58 MISSOURI BOTANICAL GARDEN. 



preceding rather than the present species, the latter 

 is doubtless now in cultivation under that name. * 



For some reason this very striking Yucca does not ap- 

 pear to have been collected or commented on by the bota- 

 nists of the original boundary survey, though it is 

 abundant in the Rio Grande valley about Presidio. The 

 botanists of the later survey seem to have passed in by for 

 Y. glauca, which I have not seen from so far south. 



33. Inflorescence racemose or branched close to the leaves. Sub- 

 acaulescent plants. 



Y. angustissima Engelmann, in herb. 



Y. glauca Coville, Contr. U. S. Natl. Herb. 4 : 202. 



Y. radiosa Coville, 1. c. 203, 277. 



Y. elata ? Merriam, N. A. Fauna. 7: 358. 



Acaulescent, from thick horizontal root-stocks. Leaves as in the 

 narrowest forms of Y. radiosa and Y. glauca, 2 to 5 mm. wide, .2 to .4 m. 

 long, pungent, white-bordered, very freely and often curly-filiferous 

 below. Inflorescence glabrous, 1 to 1.5 m. high, racemose, or short- 

 branched below. Perianth segments rather short, mostly acutely lan- 

 ceolate : style as in the preceding. Capsule scarcely exceeding 50 mm. in 

 length, rough, brown, constricted, with a median rib on each valve : seeds 

 glossy, 5 to 7 X 7 to 8 mm. Plates 23, f.l.24,f.l. 83, f. 6. 



Southwestern Utah, southeastern Nevada, and north- 

 western Arizona, in the region of the Colorado river. 

 Plate 93, f. 1. 



In habit, this species, which is briefly referred to without 

 name by Professor Sargent, f recalls the narrow-leaved form 

 of Y. glauca as found, for example, about Albuquerque, 

 N. M., or the narrowest-leaved forms of Y. radiosa, when 

 the latter is acaulescent. From the former it differs in its 

 more frequently branched inflorescence, oblong (white ?) 

 style, and smaller capsule and seed ; and from the latter in 

 never becoming a tree and in its subsimple inflorescence, 

 smaller, rougher and darker, constricted capsules, and muck 



* See Baker, Kew. Bull. 1892 : 8. 

 t Sargent, Silva. 10 : 28. Note. 



