294 



A(}H()X()MY 



( )vules, 79 



Oxygen, characteristics of, 8 



Palisade tissue, 73 



Parasites, 230 ; wound, 238 



Parenchyma, 73 



Parthenogenesis, 269 



Peat, 29 



Pebbles, 31 



Perennials, 88 ; arrangement of, 206 ; 

 herbaceous, 89 ; use of herbaceous, 

 206 ; woody, 89 



Petals, 79 



Petiole, 71 



Phloem, 66 



Phosphorus, characteristics of, 9 ; 

 source of, 105 ; use of, to plant, 99 



Photosynthesis, 75 ; contrasted with 

 respiration, 76 



Pith cells, 65 



Plan of the flower, 83 



Plant breeding, advantages of, 258 ; 

 basis for, 259 ; results of, 267 



Plant diseases, blights, 234 ; how 

 caused, 230 ; leaf spots, 234 ; meth- 

 ods of preventing, 243; mildews, 

 235 ; molds, 235 ; number of, 232 ; 

 rots, 233 ; rusts, 237 ; smuts, 237 ; 

 variety, 239 ; wilts, 233 



Plant food, distribution of, 76 ; for- 

 mation of, 75 ; source of the ele- 

 ments in, 75, 97, 105 ; storage of, 

 76 



Plant growth, limiting factors in, 111, 

 114 



Plant hairs, 118 



Plant houses, 158 ; how heated, 159 



Plants, antagonisms of, 103 ; cellular 

 structure of, 57 ; 'edible parts of, 

 278 ; effects of cold on, 117 ; effects 

 of overwatering, 124 ; life cycle of, 

 87 ; regions of, 57 ; relationships of, 

 90 ; rest period of, 89 ; time to 

 water, 124 ; variations in, 259 



Plowing, 150 



Pollarding, 225 



Pollen, 79 ; of wind-pollinated flow- 

 ers, 82 



Pollination, 79 ; agencies for, 80 ; 

 organs necessary for, 80 ; second- 

 ary effects of, 83 



Potash plants, 99 



Potassium, characteristics of, 5 ; 

 sources of, 105 ; use of, to plants, 

 99 



Practical exercises, 10, 24, 36, 53, 92, 

 100, 112, 128, 147, 156, 163, 180, 

 196, 214, 228r 243, 257, 21,'t, 276, 

 283 



Precipitation, 44 



Pricking out, 141 



Propagation, artificial, 183; by cut- 

 tings, 184-, forms designed for, 

 182 ; natural methods of, 181 



Propagation, forms for: bulblet, 183 ; 

 cormel, 183 ; offset, 182 ; rootstock, 

 182 ; runner, 182 ; stolon, 182 ; 

 sucker, 182 ; tuber, 182 



Pruning, implements for, 217 ; 

 methods of, 217, 218; plants that 

 do not need, 218; purpose of, 215 ; 

 season for, 216, 220 ; special crops, 

 219 



Rainfall, annual, in United States, 46 ; 

 distribution of, in United States, 

 44, 45 ; distribution of, in world, 45 



Receptacle, 79 



Respiration in plants, 76 



Rest period of plants, 89 



Retarding plants, 157 



Ribbon bedding, 208 



Rocks, aqueous, 21 ; igneous, 21 ; 

 metamorphic, 21 ; sedimentary, 21 ; 

 table of, 22 



Roguing, 268 



Root crops, 279 



Root grafting, 194 



Root hairs, absorption by, 63 ; ad- 

 vantage of, 62 ; structure of, 62 



Root pressure, 97 



Root pruning, 226 



Root system, axial, 60; inaxial, 60; 

 of corn, 58, 59 



Roots, central cylinder in, 60 ; cortex 

 of, 60 ; ducts in, 60 ; epidermis of, 

 60 ; extent of, 59 ; multiple primary, 

 60 ; structure of, 59, 60 



Rose, green, 64 



Rotation of crops, character of, 155 ; 

 reason for, 155 



Run-off, 47 



Sand, amount of pore space in, 41 ; 



characteristics of, 31, 33; run-off 



of water on, 47 

 Saprophytes, 230 

 Scientific names, 91 

 Seed packets, how to close, 146 ; how 



to make, 146 



