INDEX 



381 



Pruning, 51 



Prunus, flower of, 189, 362 



Pteridophyta, 12, 14, 325-342 



reasons for success of, 154 

 Puccinia, 297, 298 

 Puff-ball, 301, 302 

 Purpose, in plant activities, 154 

 Pyrenoid, 267, 274 

 Pyrenomycetes, 294 



Quillwort, 338 



Raceme, 193, 362 

 Radial section of wood, 107 

 Radicle, 198, 199 

 Ranales, 362 

 Rays, in wood, 107 

 Receptacle, 188 



of Fucus, 280 

 Recessiveness, 213 

 Red algae, 282 



cedar, galls on, 169 

 Reduction division, 187, 188, 217, 

 251 



of chromosome number, 186-188 

 Regular flower, 191 

 Regulation, 154, 246 

 Reproduction, 182-203 



asexual, 182, 183 



sexual, 184 



vegetative, 182 

 Reproductive organs, 20 

 Reserve cellulose, 121 

 Resistance, to heat and cold, 158 

 Respiration, 20, 125-133 



aerobic, 129 



anaerobic, 131 



as index of activity, 129 



contrasted with photosynthesis, 

 130 



in every living cell, 129 



of plants and animals, 131 

 Response to stimulus, 155 



Rhizobium, 32 

 Rhizoid, 253, 313 

 Rhizome, 93, 94 

 Rhizopvs, 289 

 Rhodophyceae, 282 

 Riccia, 313 



Ricciocarpus, 312, 313, 314 

 Rice, starch grains of, 120 

 Rivularia, 266 

 Rock particles, in soil, 24 

 Rockweed, 12 

 Root, 19, 40-56, 325 



absorbing region of, 42 



as prop, 55 



external structure of, 40 



fibrous, 19, 40, 41 



internal structure of, 46, 47 



lateral, 41 



of climbing plants, 55 



of epiphytes, 55 

 Root-cap, 42, 143, 144 

 Root-hair, 19, 42, 43, 44 

 Root-pressure, 54 



in sap ascent. 111 

 Rootstock, 93, 94, 184 

 Root-tubercles, of legumes, 33, 34 

 Rosales, 363 

 Rubiales, 364 

 Runner, 184 



Run-off, from soil surface, 24 

 Rusts, 297 



Sabatia, evolution of species in, 232, 



233 

 Saccharomycetes, 295 

 Saccharomyces, 295 

 Sac fungi, 292 

 Salts, absorption of, 53, 54 

 Sambucus, variation in leaves of, 208 

 Sap, ascent of, 111 

 Sap-cavity of cell, 45 



development of, 141 

 Saprolegnia, 291 

 Saprolegniales, 291 

 Saprophyte, 173, 284 

 Sap-wood, 105, 106 



