78 PLANT GROWTH 



insect. Many others might be mentioned. Some of the 

 desert plants, as cactus, have the leaves reduced to small 

 spines. 



REFERENCES 



Brown, W. H., The Plant Kingdom, Ginn and Co., 1935. 



Hill, J. B., L. 0. Overholts, and H. W. Popp, Botany, McGraw-Hill Book Co., 1936. 

 Turrell, F. M., "The Area of the Internal Exposed Surface of Dicotyledon Leaves," 

 American Journal of Botany, vol. 23, pp. 255-264, 1936. 



