STANDLEY TREES AND SHRUBS OF MEXICO. 91 



Panicles broad, not pendent. 



Leaves 15 to 23 cm. long 14. Y. valida. 



Leaves 30 to 60 cm. "long. 



Panicles glabrous or the pedicels puberulent. 



15. Y. decipiens. 



Panicles tomentose 16. Y. periculosa. 



Leaves 4 to 5 cm. wide, rough. 



Style elongate 17. Y. macrocarpa. 



Style very short 18. Y. mohavensis. 



1. Yucca elata Engelm. Bot. Gaz. 7: 17. 1882. 



Yucca angustifolia radiosa Engelm. in King, Geol. Expl. 40th Par. 5: 496. 1871. 



Yucca radiosa Trel. Rep, Mo. Bot. Gard. 3: 163. 1892. 



Dry plains, Chihuahua. Western Texas to Arizona. 



Trunk simple or branched, sometimes 7 meters high ;* leaves very numerous, 

 usually 3 to 10 mm. vi^ide, long and very slender, with white margins ; inflores- 

 cence glabrous; flowers white, campanulate. " Palmilla " (New Mexico). 



2. Yucca rigida (Engelm.) Trel. Rep. Mo. Bot. Gard. 13: 65. 1902. 

 Yucca rupicola rigida Engelm. Trans. Acad. St. Louis 3: 49. 1873. 

 Chihuahua, Durango, and Zacatecas; perhaps also in Coahuila ; type from 



between Mapimi and Guajuquilla. 



Trunk simple or branched, sometimes 5 meters high; leaves thin, flat, 

 glaucous, 30 to 60 cm. long, 2 to 8 cm. wide, rather stiff, sharp-pointed, with 

 yellow margins ; inflorescence glabrous ; capsule about 5 cm. long. " Palma 

 San Jos6 (Zacatecas) ; "palmita" (Durango) ; "palmilla." 



A form with smooth, entire-margined leaves is var. inermis Trel. (Rep. Mo. 

 Bot. Gard. 22: 102. 1911). 



3. Yucca rupicola Scheele, Linnaea 23: 143. 1850. 

 Western Texas and doubtless in adjacent Mexico. 



Plants acaulescent; leaves 30 to 50 cm. long, 2.5 to 3 cm. wide, glaucous, 

 with brown or yellowish margins ; inflorescence glabrous ; flowers white or 

 greenish. 



A form with smooth-edged leaves is var. edentata Trel. (Rep. Mo. Bot. Gard. 

 22: 102. 1911). 



4. Yucca rostrata Engelm. ; Trel. Rep. Mo. Bot. Gard. 13 : 68. 1902. 

 Chihuahua and Coahuila ; type from Monclova, Coahuila. 



Trunk simple or branched 3 meters high or less, 15 to 20 cm. in diameter, 

 the wood very soft and spongy ; leaves about 1 cm. wide, somewhat glaucous, 

 striate, rather stiff, very pungent, with yellow margins ; inflorescence glabrous, 

 0.5 to 1 meter long, the flowers large, pendent, white, rarely tinged with purple ; 

 capsule about 5 cm. long. " Soyate " (Coahuila) ; "palmita." 



5. Yucca thompsoniana Trel. Rep. Mo. Bot. Gard, 22: 101. pi. 10-'f-107. 1911. 

 Coahuila ; type from Bufatello. Western Texas. 



Flowering while stemless, bi:t in age with a trunk a meter high ; leaves 35 

 cm. long and 1 cm. wide or smaller, nearly flat, rigid, bluish or somewhat gla-u- 

 cous, pungent, usually I'oughened on the back ; flowers about 4 cm. long ; fruit 4 

 cm. long. 



6. Yucca aloifolia L. Sp. PI. 319. 1753. 



Yucca serrulata Haw. Suppl. PI. Succ. 32. 1819. 



Veracruz, Morelos, and Yucatan; sometimes cultivated for ornament. West 

 Indies ; Gulf coast of the United States. 

 1 26651—20 7 



