The flowering of bamboos is an intriguing phenomenon, because it is a unique and very rare occurrence in the plant kingdom. Most bamboos flower once every 60 to 130 years. The long flowering intervals remain largely a mystery to many botanists.
Bamboo flowering in spring in a garden in Roskilde, Denmark.
These slow flowering species exhibit another strange behavior — they flower all at the same time, all over the world, irrespective of geographic location and climate, as long as they were derived from the same mother plant. Most bamboos are exactly that — they are ‘division’ taken from the same mother plant at some point. These divisions were re-divided over time and shared across the world. Although the divisions are now geographically in different locations, they still carry the same genetic makeup. So when a bamboo plant in, say, North America flower, the same plant in Asia will do the same at roughly the same time. It is as if the plants carry an an internal clock ticking away until the preset alarm goes off simultaneously. This mass flowering phenomenon is called gregarious flowering.
According to one hypothesis, mass flowering increases the survival rate of the bamboo population. The hypothesis argues that by flooding the area with fruit, there will still be seeds left over even if predators eat their fill. By having a flowering cycle longer than the lifespan of the rodent predators, bamboos can regulate animal populations by causing starvation during the period between flowering events. The hypothesis still does not explain why the flowering cycle is 10 times longer than the lifespan of the local rodents.
Bamboo flowers and fruit.
Once a bamboo species has reached its life expectancy, had flowered and produced seeds, the plant dies, wiping out entire swaths of forests over a several year period. One theory is that seed production requires an enormous amount of energy which stresses the bamboo plant to such an extent that they actually die. Another theory suggests that the mother plant dies to make room for the bamboo seedlings.
The mass flowering events also attract predators, mainly rodents. The sudden availability of fruits in huge quantities in the forest brings in a tens of millions of hungry rats who feed, grow and multiply at alarming rates. After they devour the bamboo fruit, the rats start consuming crops — both stored as well as on fields. A bamboo flowering event is almost always followed by famine and disease in nearby villages. In the northeastern India's state of Mizoram, the dreaded event occurs almost like clockwork every 48 to 50 years, when the bamboo species Melocanna baccifera flowers and fruits. The phenomenon, which occurred last in 2006 to 2008, is known in the local language as mautam or "bamboo death."
A black rat munches on corn in a field near Zamuang village in northeastern Mizoram.
Children captures rats after a bamboo flowering season in Burma.
The Fargesia nitida, in flower, once in 120 years.