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 flowering?