Sept. 1, 1925 
Thermostasy of Growth of the Date Palm 
421 
with thousands of leaves and buds, and a paper-like shell, a veritable 
cast of the complete tree would have been thrust between last year’s 
bark and wood. Thus the twig growth, in length, was nearly all 
made in a single month; the addition of the woody shell continued 
for possibly four months. 
DATE PALM STRUCTURE 
In contrast with this typical exogenous tree, where the function of 
cell multiplication and growth is distributed through the cambium 
zone with its thousands of terminal buds, that of the date palm trunk 
is concentrated in the single giant terminal bud, or phyllophore, 4 
which at the same time is pushing up six or eight great leaves by 
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Fig. 3— Total twig growth for the season on selected trees of a New Hampshire apple orchard; 
below—mean air and soil temperatures for the corresponding period. The twig growth declines 
from the maximum to zero while the temperature advances 
intercalary growth at their bases, laying down flower spathes in their 
axils for next year’s crop, elongating the trunk from 12 to 18 inches a 
year, and bringing the trunk diameter in the tapering “cone of 
growth” up to the pattern set by the shaft below. Except at the 
growing tips of the multitude of ropelike roots, each pushed inde¬ 
pendently from the sperical base of the trunk, the growth area of 
this palm is close to the base of the crown of giant pinnate leaves, 
where the work of photosynthesis is performed and where, under the 
intense light and dry air of desert conditions, the large volume of 
« “ Phyl'lophor, Phyl'lophore, Phylloph'orum, (®opku >, I carry), the budding summit of astern on which 
leaves are developing, especially applied to palms.” Jackson, B. D. a glossary of botanic terms. 
Ed. 3, rev. and enl., 427 p. London. 1916. 
Apparently this term was first used by Mirbel (18) in a communication to the French Academy, Comp- 
tes Rendus, 12 Juin, 1843, p. 1216, from which is quoted the following: “ Quand on a terming ce travail, la 
structure de stipe devient aussi claire que d’abord elle paraissait obscure. En voici la raison: le bourgeon 
ne peut se developper qu’autant que de nouveaux filets penetrent dans le phylophore et se dirigent vers les 
jeunes feuilles.” 
Martius (15, p. LXXIV), who was contemporary with Mirbel and familiar with his work, notices the 
use of this term as follows: “Ilium locum, quern Germani botanici vocarunt gemmae nucleum ‘Knospen- 
kern. ’ novo nomine insignivit Mirbelius ‘Phyllophorum’.” 
