INDEX 



621 



Plant geography, techniques of study of, 

 • , what it is, 1-5 [571-3 



— groups, 5, 24-74 



, centres of origin of, 178, 208 



, geological history of, 128-53, 145 



— growth substances, 13, 276, 564 

 — , ideal, 12-14 



— indicators, see Indicator plants 

 like animals, 2 



— migration, 5, 97-8, 153, 155-61, 



165, 171, 323 



— nuisances, 279-81 



— pathogens, 46, 80, 250, 251-2, 265, 



305 

 , methods of control of, 251-2 



— pathology, 250 



— response, 16 



— Science Monograph, 282 

 Monographs, ii 



— sociology (phytosociology), 14-15, 92 

 Plantago (Plantain), 451, 453 



P. maritima s.l. (Sea Plantain), 369 

 Plantain, see Plantago 

 Plants, animals and, interdependence of, 



■ — as conditioners of environment, 3, 

 255, 277, 565-6 



— characteristics of, i 



— landforms and, 543-51 

 — , various groups of, 24-74 

 Plasmodium (/)/. plasmodia), 41, 42 

 Plastics, 3, 270 



Plasticity, morphological, 177 

 Platanus (Buttonwood, Plane-tree), 192, 

 194 



P. occidentalism 192 



P. orietitalis, 192 

 Pleistocene epoch, 129, 133, 145, 151, 



173 



— flora etc., 161, 162 



— glaciation, 129, 156-8, 159, 161-5, 



420 



— persistence vs subsequent immigra- 



tion, 161-5 

 Pleodorina, 30, 31 

 Pleurococciis, 30, 3 1 

 Pleurophyllum hookeri, 420 

 Pleuston (hemiplankton), 483, 484, 485, 



497. 503. 504. 506, 515 

 Pliocene epoch, 129, 145, 151 



— flora, 151, 160 



Plum, see Primus domestica 

 Plumed fruits, loi, 104, 105 



— seeds, 99, loi, 104, 105 

 Pluvial periods, 160, 197 

 Pneumatophore (aerating root), 353, 



455, 456 

 Pneumonia, 26 

 Poa (Bluegrass, 



364 

 P. alpina, 103 



X 



Meadow-grass), 361, 



Poa P. ampla (Big Bluegrass), 77 



P. annua (Annual Meadow-grass), 

 120, 249 



P. arctica s.l. (Arctic Meadow-grass), 

 383 



P. flabellata, 421 



P. foliosa, 420 



P. pratensis s.l. (Bluegrass, Meadow- 

 grass), 234, 259 

 Podocarpus, 353 

 Podostemaceae, 463, 498, 504 

 Podzol (podsol), 298, 299, 300 

 Poison, 264, 279, 280 



ivy, 280 



Polar Bear, 401 



— climate, 11, 380—1, 415 



— lands, vegetational types of, 11, 380- 



409. 415-19 



— origin of floras, 171-2 



— oscillation, 167 



— pack-ice, 388 



— tree-line, 212, 343-4, 380 



— Willow, see Salix polaris agg. 

 Poles, wandering of, 167, 170 



Pollen (pollen grain), 63, 68, 70, 71, 104, 

 105, 117-18, 141, 181, 280, 497 



— sac, 63 



— , sub-fossil, 152, 181 



— , transport of, 63, 68, 1 17-18, 181 



— tube, 63, 68, 70, 71 

 — , viability of, 117 



Pollination, 15, 16, 68, 252, 305, 307, 



340 

 Polunin, I. V., 424, 454 

 — , N., 127, 181, 184, 198, 422 

 — , O., 412, 414 

 Polychore (' wide '), 210 

 Polyclimax, 331, 390 

 Polyendemic species, 205, 206 

 Polygons, see Soil polygons 

 Polvgomun viviparum (Viviparous Knot- 



' weed), 385, 386, 387 

 Polymorphs, 223 

 Polyphylesis, 207 

 Polyploid hybrids, 179, 204, 234, 235, 



239 

 Polyploids, 175, 178-80 



— and areas, 178-80 

 — , distribution of, 179 



■ — ; efficiency in competition, 180 

 Polypodium vulgare agg. (Common 



Polypody), 420 

 Polypody, see Polypodium vulgare agg. 

 Polysiphonia, 40, 532 

 Polytopic origin, 188, 207 



— species etc., 205, 206, 207 

 Polytopy and incidence of areas, 206-9 

 Polytrichum, 392, 407 



Pome, 258 



Pomegranate, 258 



Ponderosa Pine, see Pinus ponderosa 



