INDEX 



543 



Self-pollination, 120, 121* 



Self-pruning, 66, 93-95 



Sepal, 20*, 105* 



Sequoia, 304*, 311*, 313* 



Sex, origin of, 197 



Sexual reproduction in angiosperms, 



*1 15-1 18 

 Sexual spore, 194 

 Shade plants, 489-492 

 Sheplierd's-purse, ovule and embryo, 



327* 

 Shoot, 39 



Short-stemnaed plants, 58* 

 Sieve tubes, 45*, 80 

 Simple pistil, 105*, 112 

 Slime molds, 224*, 225 

 Smilax. See Wyrsiphyllum 

 SmJlax, 62* 

 Smuts, *240-242, 454 

 Snail pollination, 130 

 Snapdragon, flowers of, 126* 

 Soft bast (sieve tubes), 45*, 80 

 Soil, 434-451 



Soil bacteria, 374-378, 449 

 Soil fertility, 447-451 

 Solomon's seal, rootstock of, 73* 

 Solomon's seal, leaf of, 336* 

 Sorrel, 467* 

 Sorus, 280 



Spanish moss, 381, 382, 489* 

 Spanish needles, fruits of, 146* 

 Species, 156, 158 

 Sperm, 201, 202* 219, 261*, 269*, 



283, 308, 318 

 Spermatophytes, 158 

 Spermatophytes, evolution of plants, 



380, 334 

 Sphagnum, 264*, 265 

 Spiderwort, 343* 

 Spike, 516* 

 Spiral vessel, 46* 

 Spirogyra, *191-193 

 Spongy parenchyma of leaf, 14* 

 Sporangiophore, 216 

 Sporangium, 279*, 281* 

 Spore, 190 

 Sporidia, 245 

 Sporophyll, 290 

 Sporophyte, 263-265 

 Spraying, 222, 453* 454, 455 

 Spruce, Douglas, 315* 

 Spruce trees. 6* 257/312 

 Spur, fruit, 04*. 95, 96 

 Spurge family, 356*, 357* 

 Squash seed, section of, 136* 



Stamen, 20*, 104*, 105*, 110*, 111*, 



307, 323 

 Staminate flower, 106*, 108* 

 Starch, 15-17, 35, 77-80, 82, 138, 145 

 Starch in leaves, 78, 79 

 Starch-making, 16 

 Stem, 11* 12*, *39-55, 74-77, *80- 



103 

 Stem, dicotyledonous, minute struc- 

 ture of, 44, 45*, 46*, 47*, 48*, 411* 

 Stem, early history of, 52*, 142*, 143* 

 Stem, functions of, 39-42 

 Stem, monocotyledonous, 53, 54*, 55 

 Stem, rate of growth of, 44 

 Stem, structure of, 11*, 12*, *44-54 

 Stemless plants, 58* 

 Stems, climbing, *60-64 

 Stems, storage of food in, 77 

 Stems, twining, 60*, 61 

 Stems, underground, 72*, 73*, 74* 

 Sterilization, 169 

 Stiffening, mechanics for, 48, 49* 

 Stigma, 112*, 324 

 Stimulation, responses to, 389 

 Stipe, 249 

 Stipules, 91* 



Stomata, 13«, 14, 303*, 483* 

 Stone fruits, 461, 462 

 Stonecrop, flower of, 105* 

 St(jnewort, 205, 207* 

 Storage of food in root, 33, 34*, 35 

 Storage of food in the seed, *137-139 

 Storage of food in the stem, 77 

 Strawberries, 460, 461 

 Strengthening tissue, arrangement 



of, 48, 49* 

 Strobilus, 292*, 294* 

 Struggle for existence, 148-151 

 Style,''ll2*, 324 

 Submerged leaves, 480*, 481* 

 Sugar, 15-17, 337, 424 

 Sugar, formed during germination, 



145 

 Sugar beet, light requirement of, 



493 

 Sugar-beet breeding, 424, 425 

 Sugar cane, 337, 339* 

 Sulphur, 15, 448 

 Sumach, 361 

 Summer-deciduous trees and shrubs, 



70, 486 

 Sun plants, 489, 492, 493, 494 

 Sundew, 385*, 386* 

 Sunflower stem, cross section of, 



45* 



