INDEX 



281 



Picea engehnannii, 244 

 rubra, 243 



mycorrhizas of, 107 

 silchensis, 245 

 Pickerel weed, 229 

 Pigweed, 207 

 colony, 199 

 Pilobolus, 184 



Pine, 69, 125, 136, 241, 243, 244, 247 

 Pinguicula vulgaris, 61 

 Pinus, 69, 70, 125, 136, 222, 241, 243, 



244, 247 

 Pioneer stages of succession, 213-215 

 Pitcher plants, 63, 64, 230 

 Plant associations, 192-194 

 definition of, 194 

 naming of, 193 

 communities, 56-58, 180-191 

 an organism, 180-183 

 distribution of, in United States, 



238-254 

 structure and classification of, 192- 

 202 

 formations, 200 

 pathology, 258 



succession, 187-189, 201, 203-218, 

 270 

 in water, 229-230 

 on clav or clav-gravel, 223-226 

 on rock, 226-229 

 on sand, 220 



typical examples of, 220-230 

 Platanus occidentalis, 224 

 Pleurococcus, 114 

 Plummer, F. G., 241 

 Plums, 112 

 Poa sandbergii, 23 

 Podocarpacese, 113 

 Podophyllum peltatum, 233 

 Poesch, G. H., 129 

 Poison ivy, 24, 91, 224 

 Poliomintha incana, 154 

 Pollen of anemophilous flowers, 66 

 of conifers, 69 



of entomophilous flowers, 74 

 Pollinating insects, 77 

 Pollination, 65-87 

 bird, 87 



cross and close, 65 

 insect, 73-87 

 water, 71, 72 

 wind, 66-71 

 Polygonatum biflorum, 222, 233 



commutatum, 222 

 Polygonum amphibium, 222, 229 

 aviculare, 223 

 persicaria, 223 

 scandens, 91 

 virginianum, 184 

 Poly podium polypodioides, 99, 100 

 Polyporus giganleus, 57 

 siilphureus, 102 



Pond lilies, 167 

 Pondweed, 42, 229 



leaf structure of, 42 



pollination of, 71 

 Potilederia cordala, 77, 229 

 Pool, Raymond J., 166, 253 

 Poole, H. H., 128 

 Poplar, 39, 185 



pollination of, 67 

 Poppy family, latex vessels in, 37 

 Populus, 185 



deUoides, 154, 216, 222 



wislezeni, 154 

 Potassium, 148 

 Potatoes, 20, 40 

 Potentilla, 227 



blaschkeana, 23 



palustris, 222 

 Potomogeton, 42, 229 



leaf structure of, 42 



pollination of, 71 

 Prairie, 248 



clover, 234 



grass, tall, 19 

 Pre vernal season, 232 

 Prickly lettuce, 127, 224 



pear, 36, 223 

 Priestly, J. H., 40 

 Primary bare areas, 201 



seres, 202 

 Primrose, heterostyly in, 75 

 Primula, 75 

 Promiba, 84 

 Proserpinaca, 186 



palustris, 52 

 Prosopis, 249 



leaf structure of, 43 

 Protandry, 76 

 Protective tissues, 32 

 Protogyny, 75 

 Protozoa, 150 

 Prunus, 223, 245 

 Psamosere, 202 

 Psedera quinquefolia, 92 

 Pseudo-epiphytes, 98 

 Pseudoisuga taxifolia, 103, 104, 244 

 Psychrometer, 140, 266 

 Psychrometric tables, 141 

 Ptelea, 184 

 Puccoon, 221 

 Pulvinas, 50 

 Pyrola elliptica, 222 



Quadrat methods, 267-269 

 Ouercus, 100, 125, 216, 223, 227, 239, 

 245, 247 



Rabbitbrush, 251 



Radicvla aquatica, leaves of, 52 



