366 
Russian thistle, 167, 168 
Rusts, *253-256 
Sac fungi, *242-247 
Saccharomycetes, 261 
Sachs, Julius, 56* 
Sap, 24 
Saprophytes, 48, *50-52, 234 
Saprophytic bacteria, 203, 204 
Saprophytism, 48, 51, 52 
Sapwood, 66 
Sargasso Sea, 231 
Sargassum, 231, 260 
Sassafras wood, section of, 110* 
Schizomycetes, 260 
Scion, 92* 
Sclerenchyma, 285* 
Sclerotinia, 242*, 261 
Scouring rush, 278*, 279 
Scramblers, 74 
Scutellum, 16 
Seed, 15-18, *#157-171, 303 
Seed coats, 158*, 160 
Seed distribution, *166-171 
Seed leaf, 18*, 158* 
Seed plants, *282-307 
Seed testing, 163 
Seedlings, 18*, *159-165 
Seedlings, mutilated, growth of, 165* 
Seedlings, types of, 18*, 159*, 160* 
Selection by plant breeder, 175, 177, 
*178-186, 191 
Self-pollination, 139, *140-142 
Self-pruning, 77, 78 
Sepal, 14*, 126* 
Sequoia, 24, 287*, 294 
Sexual reproduction in angiosperms, 
*135-137, *298-803 
Sexual spore, 225 
Shepherd’s-purse, ovule and embryo, 
803* 
Shoot, 56 
Sieve tubes, 20*, 43, 63* 
Simple pistil, 131 
Sisal, 318 
Smuts, *251-253 
Soft bast. See sieve tubes 
Soil, 26, 39, *3819-327 
Soil, relation of roots to, 26, 27, 324* 
Soil bacteria, #204-207, 323 
Soil fertility, 323-325 
Sorrel, 334* 
Sorus, 273 
Spanish moss, 49, 50* 
Species, 194-196 
INTRODUCTION TO BOTANY 
Sperm, 228, 265*, 275* 
Spermatophytes, 196, 306 
Spermatophytes, evolution of plants, 
806 
Sphagnum, 267*, 268 
Spirogyra, 228, 224*, 225, 239, 260 
Spongy parenchyma of leaf, 36* 
Sporangium, 272*-274 
Spore, 203, 224*, 227%, 228% 
Sporidia, 225* 
Sporophyll, 278*, 290, 291*, 299 
Sporophyte, 266 
Sport, 173 
Spraying, 240*, 241, 318, 319 
Sprengel, 138 
Spruce, 293* 
Spur, fruit, 98, 99% 
Squash seed, section of, 158* 
Stamen, 14*, 15, *125-130 
Staminate flower, 127* 
Starch, 7, 14, 17, 40*, 48, 348, 344 
Starch-making, 38-40, 348, 344 
Stem, dicotyledonous, minute struc- 
ture of, *62-65 
Stem, functions of, 12, 56-60 
Stem, monocotyledonous, 68*, 69 
Stem, rate of growth of, 60, 61, 288 
Stem, structure of, 11*, 12*, *62-68 
Stems, climbing, 74, 75 
Stems, underground, *86-88 
Sterilization, 194, 195 
Stiffening, mechanics for, *62-65 
Stigma, 131*, 300, 301* 
Stimulus, 22 
Stipe, 257 
Stipules, 69*, 101 
Stock, 92* 
Stolon, 89*, 90 
Stomata, 35*, 36* 
Stonewort, 229% 
Storage of food in root, 44%, 45 
Storage of food in seed, 17*, 165. 
166 
Storage of food in stem, *87-89 
Strengthening tissue, 11, 64*, 65 
Struggle for existence, *167-172 
Style, 300 
Submerged leaves, 79* 
Sugar, 7, 38, *309-312 
Sugar, formed during germination, 
165, 166 
Sugar beet, 312 
Sugar cane, 311*, 312 
Sugar maple, 309, 310* 
Sugar pine, 295* 
