Common Name: Giant Reed

General Information

Giant reed is a large, clump-forming, bamboo-like, perennial grass with elongated rhizomes. It produces erect, more or less woody, thin-walled stems 200 - 600cm tall.
The plant has a wide range of applications and is often cultivated for use in basket making and to control soil erosion. The plant is often also cultivated in warm temperate to tropical areas as an ornamental[, ].
Widely grown as an ornamental, the plant can easily escape from cultivation and become naturalized. T has been declared 'Invasive' in many countries. Once established, it can form huge colonies, sometimes covering hundreds of acres. It is highly flammable and resprouts quickly after burning. Fires help transform communities of native plants into solid stands of giant reed, changing riverbank forests from flood- to fire-defined habitats[].

Known Hazards

None known

Botanical References

,

Range

Arabian Peninsula through western and central Asia to China, Japan, India, Myanmar to Malaysia and Indonesia. Widely naturalized elsewhere.

Habitat

Ditches, riversides and marshland[, ]. Often found on sand dunes near seashores[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Perennial
Height	4.00 m
Pollinators	Wind
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

The plant is adapted to tropical, subtropical and warm temperate climates of the World. It is found in climates ranging from cool temperate wet; through tropical dry; to wet forest[]. The plant is reported to tolerate annual precipitation in the range of 300 - 4,000mm, an average annual temperature range of 9 - 28.5°c[].
Prefers a moist fertile soil in a sunny sheltered position, preferably by water[, , ]. Said to tolerate all types of soils, from heavy clays to loose sands and gravelly soils[]. It tolerates some salt[]. Tolerates a pH in the range 5.0 to 8.7[].
It grows best along river banks and in other wet places, and is best developed in poor sandy soil and in sunny situations. Plants can be grown as a specimen in lawns etc, succeeding in quite coarse grass[]. Plants are succeeding in a site that is very exposed to maritime winds at Rosewarne in Cornwall[].
Extensively cultivated in S. Europe for basket making etc[].
Plants rarely if ever flower in British gardens233].
Members of this genus are rarely if ever troubled by browsing deer[].

Edible Uses

Rhizome - raw or cooked[]. The rhizome can be dried and ground into a powder to make bread, usually in conjunction with cereal flours[, ]. It can also be roasted or boiled[].

Leaves - cooked as a potherb[]. They are very bitter[]. The young shoots are used[].

Medicinal

The root is diaphoretic, diuretic, emollient and galactofuge[]. An infusion is said to stimulate menstrual discharge and diminish milk flow[, ]. A paste of the root is applied to the forehead to treat headaches[]. Isolated alkaloids have been experimentally shown to raise the blood pressure and contract the intestine and uterus[]. The rhizome or rootstock is used in the treatment of dropsy. Boiled in wine with honey, the root or rhizome has been used for treating cancer[].

The plant contains the alkaloid gramine. This is said to be a vasopressor, raising the blood pressure in dogs after small doses, causing a fall in larger doses[].

The stems have been used as splints for broken limbs[].

Agroforestry Uses:

Plants are grown alongside irrigation canals to check soil erosion[].
The plant can be grown as a windbreak screen[, ]. If cut down, the culms branch and in this form the plants can be used as a hedge[].

Other Uses

Brooms are made from the terminal panicles[].

The leaves can be woven into mats etc, whilst the split and flattened stems are used to make screens, walls of houses etc[, , , ].

A yellow dye is obtained from the pollen[].

The stems of the plant have a multitude of applications. They are used as plant supports for vines and other climbing plants[, , ] and to make clarinets, bag-pipes etc[, , ]. They are also used as pipe stems[], for roofing[], to make screens, walking sticks and in basketry[, ]. They are used to make the reeds of clarinets and organ pipes[]. The stems can be harvested as desired at any time of the year[].

The fibre from the stems can be used to make a high quality paper[, ]. Annual yields of up to 34 tonnes per hectare of fibre can be obtained, though new plantings take 3 - 5 years to attain these yields[]. Even in drought conditions, yields of 19 tonnes per hectare have been attained[]. This plant is currently (1995) under investigation at Rosewarne in Cornwall as a potential commercial paper crop for small-scale industries in SW. England[].

Because of rather high yields from natural stands, the plant has been suggested as a source of biomass for energy production[, ]. Dry cane yields of ca 10, , and 20 tonnes per hectare were reported respectively from infertile, partly fertile and fertile soils[]. According to the phytomass files annual productivity ranges from 10 to 59 tonnes per hectare, the latter figure from Westlake's (1963) estimate of 57 - 59 tonnes[]. In addendum, Westlake cites evidence that Arundo donax can produce 40–75 MT/ha/yr. In warm temperate and tropical regions. Early vegetative growth has ME (metabolizable energy) of 2.22 megacalories/kg DM, while hay has an ME of only 1.37 (Gohl, 1981). Such annual productivity, if sustainable, makes this a notable energy candidate, especially when one considers the energy as a by-product, with leaf protein and potential pharmaceutical as primary products[].

A particular type of cellulose is obtained from the plant[]. In Italy, the plant is used in the manufacture of rayon[].

Propagation

Seed - surface sow in a greenhouse in late winter to mid spring. Stand the pots in about 3cm of water to keep the soil moist until the seed germinates. It usually germinates in 1 - 3 months at 15°c[]. When large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Once they are 20cm or more tall, plant them out into their permanent positions in late spring or early summer.
Division in spring[]. Whilst large divisions can be planted out direct into their permanent positions, we have found that it is best to pot the divisions up and keep them in light shade in a greenhouse until they are rooting away well.
Stem cuttings, placed in water, root easily[].