Juncus usitatus Seeds | Common Rush
LATIN NAME: Juncus usitatus
COMMON NAME: Common Rush
Plant Profile
Common rush is an Australian wetland plant that has become a workhorse of water treatment and revegetation, and it is a good garden plant in its own right. It grows as a dense, tufted clump of fine, cylindrical, bright green stems, forty centimetres to a metre tall, with a short rhizome that keeps the clump tight rather than spreading it across the mud.
The inflorescence is loose and open, with many small brown flower heads carried on slender branches, and it appears from spring into summer. The stems are soft enough to bend in wind and strong enough to stand through flood, which is exactly what a plant of creek margins and swampy flats needs. It is native to eastern and southern Australia, where it grows along watercourses, in swamps and in damp depressions that dry out in summer.
Science & Biotechnology
The species is one of the most widely used plants in constructed wetlands in Australia, and it has been studied for its capacity to take up nitrogen and phosphorus from wastewater and for its tolerance of fluctuating water levels. Its dense root mass and tight clumps slow water flow, trap sediment and support biofilm, which is the mechanism behind most of the treatment effect. It is also a useful indicator of wetland condition, since it declines when a site is drained or salinised.
Like many wetland plants it holds a persistent seed bank in the mud, and germination is triggered by exposure to light and by the drawdown of water, which allows it to recolonise a dried bed quickly. The genus is separated from the sedges by round stems and six-tepaled flowers, and from the grasses by the lack of a ligule and the arrangement of the flower heads. It is not the same plant as the European Juncus effusus, though the two look similar at a glance.
Uses & Benefits
Common rush is planted in reed beds, stormwater treatment systems, farm dams and wetland margins, where its job is to slow water, trap sediment and take up nutrients. In the garden it is a good plant for the edge of a pond or a boggy corner, and its fine, upright texture contrasts well with broad-leaved marginals. It is also useful for stabilising a bank that is periodically inundated, since the root mass holds soil against flow.
The stems have been used for weaving and for coarse matting, and the pith was used as a wick in the same way as other rushes. It is not the source of the Chinese medicine Deng Xin Cao, which comes from Juncus effusus, and it should not be substituted for it. Its main contemporary role is ecological rather than artisanal, and it is one of the cheapest and most effective plants for a wet corner that needs holding together.
Growing from Seed
Seed is tiny and needs light and constant moisture. Surface-sow onto wet seed-raising mix, press in without covering, and stand the tray in water at about twenty degrees. Germination is usually within three to four weeks, and it can be very heavy.
Prick out the seedlings into small pots of wet loam and grow them with the base standing in water. Plant out at the water’s edge or in wet ground in full sun, spacing them thirty to forty centimetres apart. Cut back hard in early spring to remove the old stems and make room for the new flush, and divide the clumps every three or four years when the centre begins to die out.
Our Take
A tidy, tough rush for wet ground and treatment beds, and one of the most useful wetland plants in Australia.
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