150 
Journal of Agricultural Research 
Vol. I, No. a 
is nowhere subject to the severe cold endured by the Nevada “wild 
almond” in its most northern habitat. It usually grows in gravelly 
formations or along washes or sandy slopes where deep root penetration 
is possible. 
This “ desert almond” is remote geographically from the two species of 
the group to which it is most nearly allied, the Texas wild almond, Prunus 
minuliflora, and its Mexican cousin, Prunus microphylla, which may 
consistently be called the “Mexican wild almond.” 
The Texas species has a range not yet well worked out, but it is appar¬ 
ently confined to the Cretaceous limestone region of the southwestern 
portion of the State, extending across the Rio Grande into the State of 
Chihuahua, Mexico, and probably occurring in Coahuila. Its known 
localities are entirely in the upper portion of the Tower Sonoran zone. 
(Fig. 2.) It is found over an area ranging in altitude from 750 feet near 
San Antonio to 3,000 feet near the mouth of the Pecos River, with an 
average rainfall of about 20 inches, but subject to periods of prolonged 
drought. There is an absolute temperature range for the years recorded 
of from zero to no° F., with the liability to sudden drops from winter 
northers, peculiar to this region. 
Of the conditions under which the Mexican species grows we have but 
indefinite knowledge, but it occurs at high altitudes—6,000 to 8,000 feet, 
the Upper Sonoran zone of this southern latitude, probably a mild tem¬ 
perate climate with light winter rains and heavy summer showers. In 
common with the other species it grows in a region where the setting of 
the fruit is frequently prevented by late spring frosts. 
The little-known Havard’s wild almond, Prunus havardii , apparently 
a near relative of these two species last mentioned, has been found so far 
only in western Texas. 
The Texas “wild peach,” Prunus texana , occurs in scattered localities 
over a region of eastern Texas from near sea level to nearly 2,000 feet in 
elevation, lying wholly in the Lower Sonoran or Lower Austral zones. 
This includes a portion of the western extremities of the com and cotton 
belts, where an apparently sufficient annual rainfall is so unevenly dis¬ 
tributed that long periods of drought make agriculture somewhat pre¬ 
carious and render irrigation a needful adjunct. It is adjacent to the 
area of Prunus minutiflora, but the division with its sharp demarcation 
is not one of climate, but of soils. Prunus minutiflora follows the Cre¬ 
taceous limestone of the plateau region, while Prunus texana occurs on 
the mellow granitic sandy soil of the “Burnet Country” or the sandy 
loam of the Coastal Plain and is wholly wanting on limestone soils. 
(See map, fig. 2.) 
