ENDOGENOUS SERIES. 195 



Joshua-tree, Yucca. -i Y ? cca arborescens Torr. 

 ( Yucca brevifolia Engelm. 

 Nomenclature. (Sudworth.) 



Joshua-tree, The Joshua, Yucca Cactus (Cal.). 



Yucca, Yucca Tree (Utah 

 Ariz., N. M., Cal.). 



Locality. 



Central and lower Rocky Mountain region. 

 Features of Tree. 



Twenty-five to forty feet in height, six inches to two feet in 

 diameter. 



Thick outer cover or bark.* 

 Color, Appearance, or Grain of Wood. 



Light brown to white, porous grain, interlaced fibre structure. 

 Structural Qualities of Wood. 



Light, soft, spongy, flexible in thin sheets, such as are devel- 

 oped by the rotary cut. 



Representative Uses of Wood. 



Paper-pulp, souvenirs, boxes, book covers, and other small 

 articles, artificial limbs. 



Weight of Seasoned Wood in Pounds per Cubic Foot. 



2 3- 



Modulus of Elasticity. 



Modulus of Rupture. 



Remarks. 



Bark is unusual in the case of endogeneous trees. Arborescens 

 refers to fact that it is a tree. Artificial arms and legs are 

 made by bending veneers of yucca wood over moulds of the 

 stumps of amputated members. Shells are made up by the 

 aid of strong cements, and the "limbs" that result are 

 strong, tough, and very light. The processes are protected 

 by patents which include the methods by which the wood is 

 artificially toughened. f 



* See paragraph Bark, Endogenous Trees, page 189. 

 t Yucca Limb Co., Los Angeles, California. 



