Odum, E. P., 312 

 Oedogoniiim, 500 

 Ogg, W., 223 

 Oil of citronella, 275 



— of Geranium, 275 



— of Lavender, 275 



— of Rosemary, 275 

 - — seeds, 282 



— storage in plants, 33, 35, 479, 517 

 Oils, 3, 234, 235, 265, 266, 268, 274, 



275 

 Ointments, 266 

 Okra, 258 



Oldest known rocks, age of, 128, 145 

 Olea (Olive), 235, 258, 265, 354 

 O. cnropaeo (Olive), 242, 355 

 Oligocene epoch, 129, 145, 151 

 Oligotrophic lakes (waters), 318, 476-8 



— water, 325, 462-3, 476, 477, 480, 



545 



, Desmids and, 318, 477, 501 



Olive, see Olea and O. europaea 



Oliver, F. W., 127 



Oltmanns, F., 540 



Onion, see Allium cepa 



Ontario, 130 



Ontogenetic change, 217, 322 



Oostmg, H. J., 312, 332, 378, 578, 580 



Ooze, 496, 497, 506, 539 



Open Birch forest, 344 



— community, 397, 398, 447 



— habitat, 81, 114, 120, 126, 163, 165, 



218, 296, 374, 387, 395-9, 544 



, competition weak in, 163, 374 



soil plants, 108, 544 



Ophioglossum vulgatiim (Common 



Adder's-tongue), 61 

 Opium, 263, 266, 267 



— Poppy, see Papaver souiniferum 

 Optimum conditions, competition etc. 



and, 302, 482, 485 

 Opimtia (Prickly-pear), 248, 574 

 Orache, see Atriplex 

 Orange, 258 



— blossom oil, 275 

 Orchard-grass, see Dactylis glomerata 

 Orchidaceae (Orchids), 72, 73, loi, 104, 



105, 352, 434, 436, 442, 462 

 Order, 24 



Ordovician period, 129, 132, 145 

 Organic matter, 302-4 

 Organisms, oldest known fossil, 130 

 — , most primitive, 129 

 Origin of crop plants, 223-39, 253-4 

 Oryza sativa (Rice), 224, 257, 261, 282 



, world production of, 225, 229 



Osage orange, 274 



Oscillaton'o, 28, 370 



Osmotic changes, 369, 508, 523 



— pressure, variation in, 523 



— value of cell-sap, 452 



INDEX 617 



Osmunda regalis agg. (Royal Fern), 202, 



203, 342 

 O. regalis subsp. spectabilis, 202, 203 

 Otto of roses, 275 

 Outliers (of forest), 292, 293, 295, 345, 



347. 348, 350 

 Outwash plain, 543, 545 

 Ovary, 63, 67, 69 

 Overgrazing, Cactaceae and, 360, 362, 



577 

 — , effects of, 307, 308, 309, 361, 362, 



569 

 — , erosion and, 307, 309, 569 

 — , plant indicators of, 577 

 Ovule, 62, 63, 68, 69, 70, 71 

 Oxalis (Wood-sorrel), 124 



O. acetosella (Wood-sorrel), 340 

 Oxford Botanic Garden, 102, 119 



— Ragwort, see Senecio sqiialidus 

 Oxycoccus (Cranberry), 258, 501, 560 

 Oxygen /carbon dioxide balance in sea, 



509-10 



— concentration, seaweeds and, 523 



— content of fresh water, 476, 486, 488 



— distribution in lake water, 476-8, 

 486 



— occurrence in sea, 509, 510, 523 

 — , phytoplankton and, 488 

 — , role of, in soil, 302 

 Oxygenation as limiting factor, 319 

 Oxylophyte, 302 

 Oxyria digyna (Mountain Sorrel), 108, 



Oysterleaf, see Mertensia mariluna agg. 



Pacific coast forest, 67, 348, 376 



— Ocean, 167, 169, 457, 529, 534 

 benthos, 534, 535 



, islands of, 109, 167, 194, 259 



, temperature distribution in water 



of, 510 



— Silverweed, see Potentilla egedii 



agg. 

 Pain, relief of, 263, 264 

 Paint and varnish manufacture, 265, 266 

 Palaeotropical discontinuity, 194 

 Palaeozoic era, duration of, 129, 145, 

 146 



, flora of, 130, 132-6, 138, 139, 



141, 143, 144, 146 

 Pale-laurel, see Kalmia 

 Paleocene epoch, 129, 145, 151 

 Palm-kernel oil, 266 



— oil (see also Elaeis guineemis), 235, 



266 

 savanna, 445 



— w'ine, 261 



Palmae (Palms, Palm family), 73, 187, 

 211, 351, 352, 355, 425, 427. 444. 

 445, 457, 460, 461, 463 



— , Climbing, 427, 431 



