113 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 Rio 
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. pl. 499. 15. pl. 500. 
