Bamboo is a perennial evergreen plant in the grass family. Giant or "timber species" bamboo are the largest
members of the grass family.
Bamboo is the fastest-growing plants in the world. Certain species of bamboo have been clocked at 4 to 8 feet
in just 24 hours. Bamboos are of notable economic and cultural significance in South Asia, Southeast Asia and
East Asia, being used for building materials, as a food source, and as a versatile raw product. Bamboo has a
higher compressive strength than wood, brick or concrete and a tensile strength that rivals steel.[
There are about 1,450 species of bamboo. From cold mountains to hot tropical regions, they occur as far north
as 50°N latitude to their southernmost point at 47°S latitude. Continental Europe is not known to have any native
species of bamboo.
Unlike all trees, individual bamboo stems, or culms, emerge from the ground at their full diameter and grow to
their full height in a single growing season of three to four months. During these several months, each new shoot
grows vertically into a culm with no branching out until the majority of the mature height is reached. Then, the
branches extend from the nodes and leafing out occurs. In the next year, the pulpy wall of each culm slowly
hardens. During the third year, the culm hardens further. The shoot is now considered a fully mature culm. Over
the next 2–5 years (depending on species), fungus begins to form on the outside of the culm, which eventually
penetrates and overcomes the culm. Around 5–8 years later (species and climate dependent), the fungal
growths cause the culm to collapse and decay. This brief life means culms are ready for harvest and suitable for
use in construction within about three to seven years. Individual bamboo culms do not get any taller or larger in
diameter in subsequent years than they do in their first year, and they do not replace any growth lost from
pruning or natural breakage. Bamboos have a wide range of hardiness depending on species and locale. Small
or young specimens of an individual species will produce small culms initially. As the clump and its rhizome
system mature, taller and larger culms will be produced each year until the plant approaches its particular
species limits of height and diameter.
Most bamboo species flower infrequently. In fact, many bamboos only flower at intervals as long as 65 or 120
years. Any plant derived through clonal propagation from this cohort will also flower regardless of whether it has
been planted in a different location. The longest mass flowering interval known is 130 years, and it is for the
species Phyllostachys bambusoides. In this species, all plants of the same stock flower at the same time,
regardless of differences in geographic locations or climatic conditions, and then the bamboo dies. The lack of
environmental impact on the time of flowering indicates the presence of some sort of “alarm clock” in each cell
of the plant which 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.
One hypothesis to explain the evolution of this semelparous mass flowering is the predator satiation hypothesis
which argues that by fruiting at the same time, a population increases the survival rate of their seeds by flooding
the area with fruit, so, even if predators eat their fill, seeds will still be left over. 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. Thus the death of the adult clone is due to resource exhaustion, as
it would be more effective for parent plants to devote all resources to creating a large seed crop than to hold
back energy for their own regeneration.
Another, the fire cycle hypothesis, argues that periodic flowering followed by death of the adult plants has
evolved as a mechanism to create disturbance in the habitat, thus providing the seedlings with a gap in which to
grow. This argues that the dead culms create a large fuel load, and also a large target for lightning strikes,
increasing the likelihood of wildfire. Because bamboos can be aggressive as early successional plants, the
seedlings would be able to outstrip other plants and take over the space left by their parents.
However, both have been disputed for different reasons. The predator satiation hypothesis does not explain why
the flowering cycle is 10 times longer than the lifespan of the local rodents, something not predicted. The
bamboo fire cycle hypothesis is considered by a few scientists to be unreasonable; they argue that fires only
result from humans and there is no natural fire in India. This notion is considered wrong based on distribution of
lightning strike data during the dry season throughout India. However, another argument against this is the lack of
precedent for any living organism to harness something as unpredictable as lightning strikes to increase its
chance of survival as part of natural evolutionary progress.
The mass fruiting also has direct economic and ecological consequences, however. The huge increase in
available fruit in the forests often causes a boom in rodent populations, leading to increases in disease and
famine in nearby human populations. For example, devastating consequences occur when the Melocanna
bambusoides population flowers and fruits once every 30–35 years around the Bay of Bengal. The death of the
bamboo plants following their fruiting means the local people lose their building material, and the large increase in
bamboo fruit leads to a rapid increase in rodent populations. As the number of rodents increases, they consume
all available food, including grain fields and stored food, sometimes leading to famine. These rats can also carry
dangerous diseases, such as typhus, typhoid, and bubonic plague, which can reach epidemic proportions as the
rodents increase in number. The relationship between rat populations and bamboo flowering was examined in a
2009 Nova documentary "Rat Attack".
In any case, flowering produces masses of seeds, typically suspended from the ends of the branches. These
seeds will give rise to a new generation of plants that may be identical in appearance to those that preceded the
flowering, or they may produce new cultivars with different characteristics, such as the presence or absence of
striping or other changes in coloration of the culms.
Several bamboo species are never known to set seed even when sporadically flowering has been reported.
Bambusa vulgaris, Bambusa balcooa and Dendrocalamus stocksii are common examples of such bamboo.
Many tropical bamboo species will die at or near freezing temperatures, while some of the hardier or so-called
temperate bamboos can survive temperatures as low as −29 °C (−20 °F). Some of the hardiest bamboo species
can be grown in places as cold as USDA Plant Hardiness Zones 5–6, although they typically will defoliate and
may even lose all above-ground growth, yet the rhizomes will survive and send up shoots again the next spring.
In milder climates, such as USDA Zone 8 and above, some hardy bamboo may remain fully leafed out year-