INDEX 



807 



Petal, 336, 353 

 Petiole, 13, 18, 72 

 Petrified logs, 721 

 Phaeophyceae, 608, 628-633 

 Phenotype, 463 



Phloem, 71, 72, 223, 264, 266, 282, 303; 

 fibers, 264, 283; parenchyma, 283; pri- 

 mary, 304; rays, 264, 284; secondary, 

 304 



Phosphates, 45, 143, 539 



Phosphorus, 142, 177, 328 



Photoperiod, 340 



Photoperiodism, 340 



Photosynthesis, 109-114, 315; and chloro- 

 plasts, 122; and CO„ concentration. 

 126, 127; and C0„-0„ ratio, 110; and 

 epidermis, 120; and evergreens, 123; 

 and leaves, 120; and light intensity, 

 116, 117, 126; and light rays, 116; and 

 mesophyll, 120; and plant structures, 

 118; and respiration, 152, 154, 163; 

 and temperature, 127, 163; and water. 

 118, 120; chemical equation of, 109; 

 factors involved in, 112, 115; inter- 

 mediate compounds, 124; rates of, 

 115-128 



Phycocyanin, 608 



Phycoerythrin. 608 



Phycomycetes, 552 



Phylloxera, 420. 578 



Physiological drought, 205, 210 



Pickleweed, 211 



Pigments, 27-32, 171, 511 



Pihilarin, 667 



Pine, Austrian, 683; cones. 683. 684 

 eastern white. 758; embryo, 686 

 "endosperm," 685; lodgepolc, 787 

 long-leaved, 761; needle, 87, 682 

 pinon, 788; seed. 686; short-leaved 

 760; western white, 784; western vel 

 low, 782 



Pineapple, 367, 699: familv. 699 



Pinesap, 30, 504 



Pistil, 12, 354, 373, 376 



Pistillate cones, 683; flowers. 359 



Pitcher plant. 92 



Pith, 13, 24, 223. 265, 266. 279 



Placenta, 336 



Plankton, 596. 597, 602, 611 



Plant associations. 752; breeding. 431; 

 communities. 40-49, 236. 238. 643: 



composition. 177; curvatures. 209, 213, 

 215; diseases, 567-585; foods, 101-107; 

 formations, 743-792; introductions, 

 431; names, 18, 25; organs, 10-17; 

 parts, 10-17; populations, 42, 425, 499, 

 596; restorations, 725, 728, 729,/ 730; 

 science, 1-9; selection, 432; sucg^ssion, 

 41, 46, 737, 753 

 Plants, and animals, 1, 2. 5, 45, 604, 

 610; day-neutral, 344; difficulty in 

 definition of, 3; distribution of, 165, 

 719-738, 740-795; domesticated, 423. 

 500; long-day, 340, 341, 348; non- 

 green. 504-514; of the past, 719-738; 

 origin of. 423-436; pioneer, 46; sea- 

 sonal aspects of. 26-38; short-day, 341. 

 342, 348; uses of, 1-3; varieties of. 131 



Plasmodium, 562 



Plasmolysis, 205 



Plastid, 60, 63, 65. 129; inheritance, 444 



Pleistocene period, 723 



Pleiirococciis, 565, 613, 614, 636 



Pliocene period, 723 



Plumule, 10, 11, 367 



Poaceae, 693 



Pollarding, 251 



Pollen, 372, .383, .385; fossil, 736, 737; 

 sac, 372; tube, 374, 376 



Pollination, 374, 431, 684; close, 431; 

 cross, 381, 440; insect, 384; self, .381 



Polyembryony. 380 



Polyploidy, 476-478. 480 



Polysaccharides, 135. 628 



Polystichxini, 656 



Polytridnim, 643, 644 



Pome, 356, 363, 366 



Ponds. 590 



Populations, changes in plant. 43, 425 



Porella, 652. 653 



Postelsia, 629, 630 



Potassium, 45, 177, 328 



Potato family, 715; flowers. 716; sprouts. 

 53; tubers, 189, 409. 410 



Pottery, 427 



Poverty grass, 45 



Prairie, 764 



Pre-Cambrian floras, 727 



Preconditioning. 346, 347 



Prickle, 258 



Primordium, 68 (see also plant organs) 



Pronuba moth. 385 



