n^K^m^mts 



A. Riddellia cooperi, from sandy loam east of West Wash, showing the large num- 

 ber of slender laterals arising from crown of tap-root and the branching feature of 

 the bases of the main laterals. B. Riddellia from red claj^ soil near West Wash, to 

 illustrate lack of slender roots at crown of tap-root. 



C. Dasylirion texanum, from bajada near Rincon mountains, with root-system 

 partly exposed. 



D. Shoot and root habit of Yucca sp., from bajada near Rincons. Plant supported 

 by two props, one at side and one below, which should not be mistaken for roots. 



E. Root character of Yucca radiosa from bajada near the Rincons. 



