PARTIAL THERMOSTASY OF THE GROWTH CENTER OF 
THE DATE PALM 1 
By Silas C. Mason 
Horticulturist , Office of Crop Physiology and Breeding Investigations , Bureau of 
Plant Industry, United States Department of Agriculture 
INTRODUCTION 
The date palm {Phoenix dactylifera ) is the most important member 
of the great palm family, excelling even the coconut palm in its 
economic value to the human race. Its culture is one of the most 
ancient of which we have records, being recognized in Assyrian 
tablets of very ancient date, and possibly even earlier in architec¬ 
tural decorations in Egypt. Soon after the children of Israel had 
escaped from Pharaoh across the Red Sea we are told in Sacred 
Writ 2 that “they came to Elim, where were twelve springs of water 
and threescore and ten palm trees: and they encamped there by the 
waters.” The springs are there to this day, and some palms. The 
place is called in the Arab tongue “Ain Musa”—“The Springs of 
Moses.” 
In its climatic requirements the date palm is in strong contrast 
to the coconut palm, which finds favorable environment along 
tropical reefs and shore lines having abundant rains and an almost 
saturated atmosphere, yet without excessive temperatures, and 
which is tolerant of only the very lightest frosts. The date palm, 
though fruiting in some coastal regions like northern Egypt, requires 
a practically rainless season for the perfect development of its fruit, 
and is at its best in hot interior regions having very nigh temperatures 
and low humidity. The practical culture of this palm in the northern 
hemisphere extends southward to about 15° latitude, but ceases 
where the region of tropical rains begins. In west Africa the com¬ 
mercial production 6f dates is confined to the region on the south 
side of the great Atlas range, although beautiful specimens of non¬ 
productive trees may be seen at Algiers and other Mediterranean 
cities. A small but very significant commercial culture of the 
date palm is maintained at Elche, in the southeastern part of the 
Spanish Peninsula, at a latitude just above 38°, the most northerly 
point of commercial date culture in the world. Nonfruiting trees, 
may be seen at most points along the northern Mediterranean coast, 
even extending to Venice at 45° on the Adriatic, but fruit production 
reaches only a latitude of 35° in Mesopotamia, 34° in Persia, and 
about 30° to 33° in the Punjab in India. 
In the United States, to which the cultivated varieties of dates 
of Africa and Mesopotamia have been transplanted, fruit has been 
successfully matured only as far north as 30° to 33° in Arizona and 
about 34° in California, with possibilities of commercial develop¬ 
ment as far north as 36° or even 38° in the interior valleys. These 
data show the approximate range of date culture in the northern 
1 Received for publication September 29,1924; issued October, 1925. 
a Exodus xv, 27 
Journal of Agricultural Research, 
Washington, D. C 
(415) 
Vol. XXXI, No. 6 
Sept. 1, 1925 
Key No. G-477 
