ON THE BEHAVIOR OF AN EXCISED BRANCH OF 



THE SAHUARO 



RAYMOND J. POOL 

 The University of Nebraska, Lincoln, Nebraska 



Large individuals of the giant cactus or Sahuaro, Carnegiea 

 gigantea, have been removed from time to time from their desert 

 home to various institutions and other places in the United States 

 where they have continued to grow and bloom almost normally 

 from year to year. The specimens at the New York Botanical 

 Garden have been notably successful considering the changed re- 

 lations which at best can scarcely approach the environic condi- 

 tions which prevail within the natural range and habitat of this 

 Papago-land xerophyte. 



A curious but well known feature of these gigantic water-storage 

 stems is seen in their ability to withstand desiccation and to pro- 

 duce flowers even though the greater bulk of the plant body may 

 have been killed. MacDougal and the members of the staff at 

 the Desert Laboratory have conducted extensive and intensive 

 investigations upon the behavior of uprooted plants and of ex- 

 cised portions of the Sahuaro as well as of many other cacti and 

 cactus associates. The ''w^ater-balance" of desert plants is a 

 problem to which MacDougal has directed his attention for 

 several years in connection with the numerous projects which 

 are constantly under investigation by the Department of Bo- 

 tanical Research of the Carnegie Institution. In 1908 this 

 writer called attention^ to the fact that decay sometimes begins 

 in the lower part of the main stem of the giant cactus and slowly 

 proceeds upward. The fleshy cortex and pith of the main trunk 

 go to pieces first and thus expose the rod-like units of the woody 

 cylinder. In spite of the fact that the lower part of the stem is 

 dead the upper branches may retain their normal form and color 



1 Across Papagueria. Plant World 11: 93-99, 1908. 



17 



THE PLANT WORLD, VOL. 19, NO. !, 1916 



