116 TREES OF NORTH AMERICA 



3-lobed ivory-white style forming a triangular stigmatic tube. Fruit oblong or oval, 

 more or less distinctly 6-angled, 6-celled, usually beaked at the apex, baccate and 

 indehiscent or capsular and 3-valved, the valves finally separating at the apex; peri- 

 carp of 2 coats, the outer at maturity thick, succulent and juicy, thin, dry and 

 leathery, or thin and woody. Seeds compressed, triangular, obovate or obliquely ovate 

 or orbicular, thick, with a narrow 2-edged rim, or thin, with a wide or narrow brittle 

 margin; seed-coat thin, black, slightly rugose or smooth; embryo in plain or rarely 

 ruminate hard farinaceous oily albumen; cotyledon much longer than the short 

 radicle turned toward the small oblong white hilum. 



Yucca is confined to the New World and is distributed from Bermuda and the 

 eastern Antilles, through the south Atlantic and Gulf states, and through New Mex- 

 ico and northward along the eastern base of the Rocky Mountains to South Dakota, 

 westward to middle California, and southward through Arizona, Mexico, and Lower 

 California to Central America. About thirty species with many varieties and probable 

 hybrids are recognized. Of the species which inhabit the territory of the United 

 States nine assume the habit and attain the size of small trees. The root-stalks of 

 Yucca are used as a substitute for soap, and ropes, baskets, and mats are made from 

 the tough fibres of the leaves. Many of the species are cultivated, especially in 

 countries of scanty rainfall, for their great clusters of beautiful flowers, or in hedges 

 to protect gardens from cattle. 



The generic name is from the Carib name of the root of the Cassava. 



CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES. 



Flower-clusters usually sessile, or short-stalked. 



Fruit pendulous, with thick succulent flesh ; seeds thick ; albumen ruminate. 

 Segments of the perianth slightly united at the base. 

 Panicle glabrous or puberulous. 

 Ovary stipitate. 



Leaves sharply toothed on their horny margins, smooth, dark green, slightly con- 

 cave. 1. Y, aloifolia (C). 

 Ovary sessile. 



Leaves concave, blue-green, rough on the lower siirfaee. 



2. Y. Treculeana (E). 

 Leaves concave above the middle, smooth, light yellow-green. 



Style elongated. 3. Y. macrocarpa (E, H). 



Style short. 4. Y. Mohavensis (G, H). 



Panicle coated with hoary tomentum. 



Leaves concave, smooth, light yellow.-green. 5. Y. Schottii (H). 



Segments of the perianth united below into a narrow tube. 



Leaves flat, smooth, dark green. 6. Y. Faxoniana (E). 



Fruit erect or spreading, the flesh becoming thin and dry at maturity ; seeds thin ; albu- 

 men entire. 



Leaves concave above the middle, blue-green, sharply serrate. 



7. Y. arborescens (F, G). 



Leaves thin, flat or concave toward the apex, rough on the lower surface, dull or 



glaucous green, more or less plicately folded. 8. Y. gloriosa (C). 



Flower-clusters long-stalked ; fruit capsular, erect, finally splitting between the carpels 



and through their backs at the apex ; seeds thin ; albumen entire. 



Leaves thin, flat, filamentose on the margins, smooth, pale yellow-green. 



9. Y. radiosa (E, H). 



