56 THE PLANT WORLD. 



THE ARTIFICIAL IXDUCTIOX OF LEAF FORMA- 

 TION IX THE OCOTILLO* 



By Francis E. Lloyd, 



The post-pluvial appearance of foliage within a very short time 

 upon desert plants which remain through periods of drought in 

 a leafless condition is a phenomenon which has very often been 

 remarked. The behavior in this regard is most striking in deserts, 

 where there is prolonged lack of rain. Although in some regions 

 the rain penetrates into the grouiid ver}- rapidly, nevertheless it 

 has seemed im|)robable to many, no doubt, that the absorption 



Fig. 8. Fouquicria splriidciis. showing a branch which had been irri- 

 gated during four days. 



of this water from the soil alone gives the necessary stimulus to 



leaf formation. Led by this idea, attempts have been made to 



find in man\- of the superficial structures of plants the means for 



the absorption of water, or water vapor, and it may very well be 



that experimental research will in the future throw light upon the 



* This work was done at the Desert Botanical Laboratory, Tucson, 

 Arizona, under a grant from the Carnegie Institution, of Washington, 

 during the summer of 1905. Reprinted from TDirrya. Vol. 5. No. 10. 

 Oct., 1905. 



