MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



197 



development of the medullary and intravascular parenchyma as in 

 etiolated stems of F. Americana. 



Ibervillea Sonorae Greene. 



A number of large woody tubers of " guarequi " were collected 

 from the sandy plains around Torres, Sonora, Mexico, in February, 

 1902. Some were placed in the control house and others in the dark 

 room in May, 1902. 



Adventitious buds on the upper surfaces of the irregular tubers 

 soon began activity, sending up vines 3 meters in height and climb- 

 ing by means of extra-axillary tendrils after the manner of the 

 Cucurbitaceae. These 

 tendrils were extremely 

 sensitive and reached a 

 length of about 6 cm. 

 The internodes of the 

 glabrous normal stems 

 were about 6 to 8 cm. 

 in length, and the peti- 

 oles about 4 or 5 cm. 



Etiolated stems did 

 not reach a length in 

 excess of 50 cm., a 

 limited growth perhaps 

 partially due to the 

 high humidity of the 

 dark room. The plant 

 is found to flourish best 

 under the same con- 

 ditions as subtropical 

 cacti from the most 

 arid regions of Amer- 

 ica. The internodes of 

 the etiolated stems were 

 fairly normal in length, ^,^ ,,. tvt iu u ^ 77 •?, c 



J ' Fig. 153. Normal branches of Ihervtllea Sonorae. 



except the basal ones 



which were much elongated, but were about double the thick- 

 ness of green stems. Etiolated petioles were about a half longer 

 than the normal. Tendrils were present, but did not attain the 



