GLOSSARY 677 



Respiration. — Gaseous exchange \)y which the plant absorbs oxygen and gives off 



carbon dioxide. 

 Respiratory CoeflScient. — The amount of carbon dioxide given off divided by the 



amount of oxygen used in respiration. 

 Salicylic Aldehyde. — An oxidation product of sahcin giving the fragrance to 



meadow-sweet. 

 Somaplasm. — The protoplasm other than the germplasm. 



Sod Culture. — A method of orchard soil management in which a permanent perennial 

 crop is grown between the trees, mowed once or twice during the growing season 

 and then allowed to remain on the ground. A limited area around the trees is 

 hoed, spaded or otherwise tilled. 

 Sod Mulch. — A method of orchard soil management in which a permanent perennial 

 crop is growTi between the trees, mowed once or twice during the growing season 

 and then allowed to remain on the ground. 

 Sporogenous. — Producing spores. 

 Sporophyte. — The plant in the alternating life cycle arising from a fertilized egg and 



producing spores. 

 Sterility. — The inability to produce seeds that will germinate. 

 Supercooling. — Cooling below the freezing point without solidification. 

 Temperature Inversion. — A rise in temperature with increasing distance from the 



ground, up to a certain height. 

 Tetrad. — A group of four cells such as the pollen grains derived from one spore mother 



cell. 

 Torus. — (1) The receptacle of a flower, part of the axis on which the flower parts are 



inserted; (2) the thickening in the center of the membrane in bordered pits. 

 Trimorphism. — Heterogomy, or with long-, short-, and mid-styled flowers. 

 Vacuole.— In cells, the cell sap surrounded by protoplasm. 

 Vanillin. — An aromatic compound, the fragrant constituent of vanilla. 

 Wilting Coefficient. — The percentage of moisture in the soil when permanent wilting 



of plants takes place. 

 Xanthine. — A basic nitrogenous compound related to uric acid; one of the purisen. 

 Xenia. — The direct influence of foreign pollen on the part of the mother plant that 

 develops into endosperm. 



