GENERAL INDEX 
Oils, 5 ; antiseptic, 136 ; fixed, 142 ; 
as a food-reserve, 146, in seeds, 
147 ; volatile, 143, 151 ; in xero- 
phytes, 42 
Oily seeds, 148 
Old man’s-beard, 217. 
Vitalba 
Olive, 23 
See Clematis 
Onion: bulb, 150; bulbils, 160; infl.. | 
181 ; seeds, *146 ; sugar, 146, 150 
Ononis arvensis, spines, 44 
Open associations, 277 ; habitats, 16 | 
Opium, 143, 152 
Orange, 23 
Orchid: bird’s-nest (see Neottia) ; 
coral-root (see Corallorhiza) ; fr., 
189; honey, 173; infl, 180; 
pollination, 177; seed, 195; 
tubers, 111 
Origin of species, 202 
Orobanche, 127 
Orobus, fr., *189 
Osier-beds, 244 
Osmosis, 25, 91 
Ovary, 162, 183 
Ovule, 162 
Oxalis, 62 ; aril, 196 ; cleistogamous 
fls., 165 ; fr., 189 ; oxalic acid in, 
143 ; rhizome, 154; seeds, 196; 
sleep-movements of leaves, 70, 
*71. See Sorrel 
Oxtongue, 60, 217. 
echioides 
Oxygen, 6, 7; in air, 78, 79; in 
water, 48, 50; in soil, 88 
See Helminthia 
Peony, 168 
Palisade-tissue, 41, *72 
Palm, 23 ; -oil, 148 
Pampas, 20 
Panicle, 178, 179 
Panicum miliaceum, 147 
Papaver somniferum, alkaloid of, 
143, 152 
Pappus, 195 
Parasites, 6, +125, 206 ; partial, 126 ; 
total, 126; hemi-parasites of 
meadow-land, 263, of natural 
pasture, 257 
Parallel development, 105 
Parietaria officinalis, fls., 177 
Paris quadrifolia, 214 
Park-land, 17, 126 
Parsley, 181 
Parsnip, 150 
Partial parasites, 126 ; saprophytes, 
125 
ol! 
Passion-flower, tendrils, *115 
Pastures, 15, 18, 20; alpine, 230, 
251, 259 ; artificial, 20, 261, weeds 
of, 264; limestone-, 230, 259; 
lowland-, 230, 258 ; natural, 257 ; 
sub-alpine, 230, 258 
Pea: fr., 188; pollination, 165; 
protein of, 147 ; root-nodules, 95 ; 
seeds, 146, 195; tendrils, 118. 
See Lathyrus 
Peach : fr., *192 ; origin of, 205 
Pear : bud-scales, 61; cultivation of, 
149 
Peat, 17, 83, 93, 94, 244, 248, 254 ; 
absorptive power of, 87; -bogs, 
246, 248, xerophytic factors of, 
35; moorland-, constitution of, 
249, comparison with marsh-peat, 
249, conditions necessary for 
formation of, 248 ; water-capacity 
of, 87. See Humus 
Pedicularis, 59; parasitic nature, 
126 
Pelargonium : fr., 190, 195; infl., 181 
Pellitory. See Parietaria officinalis 
Pennyeress, 216 
Pepper, 151 ; -mint, 151 
Percolation in soils, 87 
Perennating organs, 62, 109 ; struc- 
tures, 762 
Perennials, 108; evergreen, 109; 
herbaceous, 109, 115, 145 ; tropo- 
phytic, 59 ; xerophytic, 59 
Perianth, 7162 
Pericarp, 183 
Permeability of soils, 87 
Peruvian bark. See Cinchona 
Petals, 162 
Petioles : of Acacia, 43, *44; of float- 
ing aquatic leaves, 51 
Phaseolus vulgaris, twiner, 116. 
Scarlet runner. 
Phleum arenarium, 60 
Phloem, *45 ; in aquatics, 49 
Phormium tenax, 42 
Photosynthesis, +4, 66, 78 
Phragmites, 62; -associations, 242, 
245 
Phylloclade, 44, *45 
Phyllode, 43, *44, 46 
Physical action of water on rocks, 
81 ; properties of soil, 85 
Physiognomic groups, 16 
Physiological dryness, 34, 85 
Physiology, +103 
Pillwort. Ses Pilularia 
Pilularia, 28, 50 
See 
