Feb., 1923] SEIFRIZ — CAUSES OF GREGARIOUS FLOWERING IO3 



greatly influenced by environmental factors, are the observations made in 

 India which have twice established the cycle of Bambusa arundinacea to be 

 exactly thirty-two years. This bamboo flowered in Cisgangetic India (the 

 west coast) in 1804, 1836, and 1868 (18, p. 251). It is of interest to note 

 here that the life cycle of Chusquea abietifolia, quite a different type of 

 bamboo, is also about thirty-two years (recorded as thirty-three years) (20). 



Less definite, and tending more strongly to support the supposition that 

 the exact time of flowering may possibly be somewhat advanced or delayed 

 by external factors, are the interesting data of Kawamura who states that 

 the flowering of Phyllostachys puberula has been recorded in old manuscripts 

 of China and Japan as occurring in the following years: 292, 813, 931, 

 1 1 14, 1247, 1666, 1786, 1848, and 1908 (14). It will be noted that most of 

 the intervals between these dates are either about sixty or multiples of 

 sixty years. 



One can, of course, fall back upon the assumption that climatic cycles 

 of rhythmic periodicity also occur and that these determine the regularity 

 of the sexual functioning of bamboos. While certain meteorological phe- 

 nomena take place rhythmically, e.g., the annual seasonal cycle, it is as 

 yet by no means well established that climatic changes of many years' 

 duration are periodic, and there is little evidence that droughts occur 

 rhythmically. 



The evidence so far presented is overwhelmingly against the belief that 

 drought is either the cause of gregarious flowering or that it has any marked 

 influence on reproduction in bamboos. That climate may possibly exert 

 some slight effect on flowering is not, however, to be emphatically denied. 

 While there is little and only indirect evidence in support of this possibility, 

 it is quite conceivable that as a plant of long sexual cycle nears its time of 

 reproduction, unfavorable conditions may hasten the sexual process some- 

 what. Such a supposition would assist in explaining so remarkable a 

 concurrence of simultaneous flowering as occurred in the Peradeniya 

 Gardens in 1918, though here we must presuppose some climatic factor 

 other than drought. 



Depletion of nourishment and injury are two other factors external to 

 the plant which have been advanced as causes of flowering in bamboos. 

 One of these, injury, cannot be regarded as a natural cause of flowering. 

 It has, therefore, no direct bearing on our problem, but it is of interest, and 

 we shall consider it. 



Depletion of Nourishment as a Cause of Flowering in Bamboos 



The Japanese worker Hori (8) is of the opinion that flowering in bamboos 

 is a "physiological disease." This opinion is in contradiction to that of 

 his fellow countryman Kawamura, who attributes the cause of flowering to 

 the hereditary disposition of bamboos. 5 (The observations of Kawamura 



5 I am indebted to Professor Manabu Miyoshi for calling my attention to work done 

 in Japan on the flowering of bamboos. 



