116 MISC. PUBLICATION 101, U. S. DEPT. OF AGRICULTURE 
Canotia (Canotia holacantha), also called crucifixion thorn, 
Mohave-thorn, paloverde, and tree of Christ, is placed by some 
botanists in the Celastraceae. It is a shrub or small tree, 5 to 30 feet 
high, with ephedralike branches, occurring in Arizona and southern 
California on hot desert lands at 2,000 to 40 00 feet. Although worth- 
less as browse, the wood is hard and makes good fuel. In parts of 
Arizona it often grows in pure stands each several acres in extent, 
and assists in erosion control in sandy soils and dry washes. 
All-thern (Aoeberlinia spinosa), known aiso as abrojo, corona de 
Cristo, crown-of-thorns, and junco, occurs from western Texas to 
southern Arizona and southward into Mexico, growing on dry grav- 
elly mesas and the like. Occasionally it has a trunk and is a small 
tree, but usually is a low sprawling intricately branched bush, seem- 
ingly entirely composed of thorns, “and f forming @ veritable chevaux- 
de-frise over considerable areas, making it a oreat pest to the stock- 
man and traveler. The hard, resinous wood makes a hot fire but 
the odor is unpleasant. Its growth habit is reminiscent of that of 
Holacantha emoryt, a very thorny, practically leafless shrub or small 
tree of the Simaroubaceae, or Quassia family, found in deserts of 
southern California, scuthern Arizona, and northern Sonora, and 
also locally called crucifixion thorn and corona de Cristo. 
CACTUS FAMILY (CACTACEAE) 
This huge natural family of North America and South America 
is of western range forage significance primarily because of the use 
of certain Opuntia species as emergency feed. However, there are 
in the faraily numerous representatives of economic and other 
interest. 
PRICKLYPEARS AND CHOLLAS (OPUNTIA SPP.) 
Opuntia isa very large genus, best represented in the United States 
in the strip of southern border States from Florida to California, 
more especially from Texas westward. The cylindrical-stemmed 
species are known as chollas, cane-cacti, tasajillas, etc. (fig. 33, A, B), 
while the flat-jointed species are familiarly known as pricklypears. 
(Fig. 33, C, D, and pl. 8, B.) There is, however, a wealth of Mexi- 
can and aboriginal names for various groups and certain individual 
and well-marked species. 
Obviously the so-called “spineless” or smooth varieties of 
Opuntia are superior to the spiny forms as range livestock feed, but 
no species of the genus Is wholly free from either spines or prickles, 
and the term “spineless” must be interpreted as a relative one. Un- 
fortunately the spineless species (such as, for example, O. dillee, O. 
sphaerocarpa, and O. treleasev) are apt to be rare and local on the 
range and not so aggressive under range conditions as are the spiny 
species. However, spineless varieties, both native and introduced, are 
cultivated (especially in Texas) as forage plants. In practical 
range usage, however, there is a more eeneral tendency to utilize 
the more common, hardy, and available spiny species by first singe- 
ing off the spines with a gasoline torch. When the spines are re- 
moved there is no question about the palatability of these plants to 
livestock and they are a valuable source of water in arid regions. 
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