GLOSSARY 333 



OOGONIUM : the female, egg-producing organ of Thallophytes. 16. 



OOSPHERE : the female gamete, or egg. 16. 



OOSPORE : the sexual spore resulting from fertilization. 16. 



OVARY : in Angiosperms the bulbous part of the pistil, which contains 



the ovules. 199. 

 OvrLE : the megasporangium of Spermatophytes. 178. 



PAPPUS : the modified calyx of the Composites. 278. 



PARASITE : a plant which obtains food by attacking living plants or ani- 

 mals. 48. 



PENTACYCLIC : applied to a flower whose four floral organs are in five 

 cycles, the stamens being in two cycles. 268. 



PERIANTH : the set of floral leaves when not differentiated into calyx 

 and corolla. 221. 



PERIGYNOUS : applied to a flower whose outer parts arise from a cup 

 surrounding the ovary. 225. 



PETAL : one of the floral leaves which make up the corolla. 221. 



PHOTOSYNTHESIS : the process by which chloroplasts, aided by light, 

 manufacture carbohydrates from carbon dioxide and water. 84. 



PISTIL : the central organ of the flower, composed of one or more car- 

 pels. 200. 



PISTILLATE : applied to flowers with carpels but no stamens. 218. 



POLLEN : the microspores of Spermatophytes. 174. 



POLLEN-TUBE : the tube developed from .the wall of the pollen grain 

 which penetrates to the egg and conducts the male cells. 180. 



POLLINATION : the transfer of pollen from anther to ovule (in Gymno- 

 sperms) or stigma (in Angiosperms). 181. 



POLYPETALOUS : applied to flowers whose petals are free from one an- 

 other. 227. 



PROTHALLIUM : the gametophyte of Ferns. 130. 



PROTONEMA : the thallus portion of the gametophyte of Mosses. 98. 



RADIAL : applied to a body with uniform exposure of surface, and pro- 

 ducing similar organs about a common center. 120. 



RECEPTACLE : in Angiosperms that part of the stem which is more or 

 less modified to support the parts of the flower. 222. 



RHIZOID : a hair-like process developed by the lower plants and by inde- 

 pendent gametophytes to act as a holdfast or absorbing organ, or 

 both. 109. 



SAPROPHYTE : a plant which obtains food from the dead bodies or body 

 products of plants or animals. 48. 



