phragmites

Phragmites
Phragmites australis seed head in winter
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
(unranked):	Commelinids
Order:	Poales
Family:	Poaceae
Subfamily:	Arundinoideae
Tribe:	Arundineae[1]
Genus:	Phragmites
Species:	P. australis
Binomial name
Phragmites australis (Cav.) Trin. ex Steud.

Phragmites australis, the common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world. It is sometimes regarded as the sole species of the genus Phragmites, though some botanists divide Phragmites australis into three or four species and in particular the South Asian Khagra Reed (P. karka) is often treated as distinct.^[2]

Growth

Common reed commonly forms extensive stands (known as reed beds), which may be as much as a square kilometer or more in extent. Where conditions are suitable it can spread at 5 metres (16 ft) or more per year by horizontal runners, which put down roots at regular intervals. It can grow in damp ground, in standing water (up to a meter or so deep), or even as a floating mat. The erect stems grow to 2–6 metres (6 ft 7 in–19 ft 8 in) tall, with the tallest plants growing in areas with hot summers and fertile growing conditions.

The leaves are long for a grass, 20–50 centimetres (7.9–20 in) and 2–3 centimetres (0.79–1.2 in) broad. The flowers are produced in late summer in a dense, dark purple panicle, about 20–50 cm long. Later the numerous long, narrow, sharp pointed spikelets appear greyer due to the growth of long, silky hairs.

It is especially common in alkaline habitats, and it also tolerates brackish water,^[3] and so is often found at the upper edges of estuaries and on other wetlands (such as grazing marsh) which are occasionally inundated by the sea.

Common reed is suppressed where it is grazed regularly by livestock. Under these conditions it either grows as small shoots within the grassland sward, or it disappears altogether.

Taxonomy

The generally accepted botanical name of common reed is Phragmites australis (Cav.) Trin. ex Steud.. However, it is still often known as Phragmites communis Trin.; other synonyms include Arundo phragmites L. (the basionym), Phragmites altissimus, P. berlandieri, P. dioicus, P. maximus, P. vulgaris^{[clarification needed]}.

Wildlife

A previously sandy beach invaded by reeds.

Three Phragmites seedlings, A very young, C the oldest (3-4 months). Roman numerals denote different shoot generations. Sc = scutellum. From (Warming 1884^{[clarification needed]})

Reed beds

Common reed is very important (together with other reed-like plants) for wildlife and conservation, particularly in Europe and Asia, where several species of birds are strongly tied to large Phragmites stands. These include:

• Bearded Reedling (Panurus biarmicus)
• Reed Warbler (Acrocephalus scirpaceus)
• Great Bittern (Botaurus stellaris)

Invasive reeds

In North America, the status of the species was misunderstood. It was commonly considered to be an exotic species, not native but introduced from Europe; however, there is now clear evidence of the existence of Phragmites native in North America long before European colonisation of the continent. It is now known that the North American native forms of Phragmites are markedly less vigorous than European forms; the recent marked increase in Phragmites in North America may be due to a vigorous, but otherwise almost indistinguishable European form of the species, best detectable by genetic analysis. This is causing serious problems for many other North American wetland plants, including the local form of the species.^[3] Gallic acid released by Phragmites is degraded by ultraviolet light to produce mesoxalic acid, effectively hitting susceptible plants and seedlings with two harmful toxins.^[4]

Recent studies have characterised morphological variation among the introduced and native stands of Phragmites in North America. The Eurasian genotype can be distinguished from the North American genotype by its shorter ligules of up to 0.9 millimetres (0.04 in) as opposed to over 1.0 millimetre (0.04 in), shorter glumes of under 3.2 millimetres (0.13 in) against over 3.2 millimetres (0.13 in) (although there is some overlap in this character), and in culm characteristics. Recently, the North American genotype has been described as a distinct subspecies, Phragmites australis subsp. americanus Saltonstall, Peterson, and Soreng; the Eurasian genotype is referred to as Phragmites australis subsp. australis.

In Europe, common reed is rarely invasive, except in damp grasslands where traditional grazing has been abandoned.

Uses

Thatching

Reed is used in many areas for thatching roofs. In the British Isles, common reed used for this purpose is known as Norfolk reed or water reed. However "wheat reed" and "Devon reed", also used for thatching, are not in fact reed, but long-stemmed wheat straw.

Water treatment

Reed is the main wetland species used for water treatment.

Waste water from bathrooms, lavatories and kitchens is routed to an underground septic tank-like compartment where the solid waste is allowed to settle out. The water then trickles through a constructed wetland or artificial reed bed (not to be confused with the natural reed bed habitat), where bacterial action on the surface of roots and leaf litter removes some of the nutrients. The water is then suitable for irrigation or discharge to watercourses.

Other uses

Some other uses for reeds in various cultures include baskets, mats, pen tips, and a crude form of paper.^[5]

In the Philippines, Phragmites is known by the local name "tambo". Reed stands flower in December, and the blooms are harvested and bundled into brooms called "walis". Hence the common name of household brooms is "walis tambo".

In literature

One reference to reeds in European literature is Frenchman Blaise Pascal's saying that Man is but a 'thinking reed' (roseau pensant). In La Fontaine's famous fable (The Oak and the Reed, Le chêne et le roseau), the reed tells the proud oak: "I bend, and break not" ("Je plie, et ne romps pas"), before the tree's fall.

Moses was "drawn out of the water where his mother had placed him in a reed basket to save him from the death that had been decreed by the Pharaoh against the firstborn of all of the children of Israel in Egypt" (Exodus 2:10).^[6]. However, the plant concerned may have been another reed-like plant, such as papyrus, which is still used for making boats.

Reed stems in flower, in France	Reed growth in early summer	Roadside reed left from previous year, in Hungary	Reed stems in autumn, in Virginia
Common reed in winter, Sudbury, MA, USA

References

See also

• Constructed wetland
• Deben Estuary
• Reed bed
• Reed fields

External links

• Online Field guide to Common Saltmarsh Plants of Queensland
• Invading Species.com Ontario Ministry of Natural Resources and Ontario Federation of Anglers and Hunters

Wikimedia Commons has media related to: Phragmites

• Cryptic invasion by a non-native genotype of the common reed, Phragmites australis, into North America (pdf file)
• Phragmites australis swamp and reed beds. On the MarLIN website.
• Brandweiner O. et al., Phragmites australis as Alternative Fuel for Clinker Production, DeopTech 2006, Leoben, Austria