MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



149 



it is difficult to furnish absolute security against admission of light, 

 and the darkened portion is probably influenced by the illuminated 

 regions near it. 



Phytolacca decandra L. 



A number of strong roots of pokeweed were taken from the soil 

 in a resting condition in November and placed in pots in the control 

 house, and dark room immediately. Growth 

 began about a month later. The shoots pro- 

 duced in the dark chamber elongated much 

 more rapidly than those under normal illu- 

 mination and had attained a length of 22 cm. 

 on January 22, 1902. Shortly afterward 

 these shoots perished and others sprang up 

 from the crown, which likewise made only a 

 limited growth. This process was repeated, 

 and on April 27 four etiolated shoots were to 

 be seen with others beginning to develop. 

 On July 6th the stems had reached a length of 

 42 cm., with leaves 45 cm. long. The tuber- 

 ous underground storage organ remained 

 intact and seemed sound and healthy. 



The diameter of etiolated stems did not 

 exceed 11 mm., which is much less than the 

 normal. The cross section was ovoid in 

 outline although lacking the small irregular- 

 ities of that of the normal stem. The etio- 

 lated leaves consisted of a small slightly 

 elongated petiole curved upward from a 

 horizontal position with a much reduced lam- 

 ina. The entire leaf was a rich yellow 

 color. 



The pith showed the transverse splittings of the normal stem in 

 the basal portion, but in the terminal portion a long continuous cavity 

 occupied the center of the stem. The epidermis was not excessively 

 elongated and had comparatively thin walls. The prestomatal cells 

 were to be seen richly loaded with granular matter and plastids and 

 in some instances the first division had taken place. The collen- 

 chyma was fairly well developed in the angular portions of the stem 

 occupying about six or seven la3'ers, in some instances and but two 



Fig. 108. Etiolated stem 

 of Phytolacca decandra. 



