GLOSSARY OF TERMS USED IX THIS BOOK. 359 



Pleiochasium, an inflorescence where each relative or false axis produces 



more than two branches, 228. 



Pneumatophore, term applied to special organs of aeration, 327. 

 Pollination, the passage of the pollen from the stamens to the stigma of the 



pistil, 192, 205, 241, etc. 

 Pome, the fruit of the apple, 230. 



Poricidal, said of capsules which dehisce by a terminal pore, 230. 

 Progeotropism, a txirning toward the earth, said of roots which grow toward 



the earth, 108. 

 Prothallium, the sexual stage of the pteridophy tes, gymnosperms, and angio- 



sperms, 166, 170, 203-207. 

 Protonema, thread-like growth proceeding from the germinating spore of 



bryophytes, and some pteridophy tes, 169. 



Protoplasm, the living substance of plants and animals, 1527. 

 Pyxidium, pyxis, a capsule which opens with a lid, 230. 

 Raphe, the part of the stalk of the ovule which is joined to the ovule where 



the ovule is bent upon its stalk, 207, 210. 

 Respiration, an interchange of gases by the plant during growth, by which 



oxygen is consumed and carbon dioxide is liberated, 94-101. 

 Rhizome, an underground root-stock, 200. 

 Runners, prostrate stems which take root here and there, 219. 

 Samara, a winged seed, 256. 

 Schizocarp. a dry several- loculed fruit in which the carpels separate from 



each other at maturity but do not dehisce, 230. 

 Septicidal, applied to a syncarpous capsule in which the carpels separate 



along the line of their union, 230. 



Silique, a capsule of two carpels which separate at maturity, leaving the par- 

 tition wall persistent, 230. 



Spadiz, a spike in which the main axis is fleshy, 227. 

 Sperma'.ozoid, a motile sperm cell, 122, 123, 142, 171, 172. 

 Sperm cell, the male cell which contains the nucleus for union with the egg 



nucleus; it may be motile or non-motile, 204, 205. 

 Spike, an inflorescence with a long main axis, and with sessile flowers on it 



or on very short lateral axes, 227. 



Spikelet, a short lateral flower-branch in the grasses, 247, 249. 

 Sporangium, a spore case containing spores. 

 Sporogonium, the entire structure which is the product of the fertilized egg 



in the bryophytes, 144, 145, 152. 

 Sporophyll, term applied to leaves in the pteridophytes, gymnosperms, and 



angiosperms which bear sporangia, 176, 188, 197. 



Stamens, the members of the flower which bear the pollen grains or micro- 

 spores, 201, 203, 206. 



