Feb., 1923] 
SEIFRIZ — CAUSES OF GREGARIOUS FLOWERING 
IOI 
inches of rain as compared with a normal average of 21.95 inches for this 
period. Especially trying must this drought have been on plant growth in 
view of the fact that the precipitation in April, which usually ends the 
normal dry season, was less than half the average, while in May there fell 
but 0.75 inch of rain as compared with a normal precipitation for this 
month of nearly five inches (4.90). In 1911 the talipot palms were but 
seven years younger than in 1918, i.e., they were thirty years old, not too 
young to respond sexually to an external stimulus of some force. 
Through all these droughts the six talipots, with others in the Peradeniya 
Gardens and hundreds throughout Ceylon, the twenty clumps of bamboo, 
and the liane Bauhinia, grew on without flowering. It is therefore hardly 
likely that the relatively mild drought of 1918 had any influence on the 
flowering of these plants. 
The second objection to be raised against the conclusion that drought 
caused the flowering of the plants in the Peradeniya Gardens is that nine 
out of the sixteen talipot palms did not flower, and these nine were of the 
same age and had been growing under the same conditions as the seven 
which did flower. Obviously, if flowering was the direct result of drought 
or of any other climatic factor, the seven palms which were affected must 
have been in such a physiological state as to be susceptible to the influence 
while the other nine palms were not in such a state. That is, if drought is 
a factor it is a secondary one, the physiological condition of the plant being 
the primary determining factor. 
If we conclude that the ultimate cause of the time of attaining sexual 
maturity lies in the hereditary disposition of the plant, the interesting 
question arises, Why did seven of the talipots flower and nine not, since all 
in the avenue were of the same age? We can only attribute this difference 
in behavior to individual differences in the germ plasm, concerning the 
causes of which we know nothing. The age at which Corypha umbraculifera 
reaches sexual maturity is not the same in all individuals. 
The final and most convincing evidence against the hypothesis that 
drought is the direct cause of flowering, or even a factor of any great signifi¬ 
cance in the flowering of certain palms and bamboos, is the behavior of 
another talipot at Peradeniya and of a talipot and the bamboos at Buiten- 
zorg. The talipot in question at Peradeniya is one which flowered some 
years ago, in 1903 (fig. 2). For four years (1899-1902) previous to the 
flowering of this palm at Peradeniya the average annual rainfall was, in 
each of these four years, above the normal average. In 1902, the year 
immediately preceding the flowering, the total annual rainfall was approxi¬ 
mately one third above the normal average. It is quite evident that the 
flowering of this talipot can in no way be attributed to drought. 
When the many talipots in Ceylon were blossoming in 1918, the only 
old specimen of this palm in the gardens at Buitenzorg was also in flower 
(fig. 3). At Buitenzorg there is no such thing as drought. The writer was 
