152 



The Yuccas 



Fruit dehiscent; southwestern tree. 

 Fruit indehiscent. 



Seeds thin, flat, narrowly margined; fruit soon becoming dry; south- 

 eastern tree. 

 Seeds thick or quite marginless; fruit drooping, fleshy, edible. 



Ovary stalked; fruit coreless, the pulp purple; leaf margin horny, 



sharply toothed; southeastern tree. 

 Ovary not stalked; core of fruit papery, the pulp greenish or yellowish 

 white; leaves concave, more or less filiferous. 

 Leaf margins slightly toothed; tree of Texas and Mexico. 

 Leaf margins not toothed. 



Leaf margin thin and flexible, the threads very firm; peduncle 



hairy. 

 Leaf margin thick and stiff, the threads coarse; peduncle not hairy. 

 Style elongated; Texas. 

 Style short; Arizona. 



1. Y. elala. 



2. y. gloriosa. 



3. Y. aloijoUa. 



4. Y. Treculeana. 



5. r. ScJwltii. 



6. Y. Torrcyi. 



7. Y. mohavensis. 



I. SOUTHERN YUCCA Yucca elata Engelmann 



Yucca radiosa (Engelmanii'l Trelease. Yucca augustijolia radiosa Engelmann 

 Yucca cflustricta Baker, also Sargent, not Buckley 



A simple or sparingly branched tree of the high, dry plains of southwestern 



Texas to southern Arizona and adja- 

 cent Mexico. Its maximum height 

 is 7 meters. It is also called Spanish 

 bayonet and Spanish dagger. 



The trunk is usually simple and 

 covered nearly to the ground by the 

 persistent dead leaves. The rind, 

 which is sometimes exposed at the 

 very base of the trunk, is about 6 

 mm. thick and broken into thin ir- 

 regular scales of a dark brown color. 

 The leaves are yellowish green, rather 

 stiff and diverging, linear, 5 to 7.5 

 dm. long; the clasping base is 3 to 6 

 cm. wide, thin, whitish, and is ab- 

 ru})tly narrowed to the gradually 

 tapering blade, which is about 7 mm. 

 broad at the middle, thin and flat 

 above, slightly rounded beneath, stiff, 

 brownish tipped, the margins entire, 

 thin, and white, splitting into very 

 The flowers, opening from May to July, are in branched 



Fig. 112. Southern Yucca 



long slender threads. 



panicles 1.2 to 1.8 meters long, the smooth stalks of which are about the same 



