324 



BRITISH PLANTS 



Pimpernel, fr., 187, *188 

 Pine, 22, 39, 272 ; leaf, 42 ; myco- 

 rHza, 125 ; pollination, 163, 167 ; 

 former range of, 273 ; resin, 142 ; 

 seeds, 183, 195 ; shade cast by, 

 273 ; stomata, *40 

 Pineapple, 194 



Pin-eyed fls. of primrose, 177 

 Pine-woods, 273 



Pinguicvla: insectivorous pi., 130, 

 *131 ; grandiflora,2\Z ilusitanica, 

 213 ; vulgaris, 130 

 Pinks, infl., 180 

 Pistil, 162 

 Pitcher-plants, 132 

 Pith, *45 

 Plains, 12 



Plane, bud-protection, 61 

 Plantain, 37; fls., 177; fr., 187; 



infl., 180 ; pollination, 167 

 Plant-associations, 224 

 Plasmolysis, 192 



Plateaux : climate of, 12 ; growth- 

 form of pis. on, 36 

 Plum: bud-scales, 61 ; cultivation of, 

 149; fr., 184, 192, 194; extra- 

 floral nectaries, 173 ; suckers, 155 

 Poa alpina : fecundity of, 108 ; vivi- 



pary, 160, *161 ; annua, 60 

 Pod, 188 

 Poisonous fruits, 149 ; pis., 152 ; 



seeds, 138 

 Polar regions : duration of sunlight, 

 67 ; growth-form in, 36 ; xero- 

 phytic factors of, 35 

 Pollen, 162 ; -bread, 168 ; -fls., 168 ; 

 -grains, 162, 163 ; -tube, *163 ; 

 of wind-pollinated fls., 166 ; of 

 Zostera, 166 

 Pollination, 163, 164 ; agents of, 166 ; 

 by birds, 176 ; cross-, 164, 166 ; by 

 insects, 167 ; self-, 164, effect on 

 the stock, 165 ; prevention of, 176 ; 

 by slugs, 176 ; a form of symbiosis, 

 133 ; by water, 166 ; by wind, 166 

 Polycarpie plants, tll2 

 Polygonum amphibium, 28, 56 ; 

 Convolvulus, direction of twining, 

 116 ;dame(orM»i, imperfect twiner, 

 117 

 Polypody, epiphytic, 121 

 Pome, 193 



Ponds, lowland-, veg. of, 236 

 Pondweeds, 233. See Potamogeton 

 Pools, highland-, veg.' of, 238 

 Poor man's weather-glass, 217. See 

 AnagaUia 



I Poplar : bud-scales, 61 ; fls., 176 

 pollination, 167 , seeds, 195 ; 

 suckers, 155 



Poppy, 216 ; fr., 187 ; opium-, 152 ; 

 seeds, 146, *147, 195; summer- 

 annual, 107 



Pore-space, 85 



Potamogeton crispus, brood-buds, 

 *51, 54 ; leaf-form, 50, *51 



Potash, silicate of, 81 



Potato, 62 ; a source of alcohol, 151 

 food-reserve in tubers, 150 

 "seed"-, 149; starch, 145 

 tubers, *111 ; repr. by tubers, 

 149, 159 



Potato, sweet, 150 



Potentil, honey, 172 



Poterium, pollination, 167 



Prairies, 9, 15, 23, 35 



Prickles, 139, 140 



Primrose : dimorphism, 177 ; honey, 

 173 



Privet : berries, 149 ; bud-scales, 61 ; 

 origin of variegated vars., 154 ; 

 effect of pruning, 109 



Prostrate stems, pis. with, 114 



Protandrous flowers, tl77 



Protein, 5, 124 ; in seeds, 146, 147 



Protogynous flowers, tl77 



Protoplasm, 92, 93 



Protozoa, soil, 96 



Prunus spinosa, thorns, 140 



Psamma, 62; -association, 281; 

 leaf, 40, *43; binding power of, 

 281 



Pseudocarp, 185, 193 



Putrefaction, 78, 93 



Puzstas, 20 



Pyrus torminalis, 214 



Quartz, 80 

 Quinine, 142, 152 



Raceme, 178, *179 



Radical and cauline leaves, pis. 



with, 115 

 Radish, 216; fr., 188; fleshy root, 



150 

 Rainfall, 11 

 Bain-forests, 9, 16, 23, 27, 121 ; 



-shadow, 12 

 Ranunculace89, nectaries, 169 

 Banunculii^ aguatUis, 56, 220, hete- 



rophylly, 51, leaf-form, 50, 51 ; 



arvensis, 00 ; Ficaria, tubers, 154, 



159 ; sceleratus, 59 

 Rape : -oil, 148 ; -seed, 14S 



