Bamboos are a group of woody perennial evergreen plants in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. 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.
Biology
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 rarely flower, some of them only every 10-100 or more years. Some of these species are monocarpic, the plant dying after the seed matures. 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 behavior. 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 underground slowly. Running bamboo species are highly variable in their tendency to spread; this is related to both the species and the soil and climate conditions. Some can send out runners several metres a year, while others can stay in the same general area for long periods. If neglected, they can be invasive over time and can cause problems by moving into adjacent areas. Once established as a grove, it is difficult to completely remove bamboo without digging up the entire network of underground rhizomes. If bamboo must be removed, an alternative to digging it up is to cut down the culms, and then repeatedly mow down new shoots as they arise, until the root system exhausts its energy supply and dies. The reputation of bamboo as being highly invasive is often exaggerated, and situations where it has taken over large areas is often the result of years of untended or neglected plantings over a number of years.
There are two main ways to prevent the spread of running bamboo into adjacent areas. The first involves surrounding it with a physical barrier, usually a special, high density, plastic roll material made for this purpose; this is placed in a 60-90 cm (2-3 feet) deep ditch around the planting, and angled out at the top to direct the rhizomes to the surface. The second method is rhizome pruning, which involves taking a sharp spade and cutting down into the ground 30 cm (1 foot) all along the perimeter that is to be maintained. The root system is generally very close to the surface, so, if rhizome pruning is done twice a year, it will sever most, if not all, of the new growth. Since the new roots are dependent on older parts of the root system for nourishment, anything beyond the shovel cut will die in the ground and be unable to reestablish itself.
Established bamboo will send up shoots that generally grow to their full height in a single season, making it the fastest growing woody plant. Several subtropical bamboo species can grow 30 cm (1 foot) per day, with some species having been documented as growing over 100 cm in one day. For the species most widely cultivated in gardens, 3-5 cm per day is more typical. A newly transplanted bamboo plant can take 1-2 years before it sends up new shoots (culms) and will have many seasons of “sizing up” before new shoots achieve the maximum potential height for that species.
Uses
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.
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.
Cultural aspects
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.
From Wikipedia, the free encyclopedia.
