348 SEIFRIZ: THE TALIPOT PALM AT PERADENIYA, CEYLON 
possibility of climatic influences having a slight but appreciable 
effect on the exact time of blossoming. It is an old theory that 
favorable environmental conditions tend to produce purely 
vegetative growth while unfavorable conditions tend to bring 
on reproductive activity. How much truth there is in this theory 
it is difficult to say. What may be unfavorable for one species 
may have no effect on another adapted to the same general 
surroundings as the first. If it is true that drought is an unfavor- 
able condition which tends to bring on reproductive activity 
in plants, then it is possible that as plants of long life cycle 
approach their normal time of flowering, the occurrence of a 
severe drought shortly before this time would somewhat hasten 
the coming of the reproductive period. 
One final bit of evidence which seems to utterly preclude 
the possibility of drought being the primary cause of gregarious 
flowering in plants is, that this flowering is rhythmic in certain 
species. This is true in some bamboos. Thus, in Bambusa arun- 
dinacea three successive flowering periods in India have been 
recorded, making the life cycle one of 32 years (7). The flowering 
of Phyllostachys puberula is recorded in old manuscripts of China 
and Japan as occurring every 60 years (5). The records, some- 
what incomplete, go back to the year 292 A.D. 
There is little reason to doubt the fact that flowering in 
certain bamboos is rhythmic. There is, on the other hand, no 
conclusive evidence to support the presence of rhythmic changes 
in climate which are commensurable in length with the life cycle 
of certain palms and bamboos. Meteorologists are generally 
‘of the opinion that climatic cycles of some 30 or more years 
duration do not exist. The only approximate climatic cycle of 
which we can be reasonably certain is that which corresponds 
to the sun spot cycle. This is greatly variable, with an eleven 
year period and probably other periods, both shorter and longer 
(3). The variations which this cycle occasions are negligible, 
being in temperature of the order of 1° C. between extremes, 
_and often less. The other climatic changes, such as changes of 
precipitation, wind velocity, and the like, which are consequences 
of the temperature change, are correspondingly small. That 
there is much evidence (for example, in growth rings of old trees) 
that appreciable climatic changes of many years duration have 
occurred within historic times, is true, but these changes do not 
