Bamboo Flowers: Plant & Species Understanding

The bamboo flower is a rare phenomenon that takes place once in every 60 to 120 years. The flowers, however, aren’t spectacular in any sorts, but the flowering intervals are what make the flowering pattern a mystery and quite an intriguing occurrence even for the botanists.

About Bamboo Plant

Bamboos belong to the grass family, Gramineae, the largest flowering plant family. Bamboos share this group with well-known domesticated grains such as rice, wheat, maize, oats and barley.  Asia has an unexplained affinity with

Bamboo Species worldwide

There are around 1200 bamboo species occurring worldwide. India has an abundant bamboo resource including 138 species spread among 24 genera, of which 3 genera are exotic and others are indigenous. Manipur alone has 53 species of bamboo while Arunachal Pradesh has 50 species.

Besides, it is the flowering pattern that varies from a species to another and which, botanist community can’t seem to wrap its head around.  A bamboo flower can show gregarious flowering, annual flowering or sporadic flowering.

Gregarious bamboo flowering

It is one of the most impressive flowering patterns exhibited by a bamboo plant. It happens when the entire population of bamboo starts flowering at once. This could happen at any interval between 60 to 120 years but whenever it takes place, it will happen simultaneously. It is a genetic thing and wired into each species. Bamboo flowering happens when a plant reaches towards the end of its life expectancy. A gregariously growing bamboo flower spends the entire source of energy and effort into growing flowers and then, seeds. This gregarious habit of flowering exhausts the plant and its life. A gregarious flowering habit is exhibited by bamboo plants of the same species all over the world irrespective of their geographical location. Since a bamboo plant is essentially a simple division of the mother plant, they inherit a more or less similar genetic markup.  The botanists are of opinion that the rhizomes in bamboos have a silent memory of a biological clock that ticks all the plants into flowering simultaneously and commit a ‘mass suicide’.

Sporadic bamboo flowering

A sporadic bamboo flowering takes place when a bamboo flowers intermittently and not on a mass scale. It is often induced by environmental factors and not genetically. The flowering doesn’t impact the parent plant.

Annual bamboo flowers:

Not a natural and quite a rare incidence, bamboo flowering often happens in a localized area and annually. In such a case, bamboo plants don’t even die after flowering.

In North-East India, where bamboo plants are found in abundance, the flowering is considered a bad omen especially, when it prompts an increase in the population of rodents. It is believed that bamboo flowers come along with the hints of famine and natural calamities.  The Mizoram District Council cautioned the Indian government of an eventuality of famine due to bamboo flowering and increase in the rodent population in the state in the year 1958. The Indian government, however, rejected the claims of famine and financial grant on unscientific grounds, but had to take a step back when the state faced a year-long drought and famine in the year 1959.

And it is not a new-found belief either. The traces of bamboo flowering bringing upon the curse of ruins can be found in Mahabharata too. When the evil king Jayadrath abducted Draupadi, she cursed the king that like bamboo brings forth ruin and destruction by blooming, he has brought instant destruction himself with this abduction.

However, this connection between bamboo flowering and calamities is still an unsolved mystery for the botanists.

Northeast India supports 63 bamboo species, which are an integral part of the social, cultural and economic life of the people. There are about 1500 documented traditional uses of bamboo from cradle to coffin.
Bamboo uses Bamboo shoots and seeds provide food for the people, bamboo st

Bamboo uses Bamboo shoots and seeds provide food for the people, bamboo stems and leaves provide forage for livestock. People fashion bamboo into hats, baskets, toys, musical instruments, furniture, chopsticks, paper, and weapons.

Bamboo stems are used as fuel wood and to build houses, fences, tools and field implements. Workers scale bamboo scaffolding to construct the tallest buildings in Asia. These flimsy-looking structures are models of resilience, merely swaying in typhoons that can collapse steel frameworks.

A secretion of bamboo, a fine, siliceous matter, called 'tabasheer', found in the stem of bamboos like Phyllostachys bambusoides, is used in Ayurvedic medicines as a cooling tonic, to treat cough and asthma and even as an aphrodisiac.

Culturally too, bamboos are close to the tribal people. People in Assam are careful about not cutting the bamboo on a full moon day or on a Saturday or Tuesday. A flute called 'eloo', made from the bamboo species, Dendrocalamus tulda, is played by the priest during the 'Dree festival' to drive away evil spirits.

Bamboo is also used in soil conservation. The bamboo plant has an underground rhizome and root system. Above the ground, the aerial portion of the bamboo plant has the shoot system, which consists of the stem, branches, leaves and the inflorescence or bunches of flowers.

Bamboos exhibit monocarpic flowering behavior. This means the bamboo dies after flowering. Like other grass, bamboo flowers are tiny and borne on compound inflorescences. Fertilization takes place after pollination and results in the formation of the seed.

Bamboo flowering

Bamboo flowering is a peculiar phenomenon. Bamboos grow vegetatively for a species-specific period before flowering, seeding and dying. Most bamboo plants flower only once in their life cycle. Some species of bamboo flower only once every 40 to 50 years.
Based on this flowering behaviour, bamboos can be classified into three groups. Those bamboo species that flower annually or nearly so, bamboos with gregarious and periodic flowering and bamboos with irregular flowering patterns. Most woody bamboos are semelparaous, flowering gregariously, seeding at long intervals of many years and dying thereafter. The seeds thus produced after long intervals have an extremely short life. The time interval between two successive flowerings is species specific.

In Schizostachyum elegantissimum , (a Javanese species), and Arundinaria wightiana, the period is three years. In Phyllostachys bambusoides , a Chinese species, it is 120 years while Bambusa vulgaris has a cycle of 150 years. The next bamboo flowering in northeast India is expected around year 2003-04.The mysterious pattern of bamboo flowering does not fit within the parameters of popular flowering theories in which environmental factors such as photoperiod, temperature and stress plays an important role. The en masse post-flowering death of bamboos has disastrous consequences, both ecological and economical.

The flowering and seeding at long intervals makes the propagation of bamboos through seeds and improvement by hybridisation difficult. It also threatens wild life, in particular the Giant Panda in China, which lives almost exclusively on bamboo shoots.

Considering the intimate relationship between bamboos and the Asian people, the government of India is, for once, taking the phenomenon of bamboo flowering seriously.

Bamboo flowering safeguards

The Planning Commission is working on an emergency plan to combat the likely consequences of bamboo flowering, expected around 2003-04, especially in Mizoram, where 49 percent of the geographical area is covered by bamboo plants.
A bamboo policy, the first of its kind in the country, is being formulated for the state of Mizoram. This would be a working plan to tackle issues like bamboo harvesting. The union government has also directed the state administration to increase food stocks and to store these provisions in rodent-proof silos.

Mizoram too, is taking preparatory measures. It has suggested cutting down bamboo plants, which will be economically exploited. The Planning Commission has sanctioned Rs 4 crore to establish a bamboo-processing unit.

To combat the menace of rats following bamboo flowering, the local administration plans to initiate offering a monetary reward for every rat killed. Similar incentives in the past resulted in villagers killing more than 2.5 million rats annually at the peak of flowering.

Officials are also debating measures, such as replacing flowering varieties of bamboo with non-flowering ones. Botanists, however, believe that the only way to avert famines, associated with bamboo flowering, is to teach farmers to plant crops that rats do not eat, such as ginger and turmeric, during the periods when vast fields of bamboo are expected to flower.

Whether these measures will work, only time will tell. Ref: See Here

Bamboo Flowering Habits

Is it true that flowering bamboo always dies after seed setting? The short answer to this question is: usually yes, but not always...

When discussing bamboo it is important to understand that we can't generalize, because there are over 1500 different bamboo species known to date which all have different flowering habits and flowering intervals. Furthermore, there does not exist much scientific evidence and study about why and when bamboo flowers, mainly because the flowering intervals of bamboo can be several decades apart.

While the vast majority of herbaceous bamboos flower annually, most of the woody bamboos flower very infrequently. In fact, many bamboos only flower once every 20 to 120 years and may die in part or completely due to some possible causes which I'll discussed in more detail later.

There exist 3 types of flowering in bamboo which largely depend on species and circumstances:

  1. Continuous Flowering
  2. Sporadic Flowering
  3. Gregarious Flowering

1. Continuous Flowering

Continuous or annual flowering happens with most herbaceous bamboos and in some cases also with woody bamboos (Schizostachyum). Some species keep flowering year after year without any effect on the plant itself, although the produced seeds are rarely viable.

Continuous flowering may also occur in different individual plants of a forest over different periods of time, with not more then one or two month intervals. It is possible to find year-round flowering bamboos in a forest but without causing vegetative delays much less death of the stands.

2. Sporadic Flowering

Sporadic flowering bamboo only occurs on individual stems (culms) of the same clump in a forest. As the name suggests, there is very little pattern to this type of flowering and it seems that it may be induced by environmental factors such as drought or cold instead of genetics.

Many species of bamboo, including Guadua angustifolia, may flourish both gregariously and sporadically. When sporadic flowering occurs on individual culms, the plants very rarely die but most of the seeds aren't viable either.

Adverse Conditions:

It has been noted that severe attacks of pests or disease, injury, malnutrition, or long periods of prolonged droughts and floods coincide with the presence of flowering in grooves that were under these circumstances.

These adverse causes inevitably produce reactions and mechanisms in the plants which leads them to flower with the objective to preserve the species. The seeds are then utilized as a unique system of self-perpetuation. Sporadic flowering can also occur when bamboo forests or plantations are heavily exploited.

3. Gregarious Flowering

Most woody bamboo species are subject to gregarious flowering which means that all plants of a particular species flower at the same time, regardless of differences in geographic locations or climate conditions, and then die a few years later. Intervals in the gregarious flowering cycle varies depending on the species, but in general bamboo flowering intervals can be as long as 20-120 years.

In other words, when a certain bamboo species starts to flower gregariously, they do this all over the world for a several year period until the entire forest has died. In some species, only the bamboo stems die, while rhizomes become activated again to start the natural regeneration of the species. However, this happens very rarely and is rather the exception than the rule.

Gregarious flowering often happens in different stages because mature stems start to produce seeds first. When the seed ripen and eventually fall off, the bamboo plant looses all its leaves and the culm starts to dry up from top to bottom until it finally dies. Every bamboo forest contains culms in different stages of development, therefore this entire process can take several years (3-7 years) until the forest has completely died.

Gregarious flowering is easily observable when it happens because of all the dried bamboo stems (straw like color) and the thousands of spikes in their branches. These spikes bare the seeds which are usually very similar in appearance to rice, wheat or barley.

What causes gregarious bamboo flowering?

Unlike sporadic flowering, gregarious flowering isn't triggered by environmental aspects, which leads us to believe that there must exist some sort of genetic alarm clock in each bamboo cell that signals the diversion of all energy to flower production and the cessation of vegetative growth. This mechanism, as well as the evolutionary cause behind it, is still largely a mystery. Apparently, once a particular species reaches its life expectancy, it will start to flower which is then followed by the development of seeds.

Why bamboo dies after flowering?

The 2 most probable explanations for why bamboo dies after flowering (there exist many theories) is that seed production requires an enormous amount of energy which stresses the bamboo plant to such an extent that it will actually die. A second explanation could be that the mother plant is creating an optimal environment for its seedlings to survive. In other words when the mother plant dies, the bamboo seedlings will have full access to water, nutrients and sunlight that would otherwise be used by the mother plant.

Consequences of gregarious flowering

The mass flowering of bamboos and consequential seed setting also have economic and ecological consequences. The huge amount of seeds in forests attract large populations of rats and other rodents which may consume all available food crops and may cause severe spread of diseases in surrounding villages. Furthermore, when bamboo stems die, local people lose access to vital building material for their homes and agricultural activities.

Various methods have been tested to revive flowering bamboo but only a few have been effective in some cases, many have not. Much more study needs to be done, but until bamboo reveals some of its secrets, the mystery will remain...