IMPORTANT WESTERN BROWSE PLANTS 89 
crevices of cliffs, and in New Mexico is scattered in the lower wood- 
land type between about 4,500 and 6,500 feet. It often occurs in 
places practically inaccessible to livestock, which seems to be 
fortunate. 
Chesnut (1/7) and the Bureau of Animal Industry report that 
mescalbean is generally regarded as poisonous to animals. The 
attractive-looking seeds, formed in the pods in late summer and fall, 
are virulently poisonous and contain the bitter alkaloid sophorin, 
which some chemists regard as identical with cytisin. Children have 
been known to die as a result of eating the seeds, one of which is said 
to be sufficient to kill an adult human being (59). Indians occasion- 
ally use a small quantity of the triturated beans to produce a form 
of intoxication and delirium from which a coma of two or three 
days’ duration ensues (95, 126, 116). 
Gorse (Ulex europaeus) is a multibranched bush (pl. 6), 2 to 6 
feet high and spreading out to a diameter sometimes of 10 feet or so, 
the branches very (mostly prickly) leafy, the twigs green and ending 
in spiny tips. Gorse, known also as furze, Scotch thistle (mis- 
nomer), thorn broom, ulim, and whin, is a native of Europe and is 
fugitive in the United States from Nantucket and eastern Massa- 
chusetts to eastern Virginfa, along or near the Atlantic coast, and 
along the Pacific from Vancouver Island to Oregon. Evidently its 
North American range is slowly spreading. It occurs in waste 
places, being especially characteristic of dunes and beaches near the 
ocean, though it adapts itself to xerophytic conditions inland. 
So far gorse seems to have been a negligible factor in the western 
forage crop; the spiny twigs and leaves are uninviting to range 
livestock, and on some ranges, pastures, and farms the species has 
become a pest. In the Old World, however, gorse is sometimes used 
as a winter fodder plant, the season’s growth only being employed. 
The species may have future possibilities in this country for silage 
or other economic purposes, or, contrariwise, as a pest. Gorse is a 
good sand binder and has been limitedly planted for this purpose; 
the lower branches stool out from the base, it survives burial in the 
sands, and is a copious seeder. 
CALTROP FAMILY (ZYGOPHYLLACEAE) 
Creosote bush (Covillea tridentata) (fig. 23), an evergreen, heavy- 
scented, resinous, diffusely branched shrub, 3 to 11 feet high, rang- 
ing from western Texas to southern Colorado, Nevada, Lower Cali- 
fornia, and Chihuahua, deserves notice here primarily because of its 
great abundance. It is known variously as gobernadora, grease- 
wood, hediondilla, and by numerous local (largely Indian or Mexi- 
can) names. The synonymy of this species is involved and hardly 
any two manuals agree as to the nomenclature. Larrea is an older 
generic name than Covillea but is a homonym and hence untenable. 
The proper specific name for creosote bush depends on the concept of 
the individual author, but C. glutinosa and C. mexicana appear to 
be synonyms of (. tridentata, while C. divaricata (the oldest name 
of all), typical of Chile, is probably a different species. 
Creosote bush is a very interesting plant to the ecologist, being 
perhaps the chief indicator of the Lower Sonoran Zone in the South- 
west, and occupies an enormous acreage of desert lands. It is al- 
