312 



BRITISH PLANTS 



Pimpernel, fr., 187, *188 

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

 rhiza, 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 



Pinguicula : insectivorous pi., 130, 

 * 131 ; grandiflora, 213 ; lusitanica, 

 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, f92 



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- 



t 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 



Polyearpic plants, f!12 



Polygonum amphibium, 28, 56 ; 

 Convolvulus, direction of twining, 

 116 ;dumetorum, 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 

 AnagaUis 



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 

 j 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 ; yield per acre, 149 

 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, f 177 

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

 Protogynous flowers* f!77 

 Protoplasm, 92, 93 

 Prunus spinosa, thorns, 140 

 Psamma, 62 ; -association, 281 ; 



leaf, 40, *43 ; binding power of, 



281 



Pseudocarp, 185, 193 

 Pulse, 147 

 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 

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



-shadow, 12 



Ranunculaceae, nectaries, 169 

 Ranunculus aquatilis, 56, 220, hete- 



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



arvensis, 60 ; Ficaria, tubers, 154, 



159 ; sceleratus, 59 

 Rape : -oil, 148 ; -seed, 148 



