112 MISSOURI BOTANICAL GARDEN. 



the name Y. Mohavensis, and followed the conclusions 

 then reached in his subsequent treatment in the Silva * of 

 the two forms, the Yucca macrocarpa in both instances 

 being the tree which occurs about Sierra Blanca with the 

 true Y. macrocarpa but possesses a gamophyllous perianth 

 and is here treated as one of the types of the genus 

 Samuela . 



Though leaves resembling those of Y. baccata have occa- 

 sionally been brought in from the general vicinity of El 

 Paso, Texas, and the adjacent parts of New Mexico, out of 

 the range of Y. baccata, together with some photographs 

 showing a tree-like growth, and flowers of smaller size than 

 those of Y. baccata, the absence of herbarium material rep- 

 resenting the original collections of Y. baccata macro- 

 carpa indicated the desirability of making collections of all 

 of the arborescent Yuccas of the great bend of the Eio 

 Grande, and for this purpose, in August, 1900, I drove 

 from Marfa, on the Southern Pacific railroad, to Presidio, 

 on the river, finding at intervals the plant of El Paso and 

 New Mexico, and, in sandy places, Y. radiosa (which 

 seems not to have been noted by the boundary botanists), 

 but, rather unexpectedly, no trace of the Sierra Blanca 

 tree figured by Professor Sargent as Y. macrocarpa. The 

 latter, then, may be eliminated as certainly not the plant 

 to which the name macrocarpa was applied by Dr. Torrey, 

 though the latter also occurs at Sierra Blanca. 



Yucca macrocarpa, as it occurs in the vicinity of Presidio 

 and thence in general west to south-central Arizona and 

 north to Las Cruces, when seen from a distance resembles 

 considerably Y. Treculeana, though usually of a yellower- 

 green foliage than that species. The trunk very rarely 

 branches, and is usually 2 or 3 m. high, though occasional 

 specimens are seen exceeding 5 meters. Its concave stiff 

 leaves are usually .6 or .9 m. long and about 40 mm. wide, 

 though sometimes reaching a length of over a meter, and, 



* Silva. 10: 13. pi. 499. 15. pi. 500. 



