech, Water, 162. Bees, carpenter, 246. Beetles, 241-246. _Betula lenta_, 130. _Betula lutea_, 132. _Betula nigra_, 128. _Betula papyrifera_, 126. Big Tree, 98, 208, 209, 220. Birch, Black, 130. Birch, Canoe, 126. Birch, Cherry, 130. Birch, Gray, 132. Birch, Mahogany, 130. Birch, Paper, 126. Birch, Red, 128. Birch, River, 128. Birch, Sweet, 130. Birch, White, 126. Birch, Yellow, 132. Bird's eye maple, 36. Bluing, 234. Bole, 211, 218. Borers, 243-246. Bowing, 47. Branches, 37, 218, 226, 286. Brittleness, 53. Broad-leaved trees. See Trees, Broad-leaved. Browsing, 240. Buckeye, 301. Bud, 14, 16, 36. Buds, Adventitious, 36, 37. Bullnut, 118. _Buprestid_, 243. Burl, 35. Butternut, 144, 300. Button Ball, 162. Buttonwood, 162. Calico poplar, 246. Cambium, 10, 13, 14, 15, 16, 22, 237. Canopy, 204, 211, 212.