ROOT VARIATION IN DESERT PLANTS 



341 



caused to grow in glass or metal tubes of various sizes, with the 

 follow ng results. 



Jatropha cardiophylla, which in nature has fleshy roots that 

 lie within 5 cm. of the surface, was induced to send roots to a 

 depth of 43 cm. 



Fouquieria splendens has a root-system, which in a measure, is 

 intermediate between that of Franseria and that of the cacti. 

 The roots usually penetrate less than 37.5 cm., but in tubes 

 transplanted specimens were seen to send roots as deeply as 1.1 

 m. Seedlings of the species, 7 months old, formed a main root 

 47 cm. long. 



Opuntia arbuscula, whose anchoring roots usually attain a depth 

 of less than 30 cm. and whose absorbing roots lie as near the 

 surface as 1.5 cm., formed roots, in glass tubes, 1.21 m. in length. 

 The roots of 0. versicolor, which also are usually shallowly placed, 

 formed a main root 78 cm. long. 



