102 AMERICAN JOURNAL OF BOTANY [Vol. io, 
there during the so-called dry season and rain fell in torrents nearly every 
afternoon. While the dry season characteristic of Java as a whole is 
sometimes more or less evident at Buitenzorg, it never assumes the pro¬ 
portions of a drought. The avenue of talipot palms at Peradeniya and 
others on the island of Ceylon which flowered in 1918 had been subjected 
to a prolonged dry season immediately preceding the time of flowering and 
to several severe droughts during their thirty-eight years of existence. 
The Corypha at Buitenzorg, on the other hand, had been drenched in rain 
nearly every day of its life; yet on both islands the palms flowered in the 
same year. 
It would be interesting to know if the flowering of the Buitenzorg 
talipot commenced in the same month, June, 1918, as did that of the Ceylon 
palms. One would be inclined in such a case to suspect the presence of 
some meteorological influence of wide distribution, if one is willing to place 
any faith in an external stimulus as an influencing factor of even secondary 
importance. That the palms in Ceylon and at Buitenzorg did flower at 
very nearly the same time of year is evident from the Peradeniya data and 
from my observations in Java. (Unfortunately no records are kept of the 
date of flowering of plants in the Buitenzorg Gardens.) The palms at 
Peradeniya flowered in June, 1918, fruited during the latter part of 1919 
and early in 1920, and died in 1921. The Corypha at Buitenzorg had just 
dropped its fruit when I first saw it in August, 1920 (fig. 3). 
What is true of the talipot palms at Peradeniya and at Buitenzorg is 
also true of the bamboos at the two gardens. At the time of my stay in 
Buitenzorg, seven species, out of a total of twenty-four in the Gardens, were 
in flower. One of these species was Dendrocalamus giganteus , which was in 
heavy flower. The species is the same as that of one of the bamboos which 
flowered at Peradeniya in 1918. This D. giganteus and the six other 
flowering species of bamboo at Buitenzorg had not been subjected to a 
drought nor even to a characteristic tropical dry season. 
We are, it seems to me, forced to conclude that the ultimate cause of 
gregarious flowering in bamboos of long life cycle, in particular Chusquea 
abietifolia , Bambusa arundinacea , B. polymorpha, Dendrocalamus giganteus , 
and D. strictus, and in the talipot palm, Corypha umbraculifera , is not 
drought. If drought is at all an influencing factor, then its effect must be 
relatively slight. While the simultaneous attaining of sexual maturity of 
three widely differing genera of plants, all of whose life periods are of great 
length, is an event of such unusual occurrence that one is inclined to wonder 
if there might not; be an external stimulus which is responsible, yet if some 
such environmental cause does exist we are totally ignorant of what it 
may be. 
The Rhythm in the Sexual Cycle of Bamboos 
Evidence of a different kind, which stands in opposition to the assump¬ 
tion that the attaining of sexual maturity of bamboos of long life cycle is 
