246 GLOSSARY 



Gametangium (gamete vessel). The organ which produces gametes. 

 Gamete. A sexual reproductive cell which ordinarily must fuse with 



another gamete in order to live. 

 Gametophyte (gamete plant). The sexual plant in an alternation of 



generations, producing sexual cells or gametes (see Sporophyte). 

 Gemma, plu. gemmm (a bud). An asexual reproductive body, generally 



many celled, rather characteristic of the bryophytes. 

 Generative cell. The cell within the male gametophyte of seed plants 



from which the two sperm nuclei are developed. 

 Genus, plu. genera (a race). The taxonomic group composed of related 



species. 

 Geotropism (earth turning). The action of gravity in directing growth. 

 Gill. A flat spore-bearing plate on the under side of a mushroom or toad- 

 stool. 

 Glume (a husk). A chaffy bract on the inflorescence of grasses. 

 Grain. Such a seed-like fruit as that of the grasses, — a minute, roundish 



body, as a starch grain. 

 Ground tissue. See fundamental tissue. 

 Growing point. The meristematic tip of the root or stem from which 



the tissues are .produced. 

 Guard cell. One of the cells (usually two in number) which serve to 



open and close a stoma. 

 Gymnosperms (naked seeds). Plants (as the Coniferce) which have no 



closed ovaries, so that the seeds are borne naked, usually on scales. 



Halophyte (salt plant). A plant which habitually grows in saline soUs, 



as on sea beaches or in salt marshes. 

 Haustorium (a drawer). A sucker-like absorbing organ of a parasitic 



plant. 

 Heliotropism (sun turning). The action of light in direrting growth. 

 Hermaphrodite. Having both forms of sexual organs together in the 



same structure ; bisexual. 

 Heterocyst (unlike cell). In the blue-green algse a large cell, empty or 



almost empty of protoplasm. 

 Heterogamy (unlike gametes). The condition where the pairing gametes 



are different in form and structure, as the egg and sperm. 

 Heterospory (unlike spores). The condition in which a sporophyte pro- 



duces spores of two sizes, microspores and megaspores. 

 Hilum. The scar on a seed showing its point of attachment to the 



funiculus or the placenta. 

 Holdfast. An organ of attachment developed by certain alg%. 

 Homologous (similar discourse). Of one type, though differing in form 



and function. 

 Homospory (similar spores). The condition in which a sporophyte pro- 

 duces spores of the same size. 

 Hormogonium (chain offspring). A portion of the filament of a blue-green 



alga reproductive in function. 



