Phragmites australis
Phragmites australis, known as the common reed, is a broadly distributed wetland grass growing nearly tall. Taxonomy. Recent studies have characterized morphological distinctions between the introduced and native stands of "Phragmites australis" in North America. The Eurasian phenotype can be distinguished from the North American phenotype by its shorter ligules of up to as opposed to over , shorter glumes of under against over (although there is some overlap in this character), and in culm characteristics. Ecology. Growth and habitat. "Phragmites australis", common reed, commonly forms extensive stands (known as reed beds), which may be as much as or  more in extent. Where conditions are suitable it can also spread at 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 or so deep, or even as a floating mat. The erect stems grow to tall, with the tallest plants growing in areas with hot summers and fertile growing conditions. The leaves are long and broad. The flowers are produced in late summer in a dense, dark purple panicle, about long. Later the numerous long, narrow, sharp pointed spikelets appear greyer due to the  growth of long, silky hairs. These eventually help disperse the minute seeds. It is a helophyte (aquatic plant), especially common in alkaline habitats, and it also tolerates brackish water, 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. A study demonstrated that "Phragmites australis" has similar greenhouse gas emissions to native "Spartina alterniflora". However, other studies have demonstrated that it is associated with larger methane emissions and greater carbon dioxide uptake than native New England salt marsh vegetation that occurs at higher marsh  elevations. 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. Invasive status. In North America, the status of "Phragmites australis" is a source of confusion and debate. It is commonly considered a non-native and often invasive species, introduced from Europe in the 1800s. However, there is evidence of the existence of "Phragmites" as a native plant in North America long before European colonization  of the continent. The North American native subspecies, "P. a." subsp. "americanus" (sometimes considered a separate species, "Phragmites americanus"), is markedly less vigorous than European forms. The expansion of "Phragmites" in North America is due to the more vigorous, but similar-looking European subsp. "australis". "Phragmites australis" subsp. "australis" outcompetes native vegetation and lowers the local plant biodiversity. It forms dense thickets of vegetation that are unsuitable habitat for native fauna. It displaces native plants species such as wild rice, cattails, and native orchids. "Phragmites" has a high above ground biomass that blocks light to other plants allowing areas to  turn into "Phragmites" monoculture very quickly. Decomposing "Phragmites" increases the rate of marsh accretion more rapidly than would occur with native marsh vegetation. "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. "Phragmites" is so difficult to control that one of the most effective methods of eradicating the plant is to burn it over 2-3 seasons. The roots grow so deep  and strong that one burn is not enough. Ongoing research suggests that goats could be effectively used to control the species. Natural enemies. Since 2017, over 80% of the beds of "Phragmites" in the Pass a Loutre Wildlife Management Area have been damaged by the invasive roseau cane scale ("Nipponaclerda biwakoensis"), threatening wildlife habitat throughout the affected regions of the area. While typically considered a noxious weed, in Louisiana the reed beds are considered critical to the stability of the shorelines of wetland areas and waterways of the Mississippi Delta, and the die-off of reed beds is believed to  accelerate coastal erosion. Uses. Stems can be made into eco-friendly drinking straws. Many parts of the plant can be eaten. The young shoots can be consumed raw or cooked. The hardened sap from damaged stems can be eaten fresh or toasted. The stems can be dried, ground, sifted, hydrated, and toasted like marshmallows. The seeds can be crushed, mixed with berries and water, and cooked to make a gruel. The roots can be prepared similar to those of cattails.