The root-tubers of [sopyrum occidentale. 
D. T. MAC DOUGAL. 
Soon after my recent paper dealing with the physiology of 
the tubers of Isopyrum biternatum? had passed into the hands 
of the printer, I received a number of living plants of J. occt- 
dentale H. & A. from California, and the root-tubers were 
found to exhibit such marked characteristics that a special 
he structure of the root, which differs in many importan, 
features from that of 7 biternatum, may be best understoo 
by following its developmental history, which is in the earlier 
stages similar to that of Ranunculus vepens.* The stele 1 
sencrentiated while the cortex is quite similar to that 0 | 
biternatum, already described. In the thickening © ‘ally 
roots into tubers the medullary rays are developed inter 
“ernatul 
*A contribution to the physiol f th t-tubers of Isopyrum ape 6 
Torr. and Gray. oi won sige ho ager? Stud. 1: 5075! 
pi th aidig t Paperate, March 31, 1896. Minn. Bot. 
Greene, Flora Franciscana tim. 308. 1892 
*Vines, Text Book of Botany 16e fe. 127. Tes. 
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