102 AMERICAN JOURNAL OF BOTANY [Vol. 10, 



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 192 1. 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 gigantens, 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. gigantens 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 timbraculifera, 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 



