Rose Family, 97. Rough Oak, 153. Round-leaved Maple, 88. Rowan-tree, 103. Rue Family, 73. Rutaceæ, 73. Salicaceæ, 161. Salisburia, 201. Salix Alba, 164. amygdaloides, 163. angustata, 165. annularis, 164. Babylonica, 164. caprea, 166. cinerea, 167. cordata, 165. decipiens, 164. discolor, 166. falcata, 163. fragilis, 163. longifolia, 167. lucida, 164. myricoides, 165. nigra, 163. pentandra, 165. purpurea, 165. rigida, 165. rostrata, 166. rufescens, 165. Russelliana, 164 viridis, 164. vitellina, 164. Sapindaceæ, 81. Sapodilla Family, 118. Sapotaceæ, 118. Sassafras, 130, 131. Scarlet-fruited Thorn, 104. Scarlet Oak, 156. Sciadopitys, 191. Scotch Elm, 134. Fir, 177. Pine, 177. Scrophulariaceæ, 127. Scrub Oak, 157. Pine, 177, 178. Seaside Alder, 148. Sequoia, 192, 193. Service-berry, 107. Shad-bush, 107. Shagbark Hickory, 142. Sheep-berry, 114. Shellbark Hickory, 142. Shepherdia, 132. Shingle Oak, 158. Shining Willow, 164. Shrubby Trefoil, 74. Siberian Cornel, 111. Silver Fir, 185. Silk-tree, 96. Silverbell-tree, 121. Silver Cedar, 190. Fir, 184-187. Maple, 85. Spruce, 181. Silver-leaved Elæagnus, 132. Simarubaceæ, 76. Single Spruce, 179. Slippery Elm, 134. Sloe, 98. Smoke-tree, 91. Smooth Alder, 148. Sumac, 90. Soapberry Family, 81. Sorrel-tree, 116. Sour Gum, 112, 113. Sourwood, 116. Southern Cypress, 192. Spanish Oak, 156, 157. Speckled Alder, 147. Spice-bush, 131. Spindle-tree, 78. Spruce, Alcock's, 181. Black, 179. Double, 179. Eastern, 181. Himalayan, 181. Norway, 180. Oriental, 181. Silver, 181. Single, 179. Tiger's-tail, 180. White, 179. Spurge Family, 132. Stag-horn Sumac, 90. Sterculia, 71. Sterculiaceæ, 71. Stone-pine, 173. Storax, 120. Storax Family, 120. Striped Maple, 85. Stuartia, 69, 70. Styracaceæ, 120. Styrax, 120. Sugarberry, 136. Sugar Maple, 86. Pine, 172. Sumac, 90, 91. Summer Haw, 106. Swamp Hickory, 143. Magnolia, 63. Oak, 156. Post-oak, 154. White Oak, 154. Sweet Bay, 63. Birch, 146. Buckeye, 82. Gum, 108. Pepper-bush, 117, 118. Viburnum, 114. Sweetleaf, 122. Swiss Stone-pine, 173. Sycamore, American, 139. Sycamore-maple, 86. Symplocos, 122. Syringa, 126. Table-Mountain Pine, 177. Tacamahac, 170. Tamarack, 188. Tamariscineæ, 68. Tamarisk, 69. Tamarix, 69. Tartarian Honeysuckle, 115. Maple, 88. Taxodium, 192. Tea Family, 69. Ternstroemiaceæ, 69. Thorn, 104, 105. Thurber's Japan Magnolia, 66. Thuya, 193, 194. Thuyopsis, 193. Tiger's-tail Spruce, 180. Tilia, 72, 73. Tiliaceæ, 72. Toothache-tree, 73. Torreya, 200. Tree Hibiscus, 71.