778 
Plant, cell, 41 
cigar, 570 
communities, 616 
dicecious, 264 
pitcher, 629 
polygamous, 264 
seed, 7 
tissues, 111 
xerophytic, 164 
Plant Succession, 621 
Plantaginacea, placentation in, 288 
Plantaginis Semen, 603 
Plantago, 44, 301, 603 
Plantago arenaria, 603 
Plantago lanceolata, 603 
Plantago ovata, 603 
Plantago Psyllium, 602, 603 
Plantain, 259, 603 
Plants, aquatic, 164, 617 
carnivorous, 621 
classification of, 323 
desert, 617 
general characteristics of, 6 
groups of, 12, 328 
intermediate, 617 
marsh, 618 
naming of, 323, 329 
relation of, and animals, 29 
relation to animals, 621 
salt, 617 
water, 617 
Plasma membranes, 19, 22 
illustrating, successive stages of, 154 
Plastids, 42 
Platystemon, 524 
Plum, 305, 535 
Plumule, 311 
Pod, 301 
Podophyllum, 519 
Podophyllum emodi, 519 
peltatum, 519 
Fig. of, 521 
petiolar structure of, 245 
Podophyllum Indicum, 519 
Poison Hemlock, 516 
Fig. of, 578 
Poisons, 33 
Poke, Family, 514 
Root, 175, 614 
Polemoniales, 590 
Pollen, 278 
chamber, 449, 458 
grain, 280 
mother cells, 278, 474 
stages in germination, 293 
Pollen grains, 282, 457 
Fig. of, 281, 450 
pine, 281, 450 
Pollens, Hay-fever, 283 
Pollination, 290 
cross, 291 
in erythronium, 475 
in pine, 450 
self, 290 
Pollinia, 282, 283, 589 
Polycotyledony, 227 
Polyembryony, 479 
Polygala, 103, 283 
lutea, 549 
pollen of, 283 
