Chapter 10 

 PLANT GROWTH^ 



by Kenneth V. TJwnann 



In this chapter an attempt will be made to present as a whole the study of plant 

 growth, principally that of higher plants, with primary emphasis on experimental 

 analysis, and on the study of growth at the cellular and biochemical levels. De- 

 scriptive treatments of growth phenomena, especially in higher plants, may be 

 fovmd in many of the older German textbooks such as Goebel, Jost and Stras- 

 burger, who have presented extensive observations of great numbers of plant 

 types. In recent times, many of the anatomical aspects of growth have been well 

 treated in Esau's Plant Anatomy (1953); the Symposium on the Growth of 

 Leaves (Milthorpe, ed., 1957) is also valuable. 



Much of the subject, especially that concerned with the action of auxin on 

 growth, has been reviewed more than once. The books of Went and Thimann 

 (1937), Thimann et al. (1952), Soding (1952), Audus (1953), Leopold (1955) and 

 Thimann (1956a) as well as the Symposia held at Wisconsin (Skoog, ed., 1951) 

 Brookhaven (1953) and Wye (Wain and Wightman, ed., 1956) give extensive 

 coverage and bibliographies. A number of reviews are also referred to in the 

 text. Because of these publications, references to individual papers will only be 

 made if their contents are discussed in detail or their data presented, or if for one 

 reason or another they have been inadequately treated in the reviews and books. 

 Papers of the last few years, especially of 1950 and later, will, of course, be cited 

 freely. It must be made clear, however, that the aim has been to present a broad 

 and balanced picture rather than a detailed bibliographic reference. 



I. GENERAL CHARACTERISTICS OF PLANT GROWTH 



The pattern of growth of plants differs from that of animals in four important 

 respects. 



In the first place, both for higher (flowering plants) and lower plants (ferns, 

 mosses, fungi and algae) growth is typically indefinite. The plant body continues to 



^ Support of the author's researches, over a period of years, by the Committee on Growth, 

 acting for the American Cancer Society, and by the National Science Foundation, is grate- 

 fully acknowledged. 



I wish to thank Dr. Bruce B. Stowe for valued criticism of the manuscript. 



