INDEX 



311 



normal succession, 274 



Nostoc, 105 



numerical alternation, 293 



nut, 132 



nutrient salts, 18, 68 



Nymphwa, 168, 242 



nyctanthous flowers, 130 



nyctotropism, 89 



oblate cells, 172 

 Odontoglossum, 131 

 CEdogonium, 243 

 CEnothera, 190, 200 



lamarckiana, 190 

 offsets, 115 



offshoot-distributed plants, 242 

 Onagra, 120, 122, 182, 260 

 oncospores, 243 

 open formations, 234, 235, 271 

 optimum, 95 

 Orchis, 117 



organs of dissemmation, 241 

 origin by adaptation, 192 



by descent before Darwin, 187 



by hybndation, 197 



by mutation, 196 



by variation, 195 



of new forms, 185 

 "Origin of Species," 187, 188, 189 

 osmosis, 45 



in root-hairs, 46 

 osmotic pressure, 55, 62 

 Ostrya, 242 



outline of sun and shade leaves, 178 

 Oxalis, 121,247 

 oxides, 19 



Pachylophus hirsulus, 129 

 palisade cell, 172 



leaf, 183 



tissue, 57, 151, 176 

 Panicum, 293 



parachute disseminules, 242 

 parasites, 104 



kinds of, 104 

 parental care, 116 

 Parietaria, 126 

 pathology, 5, 6 

 Pedicidaris procera, 164, 184 

 Penicillium , 105 



Pentstemon, 120, 157, 165, 293, 294 

 pepsin, 100 

 pepo, 132 

 periblem, 39, 41 

 pericycle, 41 



periodicity of growth, 110 

 period of flowering, 128 

 permanent quadrat, 204, 208 

 perquadrat, 204 

 petasospores, 242 



phenology, 131 

 Philotria, 168 

 phloem, 42, 52 

 phosphates, 19, 101 

 phosphorus, 18, 101 

 photometer, 72 

 photosynthesis, 81, 104 



chemical changes during, 82 



formulae, 82 



measurement of, 83 



rays active in, 81 

 phototropism, 71, 87 

 phyad, 155 

 phyllode form, 162 

 Phy sails, 242 

 phj^sical barriers, 266 



factors, 30, 36 



factors, zones due to, 297 

 physiographic classification, 233 

 Plantago, 126 

 plant body, types of, 154 

 plant -distributed species, 242 

 plant formation, 215 



temperatures, 92 

 plasmolysis, 47 

 plastic forms, 186 



species, 192 

 plasticity, 185, 265 

 plerome, 39, 41 

 Pleurococcus , 105 

 plumed disseminules, 242 

 pod, 132 



point readings, 33 

 polarity, 108 



Polemoniurn speciosum, 267 

 pollen, amount of, 116 



flowers, 127 



production, 116 



protection by movement, 120 



protection of, 118 



seasonal protection of, 121 



source and distribution of, 124 



structural protection of, 119 

 poUination, agents in, 125 



by insects, 126 



kinds of, 124 

 polychronic, 201 

 polydemic, 268 

 polydemics, 184 

 polygamy, 122 

 polygenesis, 199 

 Polygonutn, 163 



aviculare, 261 

 polytopic, 201 

 pome, 132 

 Populus, 120, 126 

 porosity, 18, 20 

 Portulaca, 122 

 position, effect on competition, 256 



of disseminules, 244 



