175. YUCCA ARBORESCENS TREE YlTCCA, JOSHUA TREE. 57 



and indehiscent (excepting slightly when thoroughly dry), with dry spongy peri- 

 carp about i in. thick; seeds in. or less in diameter about -^ in. thick; albumen 

 entire. 

 The specific name, arborescens, is the Latin for becoming a tree. 



This very strange tree occasionally attains the height of 30 or 40 ft. 

 (10 m.), with a stout trunk 2 or 3 ft. (0.8 m.) in diameter, and, what 

 is contrary to expectation with an endogenous stem, covered with a, 

 thick gray bark furrowed longitudinally and checked into yielding, 

 corky plates and ridges. It forms a broad rounded or ovoid, quite 

 symmetrical head, with its thick contorted branches, only at the tips 

 of which are seen the tufts of growing leaves. Below these are the 

 conspicuous reflex withered leaves which long persist, until finally, 

 wasting away by the action of the elements, their shredded bases alone 

 remain, and they finally fall off in patches revealing its elm-like fis- 

 sured bark. 



HABITAT. The Mohave Desert, in southern California, where it 

 reaches its greatest development and forms open forests of considerable 

 extent, and thence northeastward through southern Nevada and north- 

 western Arizona to the Beaverdam Mountains in Utah, growing along 

 gravelly slopes at the bases of mountains and on mesas from 2,500 to 

 7,000 ft. elevation. 



PHYSICAL PROPERTIES. Wood light, soft, spongy, of a creamy- 

 white color, and, what again seems strange for an endogenous stem, its 

 fibrovascular bundles are arranged in a somewhat annular manner. 

 Specific Gravity, 0.3737; Percentage of Ash, 4.00; Relative 

 Approximate Fuel Value, 0.3588; Weight of a Cubic Foot in 

 Pounds, 23.29. 



USES. An attempt has been made to utilize this wood for paper 

 pulp, but the process of manufacture was found to be too expensive to 

 be practical. Cut into thin layers, the wood has been found to be 

 excellent to wrap about the stems of young fruit trees to protect them 

 against girdling by mice, etc. 



NOTE. The trunks of the Yucca are attacked by some borer which 

 excavates a devious tunnel about J in. in diameter, and the tissues of 

 the wood adjacent to it for about one-half inch or more in, become in- 

 filtrated with a substance which preserves it for a long time from decay 

 and renders it of such hardness as to turn the edge of the hardest 

 steel. These hardened portions of a reddish brown color may be 

 found as the only remnants of trunks otherwise quite completely de- 

 cayed, and are gathered by the country people as the choicest bits of 

 fuel obtainable. They speak of the material as " petrified wood," and 

 say that it burns with very little smoke and great heat. 



