312 
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 fis. of primrose, 177 
Pine-woods, 273 
Pinguicula: insectivorous pl., 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; fis., 177; d:, 187; 
b infl., 180 ; pollination, 167 
Plant-associations, 224 
Plasmolysis, +92 
Plateaux: climate of, 12; growth- 
form of pls. 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; pls., 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, +112 
Polygonum amphibium, 28, 56; 
Convolvulus, direction of twining, 
116 ;dwmetorum, 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 | 
Anagallis 
BRITISH 
PLANTS 
Popiar: bud-scales, 61; fis.. 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 ; 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, pls. with, 114 
Protandrous flowers, +177 
Protein, 5, 124 ; in seeds, 146, 147 
Protogynous flowers, +177 
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, pls. 
with, 115 
Radish, 216; fr., 188; fleshy root, 
150 
Rainfall, 11 
Rain-forests, 9, 16, 23, 27, 121; 
-shadow, 12 
Ranunculace®, nectaries, 169 
Ranunculus aquatilis, 56, 220, hete- 
rophylly, 51, leaf-form, 50, 51; 
arvensis, 60 ; Ficaria, tubers, 164, 
159 ; sceleratus, 59 
Rape : -oil, 148 ; -seed, 148 
