356 INTRODUCTION TO BOTANY 



Stamen. The microsporophyll in spermatophytes. 



Stigma. That portion of the surface of a pistil (without epidermis) 

 which receives the pollen. 



Stigmatic. Relating to the stigma, or stigma-like. 



Stoma (a mouth) ; pi. stomata. Epidermal structures which serve for 

 facilitating gaseous interchanges with the external air, and for transpi- 

 ration of moisture. They are often incorrectly called " breathing pores." 



Strobilus. A cone-like cluster of sporophylls. 



Style. The usually attenuated portion of the pistil which bears the 

 stigma. 



Succulent. Thick and fleshy. 



Suspensor. A chain of cells which develops early from the oospore, 

 and serves to push the embryo cell deep within the embryo sac. 



Symbiont. One of the organisms that has entered into a symbiotic 

 relationship. 



Symbiosis (living together). Applied to a condition in which two or 

 more organisms are living in an intimate relationship. 



Sympetalous. Having the petals apparently all united, as if grown 

 together by their edges. 



Syncarpous (carpels united). Applied to those conditions in which 

 the carpels have united into a compound pistil. 



Synergids (helpers). The two nucleated bodies which accompany the 

 oosphere in the embryo sac, and together with it form the egg apparatus. 



Testa (a shell). The outer seed coat. 



Tetracyclic (four cycles). Applied to those flowers in which there are 

 four cycles of floral organs. 



Tetradynamous (four strong). Said of a stamen cluster in which there 

 are four long and two shorter stamens. 



Thalloid. Thallus-like. 



Thallus (a young shoot). The body of lower plants, which exhibits 

 no differentiation of stem, leaf, and root. 



Tissue. A texture built up of mutually dependent cells of similar 

 origin and character, as the cambium layer. 



Tracheid. A long, slender cell, with closed ends and its walls thick- 

 ened after the cell has attained its full size, as in the pitted cells of 

 coniferous wood. 



Transpiration. The loss of water derived from the interior of the 

 plant body in the form of vapor. The term is not generally used with 

 reference to plants of low organization. 



Trichome (a hair). A general name for a slender outgrowth from the 

 epidermis, usually arising from a single cell. 



Turgidity. The normal swollen condition of active cells which results 

 from the distension brought about by absorption of water. 



