550 



Perigynous, 130* 



Perigyny, 395 



Peronosporales, 244-247* 



Petal, 123, 377* 



Petiole, 88 



Peziza, 251* 



Phseophycese, 205-213* 



Phanerogams, 354 



Phloem, 312* 



Phosphates, 29 



Phosphorus, 28, 29 



Photosynthesis, 107-115, 162, 172 



Phycomycetes, 239-247* 



Phylloxera, 247 



Physcia, Plate V 



Physiology, plant, definition of, 2 



Phytophthora, 246* 



Pine forests, 457*, 490, 529* 



Pine needle, 364, 365* 



Pine seedling, 18* 



Pine stem, 366-369* 



Pinnae, leaflets of a pinnately com- 

 pound leaf, 92* 



Pinnate, 89, 90*, 91*, 92* 



Pinnules, leaflets of a pinnately twice 

 compound leaf, 98* 



Pistil, 123-126*, 128*, 358, 377* 



Pistillate flower, 124* 



Pitcher plant, 409* 



Pith, 58-61*, 65*, 67*, 72, 366* 



Placenta, 129*, 130 



Plains region, 490, 492, 493 



Plankton, 195 



Plant breeding, 600-513* 



Plant cell, 159-161* 



Plant communities, 447 



Plant ecology, definition of, 2, 3 



Plant evolution up to pteridophytes, 

 306 



Plant formations, 474-480* 



Plant geography, 481-495* 



Plant geography, definition of, 2, 3 



Plant geography of United States, 

 489-495* 



Plant fertilizers, 524 



Plant fibers, 526-529* 



Plant food for domestic animals, 523, 

 524 



Plant food for human use, 514-522* 



Plant fuel, 534 



Plant grains, 514-516* 



Plant manufactures, 524, 525* 



Plant medicines, 522, 623 



Plant physiology, definition of, 2 



Plant products, 514-535* 



Plant societies, 447 



Plant successions, 454-458* 



Plant timber, 529-533* 



Plants, destruction of, by animals, 



413 

 Plants, groups of, in relation to water 



economy, 459 



Plants of uneatable texture, 415 

 Plants, ornamental, 534, 535 

 Plasmolysis, 38* 

 Plasmopara, 247 

 Platycerium, 309*, 310, 472* 

 Pleurococcus, 179-180* 

 Pleurotus, Plate VI 

 Plowrightia, 252* 

 Plumule, 5*, 6, 7*, 14, 15 

 Plurilocular sporangia, 206*, 207 

 Pod, 441-443* 

 Poisonous plants, 419 

 Poisonous roots, 25 

 Poisonous seeds, 11, 419 

 Polar nuclei, 383* 

 Pollarded trees, 87 

 Pollen, 127, 141*, 358 

 Pollen-carrying apparatus, 422*, 423 

 Pollen chamber, 362*, 371 

 Pollen, discharge of, 140 

 Pollen grain, germination of, 142, 



143* 

 Pollen grains, number of, per ovule, 



144, 145 

 Pollen, protection of, 426, 427, 434*, 



435 



Pollen sac, 378*, 379, 380 

 Pollen tubes, 142*, 143* 

 Pollination, 142*, 144*, 145, 357, 



371, 420-434* 



Pollution of water supply, 171, 178 

 Polyadelphous, 127 

 Polypetalous, 126 

 Polysepalous, 126 

 Poiysiphonia, 218, 219* 

 Polytrichum, 296* 

 Pome, 148 



Pond scum, 193-195* 

 Pond zonation, 476-478* 

 Pore fungi, 264, 265* 

 Porella, 286*, 287* 

 Position of buds, 82*, 83, 87* 

 Postelsia, 209* 

 Potassium, 28, 29 

 Potato blight, or rot, 246* 

 Potato tuber, 52*, 53, 78, 79 

 Prairies, 492, 493 

 Prickle, 416*, 417* 



