ROOT-SYSTEMS OF PEKEXXIALS. 



63 



The othor woody plants growing near I-'oiiguiciia were mainly Covillca 

 iiidcntala. and an occasional specimen of ParkiiiiOHiii intcrophyUa. 



Two specimens of Fouquicria were specially studied, of which one was 

 young and the other mature. The younger plant had a shoot 24 cm. high, 

 which had a central main axis and two branches 3 cm. and 15 cm. long. 

 The habit of the plant is well shown in fig. 7. 



The roots of Fouquicria splcndciis are coarse and brittle, and bear rela- 

 tively few branches. The tap root was large and penetrated the ground 

 8 cm., where it forked, one branch extending horizontally 13 cm. and the 

 other going down 18 cm. before branching. Each of the main forks of the 

 main root branched onlv two or three times. 



Fio. 8, — HorizonUiI extension of the root-system of Foiiqitieria splciijeus from the bajada at 

 the north base f)f Tumamoc Hill. Dots represent position of CoviUea tridenlata. \\hii:h 

 occurred within the root-area of FuuquUria, and dotted lines such roots of CoviUea as 

 were found on the same horizon as the Fottqiiieria roots. 



Above the forking of the tap root, about 3 to 4 cm. from the surface of 

 the ground, two laterals arose, which, as far as traced, ran in a nearlv hori- 

 zontal direction. One of these bore 3 branches and was over 22 cm. long. 

 At the base the laterals were less than i cm. in diameter, and, where broken 

 off, they were slightly more than i mm. in diameter. Thus the roots of 

 Fouquicria are so heavy that they may perhaps be termed fleshy. 



