Phragmites australis Seeds | Common Reed
LATIN NAME: Phragmites australis
COMMON NAME: Common Reed
Plant Profile
Common reed is a grass that behaves like a tree in the landscape. The culms rise two to four metres, hollow between the nodes, stiff enough to stand through winter, and they carry long, flat, grey-green blades that arch away from the stem and rustle in any wind. Below ground the plant is a thick network of creeping rhizomes, pale and jointed, running through the mud and sending up new shoots at intervals, and it is the rhizome rather than the seed that builds a reed bed. The root tissue is full of air spaces, which is how the plant breathes in waterlogged ground where the soil has no oxygen at all.
The flower head is a dense, feathery panicle, twenty to forty centimetres long, purplish brown when young and silvery when the seed ripens, and it persists through winter, catching the low light. The species is genuinely cosmopolitan, found on every continent except Antarctica, and it grows in fens, marshes, lake margins, estuaries, roadside ditches and any wet ground that is not too acid. It is a pioneer and a coloniser, and it builds the deep organic soils of the reed beds that support bitterns, bearded tits and a long list of invertebrates. In Europe the plant has been managed for thatch for a thousand years, and the cutting itself maintains the habitat.
Science & Biotechnology
Phragmites has become an important case in invasion biology because the species is native to North America but has also been introduced there. The native lineage, now treated as a subspecies, has been largely displaced in many wetlands by a Eurasian lineage introduced in the nineteenth century, and the two are almost indistinguishable in the field. Molecular markers separate them, and the spread of the introduced lineage has been mapped across the continent. The success of the invader is tied to disturbance, nutrient enrichment and altered hydrology: it responds to added nitrogen with vigorous growth, and it tolerates both draining and permanent flooding better than most competitors.
Studies of clonal growth have produced some striking numbers. Because the rhizome network is continuous and long-lived, a single genet can cover hectares, and estimates of clonal age in European populations run to many centuries, with some claims of a thousand years or more. Work on the plant’s aeration tissue has described the way oxygen moves down through the culm to the roots and how much of it leaks into the surrounding sediment, which affects the chemistry of the mud and the availability of nutrients. Hybridisation with the native subspecies has also been documented, and the hybrids are fertile, which complicates both conservation and management. Research on reed die-back in Europe has linked sudden collapse of stands to water level changes, sulphide toxicity and pest outbreaks.
Uses & Benefits
The practical uses are old and various. Reed is the classic thatching material of western Europe, cut in winter, graded by length and laid in bundles; a good reed bed is a renewable crop that needs harvesting to stay healthy. The stems are woven into mats, screens and baskets, used for fencing and plant supports, and pulped for paper. In constructed wetlands the plant is planted deliberately to take up nitrogen and phosphorus from wastewater and to oxygenate the root zone, and reed beds are a standard low-energy treatment for small settlements. The rhizome, Lu Gen, is a Chinese medicine for fever with thirst and irritability, and it is one of the few marsh plants in the materia medica.
In the garden the plant is a serious proposition and should be treated as one. It is magnificent beside a large pond or in a bog garden, where its height and winter silhouette are unmatched, but it must be contained in a rigid liner or a submerged barrel, because the rhizome will otherwise cross a garden in a few seasons and invade lawns, borders and drainage. It is not suitable for a small garden or for a natural pond where the aim is diversity, since it will dominate. Where it is wanted, plant it in a basket sunk in deep water and cut the stems in late winter.
Growing from Seed
Seed is viable but slow, and it germinates on wet mud rather than in water. Fill a tray with a muddy mix, saturate it until there is a film of water on the surface, scatter the seed thinly and press it in without covering. Keep the tray flooded to a depth of a centimetre and in full light at twenty to twenty-five degrees. Germination begins in two to four weeks. The seedlings are small and must be moved into individual pots of wet mud as soon as they can be handled, and they should stand in water from that point on.
Division is far quicker and is how the plant is usually propagated. Lift a section of rhizome in early spring, cut it into pieces with two or three healthy buds, and plant them in pots of wet loam standing in a tray of water. They root within a month. Plant out into shallow water or wet soil in full sun, in a lined container if the spread is to be controlled. Cut the stems to within ten centimetres of the water in late winter to keep the bed open and the growth vigorous.
Our Take
Common reed is a plant of enormous ecological and practical value and a thug in the wrong place. Grow it with a liner, in a big wet garden, and harvest it every winter.
Related Reading
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