Pyrenoid, 25, 31. _Pyrenomycetes_, 76. _Pyrola_, _-aceæ_, 210. Quince, 170. Quill-wort, 125, 126; Fig. 74. Raceme, 174. Radial fibro-vascular bundles, 138, 176. Radish, 192. _Ranunculus_, _-aceæ_. See "Buttercup." Raspberry, 207. Ray-flower, 223. Receptacle, 167, 207, 223. Receptive spot, 106. Red algæ, 21, 49, 52, 53; Figs. 29-31. Red-bud, 209; Fig. 115. Red cedar, 79, 131, 141; Fig. 78. Red-wood, 142. Reference-books, 235-236. _Reseda_, _-aceæ_. See "Mignonette." Resin, 130. Resin-duct, 130, 135, 137. Resting-spore, 28, 32, 37, 57. Rheumatism-root. See "Twin-leaf." _Rhexia_, 206. _Rhizocarpeæ_. See "Water-fern." Rhizoid. See "Root-hair." Rhizome. See "Root-stock." _Rhododendron_, 210; Fig. 116. _Rhodophyceæ_. See "Red algæ." _Rhodoraceæ_, 211. _Rhœadinæ_, 190. _Rhus_. See "Sumach." _cotinus_. See "Smoke-tree." _toxicodendron_. See "Poison-ivy." _venenata_. See "Poison-dogwood." _Ribes_, _-ieæ_, 203; Fig. 111. _Ricciaceæ_, 91; Fig. 57. _Richardia_. See "Calla." _Ricinus_. See "Castor-bean." Ringless-fern, 116. Rock-rose, 195. Rock-weed. See "_Fucus_." Root, 102, 104, 114, 173. Root-cap, 115, 175. Root-hair, 38, 87, 91, 96, 104, 135. Root-stock, 154, 172. _Rosa_, _-aceæ_. See "Rose." Rose, 181, 206; Fig. 114. _Rosifloræ_, 206. _Rubiaceæ_, 223. Rush, 154, 225; Fig. 83. Rust, white. See "_Cystopus_." red. See "_Uredineæ_." black. See "_Uredineæ_." _Sabal_. See "Palmetto." _Sabbatia_. See "Centaury." _Saccharomycetes_. See "Yeast." Sac fungi. See "_Ascomycetes_." Safranine, 233. Sage, 215; Fig. 120. _Salicineæ_, 183. _Salix_. See "Willow." _Salvinia_, 118. _Sambucus_. See "Elder." _Sanguinaria_. See "Blood-root." _Sapindaceæ_, 199. _Saprolegnia_, _-aceæ_, 60-62; Fig. 36. zoöspores, 62. resting spores, 62. antheridium, 62. _Sargassum_, 48; Fig. 28. _Sarracenia_, _-aceæ_. See "Pitcher-plant." Sassafras, 188. _Saururus_. See "Lizard-tail." Saxifrage, 202. _Saxifraginæ_, 202. _Scabiosa_. See "Scabious." Scabious, 224. Scalariform, 110. Scale-leaves, 170. _Scenedesmus_, 24; Fig. 11. _Schizomycetes_. See "_Bacteria_." Schizophytes, 12, 14. Schlerenchyma. See "Stony tissue." _Schrankia_. See "Sensitive-brier." _Scilla_, 151. _Scirpus_. See "Bulrush." _Scitamineæ_, 153, 162. Scotch pine, 129-140; Figs. 75-77. stems and branches, 129. leaves, 129, 130. gross anatomy of stem, 130. growth-rings, 130. roots, 131. sporangia, 131. cones, 132. macrospores and prothallium, 133. ripe cone and seeds, 133. germination, 134. young plant, 134. histology of leaf, 135. of stem, 136-138. of root, 138. microsporangium and pollen spores, 138, 139. archegonium, 140. fertilization, 140. Scouring-rush, 122. _Scrophularia_, _-ineæ_. See "Figwort." Sea-lettuce, 26; Fig. 15. Sea-rosemary, 212. Sea-weed (brown). See "Brown algæ." (red). See "Red algæ." Sedge, 161; Fig. 87. _Sedum_. See "Stonecrop." Seed, 128, 133, 145, 150.