520 GLOSSARY 



Parasite, an organism living upon or within another living organism (host) 



and obtaining its nutriment from the host, 134-137. 



Parenchyma (Pa-ren'-chy-ma), fundamental tissue, soft tissue with thin- 

 walled cells, in the fern, and seed plants, 37, 59, 91. 



Pentamerous (Pen-tam'-er-ous), said of flowers with their parts in fives, 407. 

 Pepo, a fruit like the squash where the receptacle is united with the ovary 



and forms the outer portion of the fruit, 213. 

 Perennial, living for many seasons, 43, 68. 

 Perfect, in flowers, those which have both stamens and pistils; in fungi 



applied to the final form or stage in the life cycle (teleutospore, ascus 



stage, basidium stage, etc.), 145, 156, 288, 291. 



Perianth, the corolla and calyx of the flower (particularly in Monocotyle- 

 dons), 180, 406. 

 Pericarp (Per'-i-carp) , the mature wall of the ovary, particularly in fruits, 



13, 19, 205, 206, 209. 

 Pericycle (Per'-i-cy-cle), the specialized layer of cells surrounding the 



fibrovascular bundles of the stem and separating them from the 



cortex, 36. 

 Perigynous (Per-ig'-y-nous), said of the stamens or petals when they are 



borne on the edge of the more or less elevated calyx- tube, 147. 

 Perisperm (Per'-i-sperm) , a portion of the interior of the ovule rich in 



plant food which lies next to the endosperm or embryo in certain seeds 



(nucellus tissue), 202, 203, 415, 416. 

 Perithecium (Per-i-the'-ci-um, plural, perithecia), the fruit body of the 



Ascomycetes where the wall entirely surrounds the group of asci or 



opens by a pore, 287, 280, 293. 

 Petal, a member of the series of parts of a flower making up the corolla, 



143, 152, 155, 158, 162, 164, 168, 180. 



Phloem (Phlo'-em), the bast portion of the fibrovascular bundles, 37. 

 Photosynthesis (Pho-to-syn'-the-sis), the process in the formation of sugar 



and starch in leaves from carbonic acid through the action of sunlight 



and chlorophyll, 97, 104-113. 



Photosynthetic (Pho-to-syn-thet'-ic), the character or property of photo- 

 synthesis, as photosynthetic assimilation, 113. 

 Phycophaein (Phy-co-phae'-in) , algal brown, the brownish pigment of the 



Phaeophyceae (Brown Algae), 258. 

 Phylloclade (Phyl'-lo-clade), a more or less flattened green branch of the 



stem, often leaf like, literally a "leaf stem," 52, 53. 

 Phyllotaxy (Phyl'-lo-tax-y), the arrangement of leaves on the stem, 75. 

 Phylogeny (Phy-log'-en-y), the study of the evolution of organisms in 



time, from lower to higher, etc., 487. 



Pileus (Pil'-e-us), a cap, applied to the cap of a mushroom, 323. 

 Pinna (Pm'-na), a leaflet, 80, 87, 88. 



