GLOSSARY 



419 



sporangium a spore case; a structure in which spores are 

 formed. 



spore (1) the true spore often is Hmited to a plant bud; 

 often designated bisexual, male, or female in reference 

 to the sexuality of the gametophyte it produces; (2) a 

 resting cell or life-cycle stage generally within a pro- 

 tective covering, e.g., a cyst; (3) asexual spore, a repro- 

 ductive cell produced by mitosis; (4) sexual spore, a 

 reproductive cell produced by meiosis, includes a true 

 spore. 



sporocorp a multicellular, spore-forming body, often nut- 

 like. 



sporophyte specifically, the spore-forming adult stage in a 

 diplobiontic life cycle; loosely, any spore-forming 

 plant. 



sporulation asexual reproduction in plants, generally by 

 meiosis in which a single cell (a true bud called a 

 spore) is the reproductive body formed. 



stamen a flower organ distinctive in containing male 

 spore-forming organs; consisting of anther and fila- 

 ment. 



stand a recognizable unit of plant species, somewhat uni- 

 form in composition, appearance, and habitat condi- 

 tions. 



statoblast an internal (generally multicellular) bud formed 

 by ectoprocts. 



stele a vein of vascular plants. 



stem (1 ) the axis of a plant consisting of nodes and inter- 

 nodes; (2) a stalk in various, mostly sessile, animals; 

 (3) pertaining to the ancestor of a very large group of 

 organisms. 



steppe a dry grassland in which plant aerial parts often 

 die back and underground parts enter dormancy dur- 

 ing part of the year; also, the climate or soil of such an 

 area. 



sterile pertaining to an organism or part of an organism 

 without functional reproductive structures; pertaining 

 to an area devoid of life, particularly microorganisms. 



stigma the apical portion of a pistil, which receives pollen 

 and upon which pollen germinates. 



stimulus an external or internal change in an organism's 

 environment capable of inducing a reaction by the 

 organism. 



stipe a stalk, generally short and supporting in function. 



stipule a small, leaflike appendage that may occur on 

 either side of the base of a leaf 



stock in geology, an irregular igneous rock mass of roughly 

 conical or cylindrical shape up to 40 square miles in 

 surface area; formed by subsurface intrusion and 

 solidification of magma ; see batholith. 



stolon a plant stem or animal stemlike structure that 

 periodically by budding gives rise to new individuals; 

 generally, a structure growing horizontally to and 

 upon a substrate. 



stoma a minute space between two specialized cells (guard 

 cells) in the epidermis of plants. 



strand the ocean shore above the highest tide level but 

 subject to sea wind, sand blasts, and salt spray. 



stratum any layer or bed of air, water, rock, organisms, 

 and so on. 



strike in geology, the compass direction of an imaginary 

 line formed by intersection of a layer of rocks with the 

 horizontal plane at the surface of the earth; by defini- 

 tion, strike is measured perpendicular to the dip; 

 approximately the direction of an observed surface out- 

 crop of a rock layer; see Figure 4.23, p. 62. 



style the part of a flower's pistil between stigma and 

 ovary. 



subdominant species any species in a community other than 

 a dominant; a subordinate species. 



subordinate species a subdominant. 



subsidence sinking, generally of a large part, of the earth's 

 crust. 



subsoil the part of a soil profile below the true soil and 

 above weathered bedrock that is occupied by little or 

 no roots or organic material. 



subspecies a subunit of a species of variable status, but 

 generally recognized by at least one unique feature or a 

 unique combination of features; often it is the only 

 occupant of a particular area by a species; it may or 

 may not be isolated from like species subunits. 



substrate the foundation, substance, or base upon which 

 any object spreads, lies, grows, attaches, or moves; in 

 organisms also includes such things as their nutrients. 



succession the development of equilibrium conditions in 

 living or nonliving things by means of a sequence of 

 recognized stages that terminate — theoretically, and 

 often actually — in equilibrium conditions; generally 

 restricted to organism, especially plant succession. 



superorganism a community in the sense of its collecting 

 organisms and functioning much like an organism or 

 something greater than an organism. 



swamp a semiaquatic habitat having woody plants, trees, 

 and/or shrubs. 



sweepstake route an accidental highway in that organ- 

 isms (probably by chance) are transported from one 

 area to another; e.g., often an ocean region in reference 

 to land organisms. 



symbiosis the living together of organisms, usually two or 

 more species; degree of permanence generally is not 

 implied, but temporary symbiosis usually must involve 

 a significant relationship. 



syncllne a downward arcing or folding of rock layers. 



synergism the total activity of various parts, producing an 

 effect greater than the sum of the activities of individ- 

 ual parts. 



tactile pertaining to the sense of touch. 



tadpole a frog or ascidian larva of general fishlike form. 



