500 



SCIENCE. 



[N. S. Vol. XVII. No. 430. 



species bearing evergreen, erect, sharp-pointed 

 leaves. On the Great Plains a common species 

 is known as the ' Dagger-vceed.' In the south- 

 west some of the species attain to the dimen- 

 sions of trees, as Yucca australis and Y. 

 valida, and are known as ' bear-grass,' ' palma 

 loca,' ' izote,' etc. Botanically they are closely 

 related to the lilies, and in fact are classed as 

 members of the Lily family, of the tribe 

 Dracwnoidew, and subtribe Yuccew. All are 

 natives of North America (including Mexico) 

 and Central America. 



In this paper the author describes thirty- 

 four species and forty-five varieties and 

 ' forms.' These are distributed quite un- 

 equally among five genera, as follows: Hes- 

 peraloe, two species, and one variety; Hes- 

 peroyucca, one species; Glistoyucca, one 

 species; Yucca, twenty-eight species, and 

 forty-five varieties and 'forms'; Samuela, two 

 species. The species of Hesperaloe occur in 

 Texas and Mexico, and have narrowed flowers, 

 in contrast with the remaining genera, in 

 which the flowers are broad. The single spe- 

 cies of Resperoyucca occurs in California, 

 and may be recognized by its filiform style. 

 In Glistoyucca, in which the style is wanting, 

 we find a single branching arborescent species, 

 which attains a height of twenty to twenty- 

 five feet or more, and a stem diameter of 

 nearly two feet. It occurs in the Mohave 

 Desert of California, northwestern Arizona 

 and southwestern Utah, where it is known as 

 the ' Joshua tree.' The numerous species, 

 varieties and ' forms ' of Yucca are widely 

 distributed, extending from South Dakota 

 southward to central Mexico, and from the 

 Atlantic Ocean to the Pacific. Species occur 

 also in Central America, the Bermuda Islands 

 and the eastern Antilles. The genus is dis- 

 tinguished by the polyphyllous flowers and 

 short style. The plants range from acaules- 

 cent, as in Yucca filamentosa and Y. flaccida, 

 to arborescent, as in Y. australis and Y. valida, 

 which may attain a height of twenty-five to 

 thirty feet. Samuela is a new genus erected 

 by the author to include the species with 

 tubular, gamophyllous flowers. Its two ar- 

 borescent species are natives of Texas and 

 northern Mexico. 



One outcome of the studies on which this 

 monograph is based is the conclusion that 

 most of the Spanish bayonets grown in gar- 

 dens under the old name of Yucca filamentosa 

 are not of that species, but are varieties of 

 the allied species. Yucca flaccida. The two 

 species may be distinguished by the more 

 rigid leaves, which bear coarse, curly threads 

 in Y. filamentosa, and the more flexible leaves, 

 bearing finer, straighter threads, in Y. flaccida. 



The yuccas are of some value economically. 

 All possess very fibrous leaves, and it is said 

 that ' local use is made of the fiber almost 

 everywhere that the plants grow.' The trunks 

 of the larger species are locally used in the 

 building of houses, palisades, etc., and the 

 leaves are used for thatching. On account of 

 their saponifying properties the stems and 

 rootstocks of some species are used as a sub- 

 stitute for soap, and the species so used bear 

 the local names ' amole,' ' soapweed,' ' soap 

 plant,' etc. Apparently some use is made of 

 this saponifying constituent in the manufac- 

 ture of certain proprietary soaps and deter- 

 gent compounds. The fiowers and young 

 leaves of many species are greedily eaten by 

 cattle. In the Nebraska sandhills the present 

 writer has seen many examples of plants which 

 had been broken down and their young leaves 

 eaten by the hungry cattle, and in these re- 

 gions it is very difiicult to find complete 

 flower panicles, on account of the gTeediness 

 of the cattle in eating the succulent flowers. 

 In Mexico the flower clusters of Samuela car- 

 nerosana are gathered for feeding to sheep 

 and other domestic animals, and it is the 

 practice of the inhabitants to split open the 

 thick trunks of this species in order that the 

 succulent interior portions may be eaten by 

 stock. The fruits of the baccate species are 

 eaten by the natives, as are the young flower 

 buds of some species when roasted or boiled. 

 The seeds are ground and used as meal or 

 boiled into a mush for human food, in some 

 localities. Lastly, attention may be called to 

 the ornamental value of many species, and for 

 this purpose they are largely employed, espe- 

 cially in gardens and parks of considerable 

 extent. They are not adapted to small 



