CERTAIN DESERT PLANTS AS EMERGENCY STOCK PEED. 7 



are used for this purpose. This confusion of usage explains how two 

 people may disagree about certain peculiarities of soap weed; they 

 • are probably thinking and talking of two different plants. 



OTHER THICK-LEAVED PLANTS. 



The yuccas may be recognized when not in flower by characters 

 which apply to all the species of the region except three. The leaves 

 of all species are each tipped with a sharp spine, and the margin of 

 the leaf bears one or more threadlike fibers which frequently strip 

 back and form a loose mat of threads among the bases of the leaves. 

 The margins of the leaves never bear any hooklike spines. In one 

 group of three species that grow in the region of Del Rio, Sanderson, 

 and northward in Texas the leaf margins do not have a threadlike 

 appendage, but are thickened and horny, with very fine teeth, 

 scarcely large enough to be seen by the naked eye, but sharp enough 

 and hard enough to cut the hands badly. 



Of the other thick-leaved plants of the region the century plants 

 (Agave) all have sharp spines on the ends of the leaves, but the 

 margins bear large recurved spines. Sotol (Dasylirion) has flat, 

 strap-shaped leaves with curved, yellow, horny spines on the margin, 

 but they are frayed at the tips. (PL V, fig. 2.) There are two or 

 three species of Nolina in the region that have long, slim, nearly 

 smooth, but tough leaves, frayed at the tips, without threads or 

 spines, though sometimes a few very small teeth are scattered along 

 the margin. The leaves of these plants are often as thick as they are 

 wide, which is usually not much over one-fourth of an inch, being 

 nearly always triangular, but sometimes nearly circular in cross sec- 

 tion. In the region about Marathon and Sanderson, Tex., where one 

 species {Nolina erumyens) 1 is tolerably abundant, the common 

 name in use is sacahuista. 2 (PI. VIII, fig. 1.) 



BEAR-GRASS. 



Bear-grass is a name that is used for two very different plants in 

 different localities. On the Plains of eastern New Mexico and western 

 Texas from Carlsbad northward to western Kansas and eastern Colo- 

 rado, found practically always on the sandy land, the plant called 

 bear-grass is a species of Yucca (Y. glauca; PL IV, fig. 2) that has 

 many narrow, thin, thread-bearing leaves that are borne on a very 

 short stem growing from a rather large root from which new heads of 

 leaves arise whenever the old ones are cut off. The leaves are three- 

 eighths of an inch wide or less, hardly more than one-sixteenth of an 

 inch thick, and 18 to 30 inches long. The stem is usually not over 6 

 or 8 inches high. By using the same name for the two plants and 

 failing to recognize their differences (which are not marked in plants 



1 The variety called comvacta by Dr. Trelease is associated with the species throughout this region. 



2 This name is also applied to a species of Spartina, a coarse grass, in the coastal-plains region of Texas. 



