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019  Phragmites australis (Cav.) Trin

Graminaceae

Nome comune: Cannuccia di palude

Phragmites, the Common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world. Phragmites australis is sometimes regarded as the sole species of the genus Phragmites, though some botanists divide Phragmites australis into three or four species. In particular the South Asian Khagra Reed -Phragmites karka - is often treated as a distinct species.[2] In North America, the status of Phragmites australis was a source of confusion and debate. It was commonly considered an exotic species and often invasive species, introduced from Europe. However now with evidence of the existence of Phragmites as a native plant in North America long before European colonization of the continent[citation needed]. It is now known that the North American native forms of P. a. subsp. americanus are markedly less vigorous than European forms. The recent marked expansion of Phragmites in North America may be due to the more vigorous, but otherwise almost indistinguishable European subsp. australis , best detectable by genetic analysis.[citation needed] Phragmites australis subsp. australis is causing serious problems for many other North American hydrophyte wetland plants, including the native Phragmites australis subsp. americanus. 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][5] Phragmites australis, Common reed, commonly forms extensive stands (known as reed beds), which may be as much as 1 square kilometre (0.39 sq mi) 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 1 metre (3 ft 3 in) 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 a halophyte, especially common in alkaline habitats, and it also tolerates brackish water,[4] 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. In Europe, common reed is rarely invasive, except in damp grasslands where traditional grazing has been abandoned. Phragmites australis is one of the main wetland plant species used for phytoremediation water treatment. Waste water from lavatories and greywater from 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, where bioremediation bacterial action on the surface of roots and leaf litter removes some of the nutrients in biotransformation. The water is then suitable for irrigation, groundwater recharge, or release to natural watercourses. 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. Numerous parts of Phragmites can be prepared for consumption. For example, the young stems "while still green and fleshy, can be dried and pounded into a fine powder, which when moistened is roasted [sic] like marshmallows." Also, the wheat-like seeds on the apex of the stems "can be ground into flour or made into gruel." Rootstocks are used similarly.[8] When Midas had his ears transformed into donkey's ears, he concealed the fact and his barber was sworn to secrecy. However the barber could not contain himself and rather than confiding in another human, he spoke the secret into a hole in the ground. The reeds that grew in that place then repeated the secret in whispers. 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).[9]. However, the plant concerned may have been another reed-like plant, such as papyrus, which is still used for making boats. One reference to reeds in European literature is Frenchman Blaise Pascal's saying that Man is but a 'thinking reed' — roseau pensant. In Jean de La Fontaine's famous fable The Oak and the Reed — Le chκne 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."