5i8 



SUBJECT INDEX 



Geophytes, 449, 451 

 Geotropism, of mistletoe, 222 ; of 

 peduncles, 404 ; of roots, 22, 

 29s ; of seedlings, 438 ; of 

 twining plants, 296 

 Germination, epigeal, 436 ; hypo- 

 geal, 436 

 also under Seed 

 Growth, compound interest law of, 

 440 ; grand period of, 441 ; 

 mode of, 439 

 factors influencing, 443 sqq. 

 an autocatalytic reaction, 442 

 curves, 440 sqq. 

 Guard cells, 84 



hydrogen ion concentration of, 

 107 ; metabolism of, 103, 

 105, 109 ; osmotic pressure 

 of, 104, 106 ; suction force 

 of, 104 

 Guttation, 202 



Hairiness, of adult leaves, 181 ; of 

 marsh plants, 181 ; of xero- 

 phytes, 180 

 distribution of, 181 ; experi- 

 mental modification of, 183 

 and transpiration, 180 sqq. 

 seasonal, 184 

 Hairs, nature of, 180 



absorptive, 74 ; fodder, 359 ; 

 stinging, 308 

 Halophytes, 197 

 Haptotropism, of roots, 23 ; of 



tendrils, 297 

 Helophytes, 451 

 Hemicryptophytes, 451 

 Herbaceous plants, mechanical fea- 

 tures of, 289 ; root systems 

 of, 25 sqq. 

 Heterostyly, 388 

 Holard, 54 

 Honey guides, 364 

 Hormones, wound, 329, 353 

 Humus, 4, 5 



collection of, by roots, 73 ; col- 

 lection of, in pitchers, 73 ; 

 effect of, on hydrogen ion 

 concentration, 11 

 soils, 19 

 Hybrid vigour, 322, 460 

 Hybridisation, and evolution, 322, 

 463 ; and parthenogenesis, 

 328 

 Hydathodes, 202, 359 

 Hydrogen ion concentration, 10, 42 

 of guard cells, 107 

 effect of, on roots, 42 



Hydrophily, 354, 378 

 Hydrophytes, 200, 451 

 Hydropotes, 89 

 Hydrotropism of roots, 23 

 Hypocotyl, contractile, 288 

 curvature of, 438 



Inbreeding, 322 



Individuality, 315, 461 



Insectivorous habit, origin of, 281 



Insectivorous plants, 217, 267 



assimilation of, 281 ; supply of 

 nitrogen compounds of, 281 ; 

 supply of organic food of, 

 281 ; supply of salts of, 281 

 capture of prey by, 268, 269, 

 270, 272, 274, 276, 277, 278, 

 280, 282 ; utilisation of prey 

 by, 269, 270, 271, 273, 27s, 

 276, 277, 279, 281 



Insular plants and wind pollination, 

 361, 378 



Ions, absorption of, 67 



Land flora, evolution of, 316 sqq. 

 Leaf- fall, 448, 451 sqq. 



and climatic changes, 453 ; and 



transpiration, 186 

 periodic, 451 ; summer, 186 ; 

 winter, 186, 451 

 Leaf mosaic, 118 

 Leaf spines, 192 

 Leaf tendrils, 192 

 Leaves, 83 sqq. 



of aquatics, 293 



absorption of light by, 113; 

 avoidance of shading by, 

 116 sqq. ; adjustment of, 

 118 ; arrangement of, 115 

 sqq. ; development of, 452 ; 

 fiixed light position of, 120 ; 

 mechanical features of, 292 

 sqq.; movements of, 119, 

 120, 187, 270, 311 ; orienta- 

 tion of, and diffuse light, 120 ; 

 orientation of, and sunlight, 

 123 ; profile position of, 124 ; 

 rolling in of, 179, 189 ; 

 structure of, 83, 126, 127 ; 

 water content of, 160 

 tentacles on, 268 

 and alpine environment, 157 

 replaced by stem, 193 sqq. ; 



replaced by root, 198 

 cricoid, 189 ; eupho tome trie, 

 125 ; needle, 188 ; panpho to- 

 metric, 125, 154; papillose, 

 204 ; scale, 189, 229, 230 ; 



