76 MISC. PUBLICATION 101, U. S. DEPT. OF AGRICULTURE 
(126) intimates that it also occurs in Peru and Argentina. The 
shrub inhabits dry, sandy, or gravelly plains, canyons, and hillsides 
between about 2,500 and 5,000 feet, the tops of many low broad hills, © 
and larger areas of sand hills. The flowers appear from April to 
June and the pods reach maturity in September and October; not 
infrequently, however, flowers are again produced in early winter © 
resulting in an early (about July) crop of pods. 
The most valuable forage feature of this species is the pod or bean, — 
4 to 8 inches long when ripe, and sweet and pulpy within, very rich 
in protein (40, 141), and exceptionally palatable and nutritious. All — 
kinds of domestic livestock, horses, cattle, sheep, goats, and swine, — 
as well as numerous native mammals, seek these pods. They are 
also a staple food among many of the Indians and Mexicans. 
Honey mesquite “ greens out” in the spring before the leaves ap- 
pear, and these green twigs are readily grazed by livestock at that 
time. In drought years the mature twigs and leaves are taken 
fairly well by all classes of livestock before summer rains stimulate 
the growth of other forage; otherwise these parts are seldom taken 
by cattle unless the range as a whole is overgrazed or in fall and 
winter when there is marked scarcity of other feed. However, the © 
leaves fall early and hence are often not available for late summer — 
use. | 
It is all but impossible to kill honey mesquite and its close rela- | 
tive, Prosopis velutina, by overgrazing. ‘The fact that many of the © 
seeds pass out of the digestive tract undigested and viable accounts 
largely for the persistent spread of the plant. The plant is also | 
maintained in spite of overgrazing by reason of its phenomenal root — 
development, which perhaps exceeds that of any other observed plant 
species. The roots, in addition to a considerable lateral spread, have 
vertical ground penetration that in many instances reaches 30 feet, 
and has been reported to reach 60 feet below the surface. The fact — 
that the distribution of honey mesquite is spreading, owing to its 
natural aggressiveness and the fact that it resists prolonged range 
overgrazing at the expense of its competitors, have caused some 
writers to deprecate mesquite as forage. This is especially so on the 
eastern borders of the species’ range, where it is taking possession of © 
erasslands. 
Honey mesquite has a number of uses in addition to its forage 
value. The root. wood, being very hard and having little sapwood, 
makes first-class coals, and in many localities is excavated with great 
labor as the chief source of fuel. The aerial trunks of the tree are 
in great demand for fence posts. Also, a gum similar in properties 
and value to gum arabic is sometimes extracted in commercial 
quantities. 
The species is a famous honey plant, the nectar of the flowers 
making an exceptionally high-grade honey. A popular beverage, 
atole, is made from the cooked and strained beans (59). | 
Velvet mesquite (P. velutina) and common mesquite (P. juli- 
flora) are the only other species occurring in the United States, | 
both having forage value and properties very similar to those of 
P. glandulosa. P. velutina (pl. 5, B) occurs in Arizona, Sonora, 
and Lower California. It is regarded by many botanists as a 
variety of P. julifiora, being called P. juliflora velutina. P. juli- 
