INDEX 
Outbreeding, 254-256 
Ovary, 5, 6, 205-206, 223*, 272; of 
angiosperms, 429-430; of Hibiscus, 
207* ; superior and inferior, 274 
Ovules, 6, 205-206, 221-222 ; of Coni- 
Ferales, 421-423; of cycads, 408* ; 
of Spermatophyta, 408. See Mega- 
sporangium 
Ovuliferous scales of pine, 422 
Oxidation, 48-53 
Oxygen, in animals, 47; in carbohy- 
drates, 44; molecule of, 10; and 
photosynthesis, 43-49 ; in proteins, 
18; source of, 10; and stoma, 29 
Padina australis, 339* 
Paleozoic Age, 419 
Palisade chlorenchyma, 30, 38 ; in Eu- 
calyptus, 37*; and transpiration, 
61-62 
Palmella stage, 319-320 
Palmitin, 291 
Palms, 75, 105*, 106, 115, 174, 176, 184, 
291, 434*, 435, 436 ; rattan (Calamus), 
81* 
Pandanus tectorius, 178*, 199 
Papain, 295 
Papaya (Carica papaya), flowers of, 
209* ; leaf of, 73* 
Paper, 151-152 
Para rubber (Hevea brasiliensis), 128 
Parallel veins, 28 
Paraphyses, 350*, 351 
Parasites, 12, 13, 170, 309, 345, 439; 
leaves of, 94; lichens, 366; rusts, 
357 ; smuts, 355-356. See Fungi and 
Bacteria 
Parenchyma, 31*, 33*, 35*, 36, 117-119 
Parsnips, 208 
Passage cells, 194 
Peach, drupe of, 278* 
Peanut, 293*, 303 
Peas (Pisum sativum), 77-78, 79; and 
heredity, 236-242, 250 
Peat, 382 
Peat mosses, 382 
' Pediastrum, 324* 
Pedicel, 209 
Pellia, 376* 
Peltate leaves, 71, 72* 
Peperomia pellucida, cross section of 
leaf of, 65* 
Percolation, 186-187 
Perennials, 14; pith of, 120 
Perianth, 207, 209 
Pericarp, 278, 286 
477 
Pericycle, of dicotyledonous stems, 
126-127 ; in root, 193 
Perisperm, 281 
Peristome, 382* 
Perithecia, 352* 
Persimmon (Diospyros kaki), 292* 
Petals, 87, 207, 218 ; source of oxygen 
for, 50 
Petiole, 79, 110-111; of elephant’s-ear, 
139* ; in leaf mosaics, 112; of leaves, 
26, 27; modified, 77-79, 82*; of a 
water lily, 54*. See Floats 
Peziza, 352 
Phaeophyceae (brown algz), 337-340; 
Ectocarpus, 339-340; and Rhodo- 
phyceae, 340 
Phaseolus lunatus (lima bean), germi- 
nation of, 297*; seed of, 281* 
Phaseolus radiatus (mungo bean), 110* ; 
cells of, 289* ; root of, 192*, 195%, 
196*, 197* 
Phases of matter, 7 
Phellogen, 153-155 
Phloém, 98, 121, 387-388 ; in conduct- 
ing system of leaf, 37; of dicoty- 
ledons, 123, 125; in Hrythrorylon 
coca, 85* ; in Ixora, 33*; in scle- 
renchyma of leaf, 37, 38 
Phosphorus, 18, 175 
Photosynthesis, 4, 166*, 168*, 169* : 
and absorption, 21; in chloro- 
plastids, 24; in collenchyma, 120; 
definition of, 42; demonstration of, 
46-47; energy, 48-49; in grasses, 
38, 39; in leaf, 26; in palisade 
_ chlorenchyma, 80; in parenchyma 
cells of cortex, 118; process of, 42- 
43 ; products of, 48-46 ; relation of, 
to animals, 47-48 ; and respiration, 
49-51; in roots, 196, 199; in special- 
ized leaves, 77-78 ; in spines, 91 ; in 
spongy chlorenchyma, 31; in stem, 
165, 169-170; and transpiration, 55, 
63; in Venus’s-flytrap, 84; in ver- 
tical leaves, 38-39; in water lilies, 
80; and xerophytic leaves, 443 
Phototropism, 108-110, 112-113 
Phycomycetes, 344-851; Saprolegnia, 
344-346 ; Zygomycetes, 347-850 
Phyllocladus protractus, the leaflike 
branches of, 169* 
Phyllotaxy, 101--103 
Physiology, 1 
Picea sitchensis, 444* 
Pine, 403%, 404*, 405*, 420*, 426* ; al- 
ternation of generations in, 427; 
