SCIENTIFIC PAPERS. 
THE YUCCEAE.* 
BY WILLIAM TRELEASE. 
INTRODUCTION. 
The large family Liliaceae has been subjected to very 
different treatment by the writers who at various times 
have monographed it or attempted to indicate a natural 
sequence for its genera. The tribes Aloineae and Yuccoi- 
deae, respectively African and American, were treated to- 
gether by Mr. Baker ¢ with the implied recognition of 
close affinity, the principal synoptic differences between 
them consisting in the succulent leaves and gamophyllous 
perianth of the former, and the less succulent more fibrous 
leaves and distinct perianth segments of the latter, in 
which he includes Yucca, Hesperaloe, Herreria, Beau- 
carnea, and Dasylirion.t 
Bentham and Hooker § also place the aloids and yuccoids 
close together, characterizing the tribe Dracaeneae, in 
which the latter are included, by its mostly distinct perianth 
segments, and including in it Hesperocallis, Hesperaloe, 
Yucca, Nolina ( Beaucarnea), and Dasylirion, of the New 
* Presented in abstract, with lantern illustrations, before the Botan- 
ical Society of America, at its New York meeting, June 28, 1900, and 
before the Academy of Science of St. Louis, Feb. 3, 1902. 
+ Journ. Linn. Soc. Bot. 18: 148. (1881). 
+ 1. ot62. 
§ Genera Plantarum. 3: 750, 777. (1883). 
{ The generic descriptions show that the segments are connate into 
a tube in Hesperocallis, Dracaena, Cordyline, Milligania, and some lad 
of Astelia, and barely united at the base in Yucca. —1. c. 778. 
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