408 
Pickerel-weed, 186 
Pigment, 94, 95, 97 
Pig-weed, 354 
Pinacee, 270 
Pine, 270, 272, 283 
Pineapple, 326, 329 
Pine, archegonia of, 292, 293 
Pine-drops, 269 
Pine-family, 270 
Pine, Jersey, 275 
Pine, pitch, 275, 283 
Pine, pollen of, 287, 293 
Pine-sap, 99 
Pine, scrub, 275 
Pine, white, 281 
Pines, 299 
vitality of, 283 
Pinks, 139 
Pink family, 222, 225 
Pistil, 22, 29 
Pistillate flower, 77 
Pith, 102, 130, 132 
Plantago lanceolata, 359 
Plantago major, 357 
Plantain, 128, 357 
Plantain, flowers of, 359, 360 
Plumed fruits, 349 
Plum-leaves, 56 
Poison-ivy, 235 
Pollen, 22, 28 
Pollen-carriers, 30 
Pollen-grain, 24, 27, 28 
Pollen-grains of the 
suckle, 204 
Pollen-tube, 26, 27 
honey- 
Pollen of ‘‘ water-fertilized’”’ 
flowers, 30, 31 
Pollen of ‘‘ wind-fertilized"’ 
flowers, 30, 31 
Pollen of oat blossoms, 165 
Pollen of rushes, 185 
Pollen, waste of, 28, 31 
Polygamous flowers, 73 
Pond-weeds, 31 
Poplar, 31, 50, 51, 52, 54, 61, 73 
Poplars, 49, 51, 73, 75. 93 
white, 53 
Populus alba, 50 
Potato, starch-grains of, 103 
Potash, 369 
Prickles, 110, 319, 325 
Index 
Prickles, how they differ from 
thorns, 325, 326 
Prickly-ash, 74 
Primroses, diurnal, 227 
Primroses, evening, 227, 229 
Problems of nature, 345 
Procambium, 130 
Prof. Gray quoted, 83 
Prof. von Sachs quoted, 368, 369 
Proteids, 91 
Protoplasm, go, gI, 100, 105 
Prothalli, 251 
of adders’ tongues, 252 
of club-mosses, 252 
of ferns, 252 
of gymnosperms, 292 
of horse-tails, 252 
of selaginellas, 292 
Prothallus, 250, 258, 259, 298 
Rag-weed, 39. 350, 352 
Rape, 119 
Ray flowers, 352 
Red campion, 225 
Red cedars, 288, 296, 298 
Red maple, 54, 74 
Red maples, 75 
Red-top, 169 
Reed, 175 
Reeds, 175, 176 
Reptiles, age of, 285 
Resin, 282, 386 
Reversion to type, 136 
Revolving of vine-tips, 236, 237 
Rib-wort, 357 
Ripple-grass, 359 
Rice, 118, 151 
blossom of, 172 
wild, 175 
Richter (Jean Paul) quoted, 230 
Rings in timber, 135 
Rogue type, 98, 99 
Rolled fronds of ferns, 260 
Root-climbers, 234, 235 
Root-hairs, 250, 3g0 
Root-stocks, of ferns, 260 
Root-stocks, of grasses, 152, 153 
Root-tips, 390 
Rose, 116, 117, 123, 128 
Roses, 136 
Rose-bush, 131 
