198 MISC. PUBLICATION 423, U. S. DEPT. OF AGRICULTURE 



4. Yucca elata Engelm., Bot, Gaz. 7: 17. 1882. 



Central and southern Arizona, 1,500 to 6,000 feet, grassland and 

 desert, May to July. Western Texas to southern Arizona and north- 

 ern Mexico. 



Soaptree yucca, palmilla, In Arizona, mature plants usually have 

 well-developed stems and often are very tall, but a stemless form 

 has been found at Camp Verde, Yavapai County {Peebles 14413). 



This species has proved useful as emergency ration for stock during 

 periods of drought. The chopped stems mixed with concentrated 

 food, such as cottonseed meal, are nourishing and palatable. Plants 

 sprout from the roots but cannot be cropped too often because of the 

 slow rate of growth. The roots, known as amole, are detergent and 

 have been used in the manufacture of shampoo soap. A substitute 

 for jute has been manufactured from the leaf fiber. Indians eat the 

 young flower stalks and lower portion of the stem. 



5. Yucca brevifolia Engelm. in S. Wats, in King, Geol. Expl. 40th Par. 



496. 1871. 



Clistoyucca arborescens (Torr.) Trelease, Mo. Bot. Gard. Ann. 

 Rpt. 13: 41. 1902. 



Western Mohave County, southwestern Yavapai County, and 

 northern Yuma County, up to about 3,500 feet, deserts, March to 

 May. Extreme southwestern Utah, southern Nevada, Arizona, and 

 southeastern California. 



Joshua-tree. Plant 5 to 12 m. high; leaves 15 to 37 cm. long, 8 to 

 15 mm. wide. In var. jaegeriana McKelvey {Y. brevifolia var. 

 woljei Jones), which has been found in extreme northwestern Mohave 

 County {Jones 5008, McKelvey 4160), the plant is 3 to 3.5 m. or rarely 

 6 m. high, branching near the ground, the branches short, rarely 

 spreading, the leaves 10 to 22 cm. long. 



6. Yucca schottii Engelm., Acad. Sci. St. Louis Trans. 3: 46. 1873. 

 Greenlee, Pinal, Cochise, Pima, and Santa Cruz Counties, 4,000 to 



6,000 feet, hillsides and canyons, April to August, type from moun- 

 tains west of the Santa Cruz River, probably in Santa Cruz County. 

 Extreme southwestern New Mexico, Arizona, and northern Mexico. 

 Hoary yucca. A large, handsome species, often cultivated. 



7. Yucca mohavensis Sarg., Gard. and Forest 9: 104. 1896. 

 Western Mohave County, up to 3,500 feet, deserts, March and 



April. Southern Nevada, Arizona, California, and Baja California. 



Mohave yucca. According to McKelvey's interpretation, the 

 valid name for this species is Yucca schidigera Roezl. 



8. Yucca baccata Torr., U. S. and Mex. Bound. Bot, 221. 1859. 

 Common and well distributed throughout the State, except in the 



lower desert regions, 3,000 to 8,000 feet, April to July. Southern 

 Colorado to Nevada, western Texas, Arizona, and southern Cali- 

 fornia. 



Blue yucca. Plant acaulescent, or with a few procumbent stems. 

 In var. vespertina McKelvey the plant is cespitose with many short, 

 procumbent to erect stems. The variety, which is common in north- 

 ern Mohave County, also has been collected in Yavapai, Graham, 

 and Apache Counties. 



Yucca confinis McKelvey is characterized by few or solitary stems, inflorescence 

 well exserted, peduncle 30 to 45 cm. long, often flexuous, leaves smooth to the 



