5/o 



BOTANY OF THE LIVING PLANT 



loss, not to a want of water out- 



side it, 162. 

 Phytophthora infestans, Potato-Fun- 



gus, 410, 412, 416-421 (Figs. 352- 



356) ; sexual reproduction in, 419. 

 Pileus, domed head of Mushroom, 453. 

 Piliferous layer, the superficial layer 



of the root, which bears the root- 



hairs, 71 (Fig. 53), 75 (Fig. 57). 

 Pilobolus, explosive dispersal of, 425. 

 Pinguicula, carnivorous habit of, 207, 



208. 

 Pinus, Chap, xix., p. 302 ; cambium 



of, 48 (Fig. 34). 

 Pinus Laricio, male flowers, 304 



(Fig. 246) ; female flowers, 308 



(Fig. 250). 

 Pinus montana, male flower of, 309 



(Fig. 251). 



Piptocephalis, parasitism of, 424. 

 Pistil, an old term for the gynoecium, 



or carpellary region of the flower, 



221, 252 (Figs. 198, 199). 

 Pistillate, applied to flowers or plants 



which bear carpels, but not stamens, 



222 ; by abortion in Lychnis, 



236 (Fig. 184). 

 Pisum sativum (Garden Pea), recep- 



tive cells in root, 126 (Fig. 87 bis) ; 



used in Mendel's experiments, 473 ; 



523 ; analysis of, 542. 



Pit, an area of cell-wall that remains 



thin, 28 (Figs. 17, 18, 19, B). 

 Pit-membrane, permeable, 86. 

 Pith, 34 (Fig. 21), 35. 

 Placenta, the point or surface of 



insertion of the ovule or ovules, 



255 ; free-central, 508 (Figs. 412, 



Placentation, the mode of insertion 

 of the ovules, 255. 



Plankton, floating organic life, 401. 



Plantago, haustoria of embryo-sac, 

 281. 



Plant-communities, plants of a local- 

 ity subjected to, and adapted for 

 life under common conditions, 175. 



Plant-population, 296. 



Plasmolysis, separation of the proto- 

 plast from the cell-wall, by its 

 contraction, due to loss of water, 

 24 (Figs. 14, 15). 



Plastids, minute bodies in the cyto- 

 plasm, which multiply by fusion, 

 and give rise to chloroplasts, 

 chromoplasts, or leukoplasts : 18 

 (Fig- 9). 



Platanthera, young plant of, 201 

 (Fig. 152). 



Plectascineae, 432. 



Pleiomery, in the flower, where the 

 number of parts of one category 

 is greater than the fundamental 

 number for that flower. 232. 



Pleurocarpic, of Mosses which fruit 

 laterally, 359. 



Pleurocladia, zoospores of, 382 (Fig. 

 320). 



Pleurococcus, 391. 



Plum, analysis of, 544. 



Plumule, the apical leafy bud of the 

 embryo, 7. 



Poa alpina, viviparous habit of, 215. 



Podosphaera clandestina, Hawthorn 

 Mildew, 431. 



Polar nuclei, fusion of in Lily, 272 

 (Fig. 216). 



Pollen, the microspore of Flowering 

 Plants, 221. 



Pollen-grains, of Flowering Plants, 

 245, 247 (Figs. 193, 194) ; develop- 

 ment of, 249 (Figs. 196, 197) ; 

 germination of, 257, 265 ; of Pine, 

 309 (Fig. 251), 310 (Figs. 252, 253), 



324- 



Pollen-mother-cells, those cells which 

 after tetrad-division give rise to 

 pollen, 249 (Figs. 196, 197). 



Pollen-sac, the microsporangium of 

 Flowering Plants, containing the 

 microspores, or pollen-grains, 222 ; 

 246 (Fig. 193) ; development of, 

 249, 250 (Figs. 196, 197). 



Pollen-tetrad, a group of four cells, 

 resulting from the tetrad-division 

 of a pollen-mother-cell, 249 (Fig. 



194). 



Pollen-tube, formation of, 265 ; cul- 

 ture solutions for, 267 ; influences 

 upon growth of, 267, 269 (Figs. 

 2ii, 214) ; of Pine, 312 (Fig. 253. 

 254) ; of Zamia, 315 (Fig. 257). 



Pollination, the transfer of pollen- 

 grains from the pollen-sac to the 

 stigma, 264. 



Pollinia of Orchis, 500 (Fig. 402). 



Polycarpicae, 493, 509. 



Polygonum viviparum, bulbils in 

 place of flowers, 214. 



Polypodium, dorsiventrality of, 175 

 (Fig. 131) ; archegonia of, 344 

 (Fig. 285). 



Polyporus, 404, 451 (Fig. 386) ; 

 P. igniarius, 452 (Fig. 388). 



