- Many, see text
Bamboos are a group of woody perennial evergreen plants in the grass family Poaceae, subfamily Bambusoideae. Some of its members are giants, forming by far the largest members of the grass family.
Bamboos are found in diverse climates, from cold mountains to hot tropical regions. They occur from northeast Asia (at 50°N latitude in Sakhalin), south throughout east Asia west to the Himalaya, and south to northern Australia. They also occur in sub-Saharan Africa, and in the Americas from the southeast of the USA south to Chile, there reaching their furthest south anywhere, at 47°S latitude. Major areas with no native bamboos include Europe, north Africa, western Asia, northern North America, most of Australia and Antarctica.
The stems, or 'culms', can range in height from a few centimeters to 40 metres, with stem diameters ranging from 1 mm to 30 cm. The stems are jointed, with regular nodes; each node bears one leaf, and may also have one to several side branches. They are thus, unlike most other grasses, extensively branched; in large-growing species a single stem may carry many thousands of branchlets.
Many of the larger bamboos are very tree-like in appearance, but perhaps illogically they are rarely called trees, despite that term being a growth form, not a botanical term. For comparison, palms, which like bamboos are monocotyledons, are equally dissimilar to other trees, yet are usually called trees.
A single stem of bamboo from an established root system typically reaches full height in just one year, but then persists for several years, gradually increasing the number of side branches and branchlets.
Some species of bamboo flower rarely, some of them only every 100 or more years. When these rare flowering species bloom, the plant can die. Furthermore, all the individuals of the species will flower at the same time in a large geographical region. This is thought to be a defence against predators of the seed, who would be unable to depend on a predictable food supply.
Many bamboos are popular in cultivation as garden plants. In cultivation, care needs to be taken of their potential for invasive behaviour. They spread mainly through their roots and/or rhizomes, which can spread widely underground and send off new culms to break through the surface. There are two patterns for the spreading of bamboo, clumping (monopodial) and running (sympodial). Clumping bamboo species tend to spread out underground slowly. Running bamboo species, however, can spread several feet a year, are considered very invasive and can cause problems by invading adjacent gardens. It is very difficult to remove bamboo without digging up the entire network of underground rhizomes, for there is no central root to destroy, and destroying the plant above ground will leave the underground rhizome system waiting until next year to send up its shoots.
One way to prevent running bamboo from taking over an area is to surround it with a physical barrier, although in order to be effective the barrier must reach down to below the depth at which the rhizomes spread, which can be several feet.
Established bamboo will send up shoots that generally grow to their full height in a single season, making it the fastest growing plant. Tales of bamboo growing 30 cm (1 foot) per day are not exaggerated; in fact the giant construction variety of bamboo has been documented as growing over a metre (4 feet) in one day. However a newly transplanted bamboo plant can take many many seasons before its shoots achieve their full potential height.
The shoots (new bamboo culms that come out of the ground) of bamboo are edible and are available in supermarkets in various sliced forms. However, the shoots of some species contain toxins that need to be leached or boiled out before they can be eaten safely.
Bamboo forms a very hard wood, especially when seasoned, making it useful for many things such as houses (in tropical climates), fences, bridges, walking sticks, furniture, food steamers, toys, construction scaffolding, hats, abaci and various musical instruments such as the shakuhachi. Modern companies are attempting to popularize flooring made of bamboo pieces steamed, flattened, glued together, finished, and cut.
Bamboo houses in Seram, Indonesia (adjacent plants are bananas
When bamboo is harvested for wood, care is needed to select mature stems that are several years old, as first-year stems, although full size, are not fully woody and are not strong.
Bamboo canes are normally round in cross-section, but square canes can be produced by forcing the new young culms to grow through a tube of square cross-section and slightly smaller than the culm's natural diameter, thereby constricting the growth to the shape of the tube. Every few days the tube is removed and replaced higher up the fast-growing culm.
Bamboo has been used to make paper in China since early times. A high quality hand-made paper is still produced in small quantities. Coarse bamboo paper is still used to make spirit money in many Chinese communities.
Bamboo's long life makes it a Chinese symbol of long life, while in India it is a symbol of friendship. Its rare blossoming has led to the flowers' being regarded as a sign of impending famine. Several Asian cultures, including that of the Andaman Islands, believe that humanity emerged from a bamboo stem. Malaysian legends include the story of a man who dreams of a beautiful woman while sleeping under a bamboo plant; he wakes up and breaks the bamboo stem, discovering the woman inside. In the Philippines, bamboo crosses are used as a good luck charm by farmers. In Japan, a bamboo forest surrounds a Shinto shrine as part of a sacred barrier against evils. Also, bamboo is considered second in the rank in the order of "Matsu (pine wood), Take (bamboo), Ume (prune)" and this order is used when ordering a sushi course or getting a room in a traditional inn.
Soft bamboo shoots, stems and leaves are the major food source of the Giant Panda of China.
There are about 90 genera and 1,000 species of bamboo. The best-known, mainly temperate genera are:
- Guadua angustifolia
- But, Paul Pui-Hay, et. al. 1985. Hong Kong Bamboos. Urban Council, Hong Kong.