90 CONTRIBUTIOlSrS FROM THE NATIOITAL. HERBARIUM. 



toilet soap. An extract of the roots has been employed to produce foam in 

 beverages. 



The plants are of some importance as forage, chiefly in times of severe 

 drought, when cattle often eat the stiff leaves. The flower panicles are much 

 eaten by cattle. The flowers, either in bud or just after they have opened, have 

 long been an article of human food in Mexico and they are frequently found in 

 the markets at the present time. They are eaten raw as a salad, or are cooked 

 in various ways, and are sometimes made into a conserve. They are slightly 

 bitter and are reputed to have tonic properties. 



The fruits of those species with baccate fruit, usually known as " datiles," 

 are eaten by birds and mammals and by man. They contain much sugar but are 

 more or less bitter. They are eaten either raw or cooked, and some of the 

 Indians, of the United States at least, dried them for use in winter. The fruits 

 are also fermented and sometimes distilled to produce an alcoholic beverage. 



Various statements are made concerning the seeds. Palmer reports that the 

 Indians used them for food. Others state that they are purgative, while Cer- 

 vantes says that they are useful for the treatment of dysentery. 



Many of the species of Ytccca are used as ornamental plants, especially in 

 arid regions. They are admirably suited for this purpose because of their 

 showy flowers and striking palmlike appearance. 

 Fruit dehiscent, erect. 



Leaves filiferous along the white margins. Plants with a tall trunk, 



1. Y. elata. 

 Leaves minutely denticulate on the margins, not filiferous. 

 Capsule beaked, the valves rounded on the back. 



Leaves about 60 cm. long; trunk about 3 meters tall 4, Y, rostrata. 



Leaves 20 to rarely 35 cm. long; trunk 1 meter high or less. 



5. Y. thompsoniana. 

 Capsule mucronate, the valves flat on the back. 



Plants with a tall trunk 2. Y. rigida. 



Plants acaulesceut i 3. Y. rupicola. 



Fruit indehiscent, baccate, pendent. 



Fruit without a core, the pulp piirple ; ovary stalked. Leaves sharply den- 

 ticulate but not filiferous 6, Y, aloifolia. 



Fruit with a papery core, the pulp greenish or whitish ; ovary sessile. 



Leaves not filiferous 7. Y. elephantipes. 



Leaves filiferous. 



Margins of the leaves denticulate at first. Leaves thick and firm, often 



rough 8, Y. treculeana. 



Margins of the leaves not denticulate. 



Leaves thin, flexible, smooth, the filaments slender. 



Leaves 2 to 4 cm. wide; trunk nearly simple 9. Y, schottii. 



Leaves 7.5 cm. wide; trunk much branched 10. Y, jaliscensis. 



Leaves thick, rigid, the filaments usually coarse. 



Leaves usually less than 2.5 cm, wide, smooth ; trunk usually less 



than 2 meters high 11, Y, treleasei. 



Leaves 2.5 cm. wide or wider, often rough ; trunk usually more than 

 2 meters high. 

 Leaves usually 2 to 4 cm. wide, smooth. 



Plants acaulescent 12. Y. endlichiana. 



Plants with an elongate trunk. 

 Panicles narrow, pendent 13, Y, australis. 



