GLOSSARY 501 



Receptacle. — The end of a floral stem to which the calyx and corolla are 



attached. 

 Resin. — The raw sap of the longleaf pine. 

 Respiration. — ^The oxidation of carbon compounds in the cell, as a part 



of metabolism, necessary for the liberation of the energy in food. 

 Rhizoid. — The filamentous absorbing structures of thallus plants and 



mosses. 

 Rhizome. — An underground creeping stem from which arise flowers and 



leaves. 

 Root hair. — Outgrowth of an epidermal cell of the root, specializing 



in absorption of water and dissolved minerals. 

 Rosin. — The hard residue left after distilling turpentine from resin. 



Saprophyte. — ^A heterotrophic organism depending upon dead organic 



material for food. 

 Saprophytic. — Deriving organic materials from remains or products of 



organisms (see saprophyte). 

 Saw logs. — Logs of sufficient size to be sawed into lumber. 

 Sawtimber. — Trees, or timber of large enough size to be made into saw 



logs. 

 Sapwood. — The outer cylinder of the tree's woody stem, immediately 



surrounding the heartwood and gradually changing into it as growth 



progresses. 

 Sclerotium. — A mass of very heavy-walled hyphae, capable of with- 

 standing cold and drought. 

 Sclerenchyma. — Highly specialized supporting tissue, represented by the 



fibers of hardwoods. 

 Seed. — The ripened ovule containing the embryo and stored food. 

 Sepal. — One of the green parts of the flower (see calyx) whose function 



is to support and protect the corolla. 

 Shelter belt. — ^A belt-like planting of trees, placed at right angles to the 



prevailing winds for the purpose of protecting fields or homes. 

 Simple leaf. — A leaf composed of a single blade, in contrast with the 



condition found in compound leaves (q.v.); example, elm or violet. 

 Slash. — ^The debris — tops, limbs, etc.— left after felling and removing 



timber from the forest. 

 Spathe. — ^A showy leaf, or bract, occurring below the fleshy floral axis 



of members of the Arum Family; example, calla lily. 

 Species. — ^The smallest classification unit: a group of related individuals 



which are able to breed with each other. 

 Sperm. — The motile male gamete produced during sexual reproduction. 

 Spirillum. — A spiral or corkscrew-shaped bacterial cell. 

 Sporangium. — A structure in which spores are produced. 



