GLOSSARY 521 



Pistil, the member of the flower which contains the ovule, 143, 152, 153, 



156, 160, 163, 165, 171, 177, 181, 186, 190, 192. 



Pistillate, said of flowers which have pistils but no stamens, 176, 179, 399. 

 Pith rays, medullary rays, 66. 



Placenta, the part of an ovary where the ovules are attached, 144, 145. 

 Plankton, the wandering life of the sea, particularly the minute forms of 



plant and animal life in the sea or in bodies of water, 256. 

 Plasmolysis (Plas-mol'-y-sis), the shrinking or collapsing of the proto- 

 plasm away from the cell wall, 234, 235. 

 Plumule, the bud at the apex of seedlings, 7, 8, 12, 13. 

 Pollinium (Pol-lin'-i-um) , a compact mass of pollen grains as in the orchids 



and milkweeds, 183, 189, 193. 

 Polygamous (Po-lyg'-a-mous), where both perfect and imperfect flowers 



occur on the same plant, 146. 

 Polymorphic (Pol-y-morph'-ic), having several forms, in botany applied to 



fungi and algae which have two or more stages in the complete life cycle, 



273, 287. 

 Polype talous (Pol-y-pet'-al-ous), a flower in which the petals are not 



united, 147. 

 Pome, a fleshy fruit in which the inner layer of the pericarp becomes papery, 



and forms the "core" as in the apple, 213. 



Procarp (Pro'-carp), the female branch or organ in the red algae, 261, 262. 

 Promycelium (Pro-my-ce'-li-um, plural, promycelia), the germ tube devel- 

 oped in the germination of the teleutospore of the smuts and rusts, 



305, 314, 318, 320. 

 Protease, an enzyme formed by certain plants which dissolves protein 



substances, 133. 



Protein (Pro'-te-in) , a nitrogenous food substance, 20, 24, 114. 

 Proterandry (Pro-ter-an'-dry), condition of flowers where the stamens 



mature before the stigma, 191. 

 Proterogynous (Pro-ter-og'-y-nous), said of flowers in which the stigma 



matures before the stamens. 

 Proterogyny (Pro-ter-og'-y-ny), condition of flowers in which the stigma 



matures before the stamens, 407, 419. 

 Pro thallium (Pro-thal'-li-um), the thallus generation, or gametophyte of 



ferns and seed plants, 359, 364, 368, 371, 372, 375, 376, 379, 395, 398, 



400, 402, 410. 

 Protonema (Pro-to-ne'-ma) , first thread, the thread-like growth formed on 



the germination of the spores of mosses and ferns, 346, 350, 351. 

 Protoplasm. (Prg'-to-plasm), the living substance of plants and animals, 3, 



4, 5, 14, 39, 40, 233-237, 249, 277. 

 Pteridophyta (Pter-i-doph'-y-ta), or Pter'-id-o-phytes; branch of the Plant 



Kingdom including the ferns, horsetails, club-mosses, etc., 225, 229. 



