IMPORTANT WESTERN BROWSE PLANTS 165 
and abundant in dry, warm, rocky situations from sea level to 4,000 
feet, and often occurring in almost pure stands or associated with 
jojoba and F’ranseria deltoidea. The showy flower heads are some- 
times taken fairly readily by livestock. 
OTHER GENERA 
Tar-bush (Plourensia cernua), frequently called blackbrush, is a 
resinous, thick-leaved shrub, 3 to 6 feet high, ranging from western 
Texas to southern Arizona and Mexico. It is common and abundant 
on dry sandy, or adobe plains, mesas, and low foothills, frequently 
in association with creosote bush, mesquite, burrograss, and tobosa- 
erass, often occupying large areas and forming a rather distinctive 
vegetative type. Unfortunately the herbage has a peppery quality 
and, unless forced to do so, livestock will not touch it. 
Plains blackfoot (2/elampodium leucanthum), known also as 
plains melampodium and Easter daisy, which occurs from Kansas to 
Texas and Arizona and south into Mexico, growing on dry plains and 
slopes at 2,500 to 7,000 feet, in soils varying from pure sand to rocky 
or clayey loams, is doubtless the most familiar species of the genus 
blackfoot. This genus is represented in the Western States by about 
four indigenous species and about two others naturalized, from 
Mexico; they are herbaceous or somewhat woody perennials. Plains 
blackfoot is low and about half shrubby; its root and older stem 
growth are thickened and woody, but the season’s stems are slender 
and herbaceous. The showy flower heads are cropped to some extent 
by cattle, sheep, and goats, but otherwise the palatability is worth- 
less or low. 
Mariola (Partheniuwm incanum), known. also as horsebrush, mati- 
ola, New Mexican rubberbush, and sage, is a shrubby plant, growing 
scatteringly but commonly, mostly in the mesquite-covillea type, 
from extreme western Texas to southern Arizona and south into 
Mexico. Despite its peculiar taste and its rubber content the tender 
new shoots and the flower heads are sometimes nibbled by goats, 
cattle, and sheep. Wooton and Standley (147) indicate that it has 
been used, but without much practical success, for the production of 
rubber. Its congener, guayule, or Mexican rubberbush (P. argen- 
tatum), occurs indigenously as far north as western Texas and pro- 
duces rubber in commercial quantities; there are cultivated planta- 
tions of it in southern Arizona. 3 
Some of the woody species of Viguiera (syn. Gymnolomia) of the 
Southwest, such as V. helianthoides, V. parishit, V. stenoloba, V. 
tenuifolia, and V. texana, have limited browse utility, especially in 
southern Arizona and New Mexico. Livestock will frequently pick 
off the flowering and fruiting heads or, after frost, nibble the leaves. 
None of these plants seems to have a well-established, distinctive 
_ common name; they are usually known locally under the comprehen- 
sive term sunflowers. 
DOGWEEDS (DYSODIA® SPP., SYNS. ACIPHYLLAEA, BOEBERA, HYMENATHERUM, 
AND, IN PART, THYMOPHYLLA) 
Dogweeds, often called fetid-marigolds, comprise a group of 
about 20 species occurring in the West, mostly in the Southwest; a 
83Some authors have lately taken up the original spelling, Dyssodia. The writer 
strongly feels that Asa Gray was fully justified in changing the spelling to Dysodia (30). 
