IMPORTANT WESTERN BROWSE PLANTS 77 
flora is typical of Jamaica and, according to some authorities, is 
really native to Mexico and South America, its range now extending 
almost around the world, owing to introduction. Its exact range in 
the southern or southeastern United States depends in part on one’s 
viewpoint respecting its relation to P. glandulosa and velutina. P. 
julifiora long ago became naturalized in the Philippines and Hawaii, 
and in the latter locality is said to have spread (73) rapidly and 
become one of the most useful tree species, under the name of alga- 
roba, misapplied to mesquite because of its superficial similarity 
to the Old World carob (Ceratonia siliqua). 
SCREWBEANS (STROMBOCARPA SPP.) 
Serewbean (Strombocarpa odorata, syns. Prosopis odorata, P. 
pubescens, Strombocarpa pubescens), or screwbean mesquite (731), 
frequently called by the Mexican name tornillo (fig. 19), is a shrub 
or small tree, occasionally 30 feet high and about a foot in diameter, 
with stout whitish stipular spines and flaky bark. The species 
ranges from western Texas to southern Nevada, northern Lower 
California, and Chihuahua. It is characteristic of canyons and 
river valleys, reaching its best development in low, rich, sandy, or 
gravelly bottom lands, but is also found as a bush in the foothills 
at higher elevations, up to at least 4,500 feet; frequent associates 
are mesquite and hackberry. The small, yellowish, fragrant flowers 
first appear in early spring, and often several successive crops of pods 
ripen during the summer months, dropping to the ground in fall. 
As in mesquite, the most valuable forage is the thick, sweet, pulpy, 
yellowish, spirally twisted pods of the screwbean, which are remark- 
ably high in sugars and proteins and are both an energizing and 
fattening feed. These beans are often produced in great abundance 
and all classes of livestock, as well as native herbivores, eat them. 
Indians and Mexicans frequently eat the pods raw and sometimes 
erind them into a sort of meal for baking, as they do the mesquite 
pods.. Screwbean “ greens out” in spring, and from about April to 
June the tender season’s twigs and the young leaves are relished 
by all classes of livestock that can reach them. The mature foliage 
is more apt to be taken in the fall. Screwbean has a tendency to 
grow in dense thickets, which frequently occupy large areas, and this 
habit militates against its full utilization. The very hard wood is 
used extensively for fuel and fence posts. 
Dwarf serewbean (S. cinerascens), sometimes called ballhead 
screwbean, from the headlike (capitate) inflorescence, occurs in 
southwestern Texas, ranging southward into Mexico. Its browse 
value is probably somewhat similar to that of S. odorata, but its 
very small size (mostly 6 to 12 inches high) and diminutive foliage 
(the leafiets only one-sixteenth to one-eighth of an inch long), while 
conducive to full utilization, would provide far less forage than does 
the common screwbean. 
MIMOSA (MIMOSA SPP.) 
Mimosa is a very large genus, consisting of at least 300 species, 
widely distributed in the sub-Tropics and Tropics; its members are 
shrubs, small trees, woody climbers, or rarely herbs. About 20 
