INDEX 



Pollen, 826, 830, 831, 834, 836, 839, 842, 

 850, 852; foreign, 855; impotent, 854; 

 own, 855 ; prepotent, 854, 855 ; sac, 30; 

 tube, 826, 830, 832. 



Pollination, 829, 845 ; bud, 866 ; close, 829, 

 852, 863, 866, 869; contact, 862; cross, 

 829, 836, 852, 854, 859, 866, 867 ; gravity 

 863 ; insect, 838, 839, 840, 841, 842, 847, 

 850,857; self, 829, 863 ; water, 837, 838 ; 

 wind, 833, 834, 835, 837, 838. 



Pollinium, 830, 851. 



Poly arch bundles, 683. 



Polycarpic plants, 886. 



Polyembryony, 820. 



Polygala, 865. 



Polygonatum, rhizome, 671. 



Polygonum. leaf variation, 575, 



Polypetalous flowers, 825, 826. 



Polystichum, sporangia, 815. 



Polytrichum, habit, 613; vascular bundles, 

 686. 



Pond associations, 540, 940. 



Pondweed, leaf section, 537. 



Poplar; Populus, absciss layer, 583; leaf 

 section, 574; twigs, 736 . 



Porcupine grass, fruit, 929. 



Pore, 612, 68 1 ; air, 557. 



Portulaca, leaf section, 533. 



Potamogeton, leaf section, 537. 



Potato, starch, 912; tuber, 674, 720; varia- 

 tion, 727. 



Predisposition, 768. 



Prepotent pollen, 854, 855. 



Pressure, osmotic, 493, 627 ; turgor, 566, 

 621. 



Prickle, 742, 783, 932. 



Prickly pear, 725. 



Primary conductive tissue, 680, 682, 683, 

 686 ; root, 491, 496, 498, 500. 



Primrose, flowers, 854; hydathode, 621; 

 evening, capsules, 920; rosettes, 714. 



Primula, flowers, 854; hydathode, 621. 



Privet, lenticel, 661. 



Proboscis, 841. 



Procambium, 684. 



Profile position, 546, 547, 578. 



Progeotropism, 499. 



Progressive variability, 759. 



Prohydrotropism, 499. 



Pronuba, 864. 



Propagation, 502, 503, 505, 805 ; root, 505. 



Propagule, 805. 



Prop root, 514, 515. 



Propulsion, 919. 



Prosenchyma, 679, 686, 696. 



Proserpinaca, leaf section, 534; leaf varia- 

 tion, 592, 593, 595. 



Prostrate plants, 647. 



Protandry, 837, 840, 853. 



Protection, bud, 640; flower, 857, 869, 870, 



77, 872, 873; fruit, 874; leaf, 565, 566, 



567, 572, 587, 588; seed, 906, 907, 908; 



stem, 704. 

 Protective hairs, 567, 572, 573, 574, 575, 



5?6, 577, 578, 623; sheath, 617, 683; 



tissue, 704, 705, 709. 

 Protein, 521, 912, 914, 915; conduction, 



694; grains, 914, 915; synthesis, 528. 

 Proteinoplast, 721. 

 Proteolytic enzym, 616. 

 Protogyny, 835, 836, 853. 

 Protonema, 807. 

 Prunus, gall, 784; shoot, 643. 

 Psedera, leaf variation, 605; leaves, 544; 



pendulous stems, 657 ; tendrils, 652. 

 Pseudoepiphyte, 659. 

 Pseudomixis, 821. 

 Pseudotsuga, 735. 

 Ptelea, crystals, 625; fruit, 921 ; vascular 



bundle, 639. 

 Pteridophytes, asexual reproduction, 814, 



815; reproductive variation, 884 (see 



also Ferns). 

 Puccinia, #73. 

 Pulvinus, 579. 

 Purslane, leaf section, 533. 

 Pycnanthemum, stem section, 702. 

 Pyrenoid, 522, 915. 

 Pyrus, spines, 739. 



Quercus, acorn, 925; cork, 705; galls, 782; 

 habit, 649; leaf variation, 602. 



Raceme, 828, 829, 833, 865. 



Radial bundles, 683; migration, 669, 672; 



symmetry, 489, 629, 630. 

 Radicle, 906, 935. 

 Ranunculus, leaf variation, 590. 

 Raoulia, 73$. 

 Raphe, 906. 

 Raphides, 625. 

 Rattan palm, 656. 



Ray flower, 846; medullary, 684, 685. 

 Reaction, 487, 951; advantageous, 487; 



hydrophyte, 951; mesophyte, 951; 



xerophyte, 951. 

 Recapitulation, 596. 

 Receptacle, 826, 827, 828, 921. 

 Reciprocal parasitism, 752, 786. 

 Regeneration, 733, 748; leaf, 636, 637; 



root, 503. 



Regulation, 487, 951. 

 Reindeer lichen, 611. 

 Rejuvenescence, 597, 601. 

 Releasing factors, 952. 

 Repetition, 597. 

 Reproduction, 505, 636, 637, 667, 805, 806, 



807, 808, 809, 810, 811, 812, 813, 815, 



