May, 1893.] YUCCAS OF THE DEATH VALLEY EXPEDITION. 3o7 



Pahranagat Mountains. — Common on the Pahranagat Mountains from 

 the summit of the pass between Pahranagat and Timpahute valleys 

 (altitude 1,830 meters or 6,000 feet) down on the west side to the edge 

 of Timpahute Desert at an altitude of 1,525 meters (5,000 feet), and 

 down on tbe east side sparingly to within a mile of the bottom of 

 Pahranagat Valley at an altitude of 1,280 meters (4,200 feet), and 

 forming a fair forest above 1,400 meters (4,000 feet). Stunted and 

 scattered trees stretch thence southerly all along the gravel slope on 

 the west side of Pahranagat Valley at the foot of the Pahranagat 

 Range. On the west slope of the Pahranagat Range (on the east side 

 of Timpahute Valley) the trees are sufficiently near together to form a 

 fair yucca forest between an altitude of 1,390 meters (4,600 feet) and 

 the summit of the divide. 



Highland Range. — The most northerly forest of tree yuccas found 

 in eastern Nevada is on the west slope of the Highland Range south 

 of the dry lake in Desert Valley, and southeast of Pahroc Spring. 

 This forest is at least 5 miles wide and 10 miles long, and may stretch 

 away much further to the south. Apparently it begins at an altitude 

 of about 1,670 meters (5,500 feet) on the desert side, and ranges up to 

 2,000 meters or higher (probably to 6,500 or 7,000 feet) on the west 

 slope of the mountains. 



Pahroc Range. — A few scattering and stunted tree yuccas grow at 

 Point of Rocks, the southernmost spur of the Pahroc Range near 

 Pahroc Spring. These are the northernmost trees of which we have any 

 knowledge. The high base level of Pahroc Plain explains the un- 

 usually high altitude at which they grow. 



Charleston Mountains. — On the west slope of the Charleston Mountains 

 (Pahrump Valley side), below Mountain Spring, tree yuccas begin at 

 an altitude of about 1,060 meters (3,500 feet), and become more and 

 more abundant until they form an open forest in the upper Larrea, and 

 Goleogyne belt, mixing with the junipers at 1,525 meters (5,000 feet), 

 and pushing 60 to 90 meters (200 or 300 feet) higher. on favorable slopes, 

 finally stopping at an altitude of about 1,600 meters (5,300 feet). The 

 individual trees are smaller than those of the Mohave Desert, rarely 

 exceeding 4£ meters (15 feet) in height. In the lower part of this belt 

 Yucca arborescens is mixed with unusually large examples of Yucca 

 macrocarpa, and in the upper part with the elegant Yucca baccata. 



ARIZONA. 



Northicestern comer. — On the mesa west of the Virgin River and about 

 8 miles south of the mouth of Beaverdam Creek, near the boundary be- 

 tween Arizona and Nevada, is a scattering belt of tree yuccas a mile 

 or a mile and a half in breadth, ranging from an altitude of about 670 

 meters (2,250 feet) on the Virgin Valley slope to the top of the mesa at 

 740 meters (2,450 feet). 



R/etrital Valley. — Mr. Vernon Bailey informs me that Yucca arbor- 

 escens forms an extensive forest on the low divide between Detritalund 



