rc- 

 508, 



Persimmon, 258 



Persistence of plants on ice-free tracts, 



162-5, 197 

 after introduction by Norse- 

 men, 181 

 Perspiration, 482 

 Peru, 226, 234, 413 

 Pes-caprae, see Ipomoca pes-caproe 

 Petal, 68, 70, 71 

 Petroleum, 130, 271 

 Peyote, 267 



pH (hydrogen-ion concentration 

 action '), 302, 303, 317, 478, 



509 



— of aquatic habitats, 319, 476, 510, 



523 



- — , cryovegetation and, 489-90 



■ — , favourable level of, 478 



— , lake-water, 319, 478 



— , variation in, 490, 523 



Phaeocystis, 517 



Phaeophyceae (Brown Algae, Brown 

 Seaweeds), 35, 36, 37, 38, 39, 481, 

 508, 530, 531, 535, 536, 538, 550 



■ — , Cambrian, 132 



— , depth relations of, 317, 522, 530-8 



— , dimensions of, 535, 537, 538 



— , dominant, 532-8 



— , drifting of, 38, 521 



— , dwarfed, 369, 508, 526 



— , girdles of, 532, 533, 535-8 



— , ice-action and, 531, 536, 537, 538 



— , industrial use of, 38, 265 



— , light and, 488, 512, 530 



— , photosynthesis of, 37 



— , rare in fresh water, 475 



— , replaced by Chlorophyceae, 532 



— , salinity and, 508, 523, 526 



— , salt-marsh forms of, 369 



— , surf-inhabiting, 525, 532, 534, 535 



— , tropical, 529 



Phalaris counriensis (Canary Grass), 115 



Phanerophyceae, 528 



Phanerophyta scandentia, 94 



Phanerophyte, 93-5, 464 



Pharmacognosy, 262 



Pharmacology, 262 



Phaseolus vulgaris (Common Bean, Gar- 

 den Bean, Kidney Bean), 233 



Phenology, 574, 576 



Phenotypic characters, 183 



Philippine Islands (forests etc. of), 423, 

 427, 429, 455, 468, 469, 470, 504 



— Islands, mangrove-swamp forest in, 



455 



Phippsia algido agg. (Frigid Phippsia), 



Plilfiiin, 364 [405 



P. alpiniiin s.l. (Alpine Timothy), 204, 



421 

 P. pratense (Common Timothy, 

 Timothy Grass), 204, 259 



INDEX 619 



Phlox, 124 



Phoenix dactylifera (Date Palm), 242, 



258, 370, 454, 458, 459 

 Phosphate content of water, Algae and, 



475, 476, 481, 488, 509, 519, 524 

 Phosphates, 319, 368, 475, 481, 519, 524 

 Photic region, in Arctic, 537 

 Photoperiodism, 79, 284, 576 

 Photosynthesis, i, 3, 32, 33, 37, 39, 47, 



51, 53. 59, 69, 130, 255, 279, 284, 



452, 473, 477, 482, 488, 496, 513, 



527 

 — , annual production by, 520 

 — , aquatic vegetation and, 317, 320, 



473, 475, 477, 493, 5", 512, Si3. 



520 

 — , bicarbonates and, 130, 497 

 — , modihed forms of, 27, 29, 39 



— respiration balance, 475, 483, 524 

 — , temperature and, 77 

 — , terrestrial andaquaticproduction by, 



520 



— under ice, 506 



Photosynthetic activity in sea, 509, 520 

 Phragmites communis agg. (Common 



Reed, Reed), 98, 461, 463, 505 

 Phycodrys, 537 

 Phyllophora, 40 

 Phylum {pi. phyla), 24, 46 

 Physiognomy, 14, 96, 463 

 Physiographic aspect, 294, 295, 296, 



322, 375, 413, 470, 544 



— barriers, 125-6 



— change, microhabitats and, 320 



— climax, 331, 411 



— condition, 8 



— effects, 294-6, 375-7 



— factors, 283, 293-6 



— vicariad, 202, 204 

 Phvsiological acti\itv, environment and, 



75-81, 482 



— antagonism, 80 



— attributes, 5 



— changes in cultivation, 216 



— drought, 337, 368-70, 458 



— functions , cardinal points of, 76-9, 

 288, 482, 485 



— make-up, 6, 9, 75-80 



— reactions, 7, 75-81 

 Physiology, plant, 4, 75 

 — , plant geography and, 75-81, 482 

 Phytogeography, see Plant geography 

 Phytometer, 321 

 Phytophthora infestans (Late-blight of 



Potato etc.), 80, 251, 279 

 Phytoplankter, 517 

 Phytoplankton {sec also Plankton), 37, 



479, 486, 488, 510, 516, 517-21, 



578 

 — , biotic factors affecting, 480-3, 487-8, 

 — , collection of, 518 [517-21 



