GLOSSARY 435 



Endothecium. In bryophytes, the central mass of cells developed in the young sporo- 

 phyte; in an anther, a specialized layer of cells lying beneath the epidermis and 

 assisting in dehiscence. 



Epidermis. A superficial layer of cells on leaves, young stems and roots, etc. 



Epigynous. Said of flowers whose ovary is sunken in the receptacle so that the peri- 

 anth seems to arise from its summit. 



Epiphyte, k plant that grows upon another plant, but not parasitically. 



Eusporangiate. A type of sporangial development occurring in spermatophytes and 

 most pteridophytes in which the sporogenous tissue arises from the inner segment 

 of the initial cell. 



Exarch. Development of primary xylem in a centripetal direction. 



Excurrent. Having a prolonged main stem extending to the top, as in some trees. 



Exine. The outer layer of the cell wall of a pollen grain. 



Eyespot. An eye-like spot of pigment in certain motile unicellular algae and repro- 

 ductive cells. 



Fertilization. The fusion of a sperm and an egg or of a male nucleus and a female 

 nucleus to form a new individual (zygote). 



Fiber. A thread or thread-like structure; a long, slender, thick-walled cell, as in 

 sclerenchyma. 



Filament. A thread-like series of cells or a very long, cylindrical, single cell, as in cer- 

 tain algae and fungi; the part of the stamen that supports the anther. 



Fission. Reproduction of a unicellular plant by division into two equal cells. 



Flagellum. A long, whip-like, protoplasmic process or appendage of a cell capable of 

 lashing movement. 



Flower. In angiosperms, a group of sporophylls usually surrounded by a perianth. 



Foliar. Pertaining to, or consisting of, leaves. 



Foot. The basal portion of the sporophyte in mosses and most liverworts; a part of 

 the embryo of pteridophytes that is embedded in the gametophyte and acts as an 

 absorbing organ. 



Fruit. In angiosperms, a ripened ovary with any external parts that ripen in associa- 

 tion with it. 



Fucoxanthin. A brown pigment associated with chlorophyll in the brown algae. 



Funiculus. The stalk of an ovule. 



Fusion nucleus. The nucleus, in an embryo sac, typically formed by the union of two 

 polar nuclei. 



Gametangium. A cell or organ in which gametes are formed; a sex organ. 

 Gamete. A mature sex cell; a cell capable of uniting with another of opposite sex to 



form a zygote. 

 Gametophore. A branch bearing sex organs or gametangia, as in mosses. 

 Gametophyte. In plants with an alternation of generations, the individual that bears 



gametes and has the haploid number of chromosomes. 

 Gemma. A detachable bud or bud-like body capable of developing into a new plant, 



as in bryophytes and pteridophytes. 

 Generative cell. In gymnosperms, the cell in the pollen grain that gives rise to the 



stalk and body cells, in angiosperms to the two male cells. 

 Gill. One of the plates on the under surface of the pileus of a mushroom. 

 Gleba. The inner portion of the basidiocarp in the Gasteromycetales. 

 Glycogen. A carbohydrate related to starch and dextrin, very common in animal 



tissues. 



