Common reed (Phragmites australis) is a perennial flowering grass that is considered highly invasive. Common reed has thick roots and rhizomes that spread underground. Each plant produces thousands of seeds. The rapid growth of this species upsets the natural ecological balance by overwhelming native species, destroying habitats, threatening wildlife and increasing the potential for fires.
I. Appearance and Characteristics
Phragmites australis, known as the common reed, is a species of flowering plant in the grass family Poaceae.
Phragmites australis commonly forms extensive stands (known as reed beds), which may be as much as 1 square kilometer (0.39 square miles) or more in extent. Where conditions are suitable it can also spread at 5 meters (16 feet) 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 m (3 ft 3 in) or so deep, or even as a floating mat. The erect stems grow to 2–4 m (6+1⁄2–13 ft) tall, with the tallest plants growing in areas with hot summers and fertile growing conditions.
The leaves are 18–60 centimeters (7–23+1⁄2 in) long and 1–6 cm (1⁄2–2+1⁄4 in) broad. The flowers are produced in late summer in a dense, dark purple panicle, about 15–40 cm (6–15+1⁄2 in) 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 P. 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 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, P. 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 P. 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.
II. How to Grow and Care
Common reed thrives in wet environments and tolerates a broad range of soil types, highlighting its adaptability. Special care points include managing its invasive growth habit by containment or regular pruning, and ensuring consistent moisture levels without waterlogging. Generally, common reed has a low-maintenance care regime, suitable for novice gardeners.
Sunlight
Common reed flourishes best under full sun conditions, which involve direct exposure to sunlight for at least 6 hours per day. This high light intensity is crucial for common reed’s optimal growth, promoting vigorous development and robust health. In terms of light tolerance, common reed can adapt to partial sun scenarios, where sunlight is mixed with some shade during the day. Though somewhat resilient to reduced light, common reed’s growth rate and overall vitality may decline if deprived of their ideal lighting.
They have evolved to utilize ample light to their advantage, with their leaves optimizing to capture sunlight efficiently. Predominantly an outdoor dweller, common reed thrives in open areas that receive unfiltered sunlight, ensuring its position as a competitive species in natural habitats.
Watering
Common reed is a plant that thrives in wetland environments, indicative of its high water needs. It displays a strong preference for humidity and can tolerate occasional flooding. Its watering routine involves twice a week to mimic its natural habitat’s moisture levels. Being commonly found in outdoor settings, common reed benefits from rainwater, which supplements its regular watering schedule.
Propagation
The ideal seasons to propagate common reed are spring and autumn, with division being the preferred method. Propagation is generally easy, and successful growth is indicated by new shoots and root development. Ensure proper moisture and sunlight conditions for optimal results.
Transplanting
For successful transplantation of common reed, the perfect time is during early to mid-spring, as warmer temperatures stimulate growth. Select a location with ample sunlight and moist soil conditions. Remember, patience is key while transplanting delicate common reed plants!
III. Uses and Benefits
The entire plant is edible raw or cooked. The young stems can be boiled, or later on be used to make flour. The underground stems can be used but are tough, as can the seeds but they are hard to find.
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.
Common reed is the primary source of thatch for traditional thatch housing in Europe and beyond. The plant is extensively used in phytodepuration, or natural water treatment systems, since the root hairs are excellent at filtering out impurities in waste water. It also shows excellent potential as a source of biomass.
