164 MISC. PUBLICATION 101, U. S. DEPT, OF AGRICULTURE 
Threadleaf snakeweed (G. mucrocephala, syn. G. filifolia) is a 
near shrub, woody only on the crown and very stem bases; it ranges 
from southern Idaho to western Texas and Arizona, occurring on 
dry plains and foothill and mountain slopes between about 3,500 
and 7,500 feet, mainly in bunched growth in the woodland type 
and on overgrazed grama range. It is unpalatable and seldom ob- 
served to be touched by livestock, its increasing abundance on a 
range being an almost infallible indication of overgrazing. It may 
possess active chemical properties and perhaps be deleterious; Mrs. 
Stevenson (7/29) states that the Zuni Indians steep the flower heads 
in boiling water and use the tea as a diuretic, sudorific, and tonic, 
and that their name for the plant, kiahapoko, refers to its being an 
indicator of the presence of water. 
Cudweed Tribe (Gnaphalieae) 
Arrowweed (Pluchea sericea, syns. Berthelotia sericea, P. borealis), 
also known by the vernacular names arrowbush, arrowwood, cacha- 
nilla, cachimilla, and osikakamuk, is probably the only western 
shrub of this group. Arrowweed, whose tall wandlike stems 
were prized by Indians for making arrows, occurs along streams, in 
river bottoms and valley lands, largely in brush-annual types from 
sea level up to 2,500 feet or so, from Lower California to scuthern 
Utah and Colorado and western Texas and south into Mexico. It is 
perhaps the most abundant plant along the lower stretches of the 
Colorado River. The silvery-hairy herbage is nipped to some extent 
by cattle and horses. 
Sunflower Tribe (Heliantheae) 
ENCELIA SPP. 
Excluding the herbaceous genera Enceliopsis, Geraea, and Simsia, 
which some (especially of the older botanists) include in Encelia, 
there are about six valid species and three subspecies, or varieties, of 
Encelia occurring in the western United States, all shrubs, and 
often known locally as desert sunflower. The browse value is rather 
low except that cattle and sheep pick off the sunflowerlike flower 
heads, but animals of any description will very seldom nibble the 
leaves. 
White brittlebush (2. farinosa), a name suggested by Hornaday 
(64) because of the whitish stems and leaves and because the elon- 
gated, naked flowering stems become dry and brittle after the seeds 
mature, is probably the commonest and most familiar species. Other 
vernacular names include brittlebrush, golden hills, incienso, starchy 
encelia, tohafs (Pima), and whitebush. Palmer (139) states that 
Mexicans call it incienso because of the amber-colored, fragrant gum 
exuded by the plant. In appearance it is a bush 1 to 5 feet high, 
usually with a short trunk and a broad crown.*? It ranges from 
Lower California to southern Utah and northern Sonora and is a 
typical desert plant of the plains and lower foothills, very common 
2 Coville (26) has called attention to the fact that annual rings are indistinguishable 
in the moderately hard wood of the old stems of this species, that the bark is extraordi- 
narily close and compact, and that the leaf hairs are simple and unicellular, whereas 
those of the related #. frutescens (of about the same range) are 3 to 5 celled. Mrs. 
Shreve has shown (122) that this shrub bears two distinct types of leaves—a mesophytic 
type in cool months and a xerophytic, matted-hairy type in arid Seasons; also (123) that 
the species has about one-fifth of the transpiration in June that it has in January. 
