98 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
The sexual cycles of D. arundinacea and D. stric us are about thirty-two 
years in length. Bambusa polymorpha is known to have a very long life 
period. I know of no authentic record of two successive flowering dates. 
In the Indian Forester for 1903 appears the statement that “the last 
recorded flowering of the Kyathaung was . . . in 1853“ (13, p. 244). The 
flowering of this bamboo, Bambusa polymorpha , was expected to recur 
shortly after 1883 on the general belief that the life of bamboos is about 
thirty yeg.rs. The flowering of B. polymorpha in the forests of Burma has 
not yet occurred. Certain “signs” of an expected flowering have from 
time to time been seen. These signs refer to the well-known habit which 
bamboos have of producing no new shoots in the year of flowering. 
The bamboo forests of B. polymorpha in Burma may be reckoned by 
hundreds if not by thousands of square miles. In this extensive region of 
bamboos there have been, since 1883, one or two false alarms of gregarious 
flowering when a clump or two has blossomed. In 1918 and 1919 an area 
of several hundred acres in two or three distinct but neighboring blocks in 
the Tharrawaddy Division flowered gregariously. 4 (The plants of B. poly¬ 
morpha were at this time sixty*five years of age.) This was thought to be 
the forerunner of a general flowering, since the flowering of odd clumps is 
considered to be an indication that the flowering of the whole area is im¬ 
minent. But so far no general flowering has taken place. 
During their sixty-eight years of existence the bamboos of these forests 
have endured many droughts which apparently have had no effect whatso¬ 
ever on the sexual maturity of the plants. For at least the latter half of 
their life the bamboos must certainly have been mature enough to respond 
to an external stimulus, if this stimulus is of such a nature as to exercise 
any prominent influence on the sexual life of the plants. 
We have so far seen, first, that bamboos of long and rhythmic life 
Cycles reach sexual maturity when experiencing only the normal annual 
dry season of the tropics; and second, that other bamboos of long periodicity 
have for sixty-eight years failed to attain sexual maturity even though they 
have experienced many seasons of both normal dry weather and drought. 
There now remain to be considered those instances in which flowering takes 
place in the entire absence not only of drought but even of a typical tropical 
annual dry season. 
The most striking instance of this is the behavior of the bamboos at 
Buitenzorg, Java, where droughts are unknown and dry seasons are few 
and far between. Before passing on to the Buitenzorg data it will be 
interesting to consider in more detail the similar case of the climbing bam¬ 
boo, Chusquea abietifolia , already referred to. This bamboo, a slender 
scandent form, occurs in great abundance throughout the mountains of 
Jamaica. The high altitude regions of Jamaica receive abundant moisture 
4 I am indebted to H. R. Blanford, Esq., 0 . B. E., Government silviculturist at May- 
myo, Burma, for this information. 
