Rushes
What are they?
Though a number of plant groups have the word 'rush' as part of their name, the true rushes are the species in the genus Juncus, which represent the greater part of the family Juncaceae, along with the rather dissimilar wood-rushes in the genus Luzula.
Where are they found?
Rushes are typically found in wetland habitats. Few species grow in standing water, unless land is only seasonally flooded, but most occur on open, muddy ground close to water, or in wet grasslands. One or two smaller species can occur as weeds of cultivation, especially on peaty soils and in peat-based composts in gardens, allotments and nurseries.
Identification
Although there is an overall similarity between the rushes, a combination of size, structure and flower or fruit details should separate species reasonably easily. Soil type can sometimes be useful, too, especially whether the soil is acidic or alkaline. Note whether leaves are present or absent and, if leaves are absent, whether the plants are tightly clump-forming, or spreading colonially, with individual stems arising well-spaced from the creeping root system. The presence or absence of rigid cross girders within the stem (which can be felt as small bumps simply by squeezing the stem and running thumb and forefinger along it) and the presence or absence of white pith inside the stem can be important. In some species, the size and shape of the fruits can be required for identification.
Soft Rush Juncus effusus
A native perennial, common to abundant in many kinds of damp, grassy places throughout the region and often forming large stands in wet grazing marsh and valley bottoms. Also commonly occurs as a weed of cultivation, especially in the horticultural industry. Flowers June to August. Plants 30-180cm in height, densely tussock-forming. Stems leafless, bright green with very smooth, shiny surfaces and the veins not raised into ridges. Inside, the stem has continuous, spongy, white pith and no cross girders, so stem when squeezed feels spongy and without internal ridges. Flower spike at the top of the stem, but topped by a long, stem-like bract with a soft tip. Flowerhead typically open, with broadly radiating branches, but they may also been densely compacted in variety subglomeratus.
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Compact Rush Juncus conglomeratus
A native perennial, widespread in wet places but strangely absent from much of the Fens and must frequent in North-east Norfolk and North-east Essex. Flowers May to July. Plants 40-100cm in height, densely tussock-forming. Stems leafless, bright green with clearly ridged surfaces that give the stem a less shiny look. Inside, the stem has continuous, spongy, white pith and no cross girders, so stem when squeezed feels spongy and without internal ridges. Flower spike at the top of the stem, but topped by a long, stem-like bract with a soft tip. Flowerhead densely compacted.
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Hard Rush Juncus inflexus
A native perennial, widespread throughout the region in damp places. Flowers June to August. Plants 30-120cm in height, densely tussock-forming. Stems leafless, tough, dull bluish-green with clearly ridged surfaces that give the stem a matt look. Inside, the stem has rather course white pith with many gaps, so stem when squeezed feels tough and wiry. Flower spike at the top of the stem, but topped by a long, stem-like bract with a soft tip. Flower spike very open with many, flexuous branches.
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Juncus x diffusus
The hybrid between Soft and Hard Rushes. Rarely recorded and may be overlooked amongst the parents, but certainly far from common. Flowers June to August. Intermediate between the parents, with stems green and lightly ridged. Flower spikes open but with stouter clusters of flowers than those of Soft Rush. Fruits can be poorly formed.
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Sea Rush Juncus maritimus
A native perennial, frequent around the coast in middle and upper saltmarshes and damp areas in dunes. Flowers July to August. Plants 30-120cm in height, densely to losely tussock-forming. Stems leafless, tough and smooth, not ridged. Flower spike at the top of the stem, but topped by a long, stem-like bract with a firm, spiny tip. Flowerhead typically open, but rather stiff and upright.
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Sharp Rush Juncus acutus
Native. Very local in the British Isles and largely a Mediterranean species. In East Anglia, small populations occur at the interface between sand dunes and saltmarsh in North-west Norfolk. Flowers June. Plants 30-150cm in height, stout and densely tussock-forming. Stems leafless, tough and smooth, but becoming lightly ridged with age. Flower spike at the top of the stem, but topped by a long, stem-like bract with a very firm, spiny tip that can be very painful if approached the wrong way! Flowers densely packed into stiff heads.
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Blunt-flowered Rush Juncus subnodulosus
Native. Widespread in peaty, calcareous wetlands and often forming extensive stands in mown fen meadows. Flowers July to September. Plants 40-130cm in height, spreading loosely from creeping root systems. Stems smooth and shiny with 1-2, tubular, rounded leaves, 20-120cm long. Inside, the leaves are largely hollow and with well-defined cross girders so when squeezed, they feel soft and with regular bumps, like the rungs of a ladder. Flower spike at the top of the stem, starting dense but becoming very open and intricately branched. Flower bracts pale brown. Seed capsule only just exceeds the length of the tepals and is pale brown.
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Sharp-flowered Rush Juncus acutiflorus
Native. Widespread but in peaty, acidic wetlands so typically not found on calcareous soils and absent from much of the boulder clay regions. Flowers July to September. Plants 30-160cm in height, spreading loosely from creeping root systems. Stems smooth and shiny with 2-4, tubular, rounded leaves, 5-50cm long. Inside, the leaves are largely hollow and with well-defined cross girders so when squeezed, they feel soft and with regular bumps, like the rungs of a ladder. Flower spike at the top of the stem, starting dense but becoming very open and intricately branched. Seed capsule exceeds the length of the tepals and is chestnut-brown, tapered towards a long-pointed tip.
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Jointed Rush Juncus articulatus
Native. Widespread in a wide range of neutral and acid soils, including in coastal areas with brackish water. Flowers June to September. Plants 5-80cm in height, with stems loosely tufted or spreading from a creeping root system. Stems erect to decumbent, smooth and shiny with 3-6, tubular, rounded or flattened leaves, 3-30cm long. Inside, the leaves are largely hollow and with well-defined cross girders so when squeezed, they feel soft and with regular bumps, like the rungs of a ladder. Flower spike at the top of the stem, few-branched but openly spreading. Seed capsule exceeds the length of the tepals and is chestnut-brown, rounded towards the top with a short, pointed tip.
Jointed Rush can be difficult to tell from Sharp-flowered Rush (and the two do hybridise!) so some plants may be very difficult to tell apart. Typically, Jointed Rush is shorter, often with prostrate stems. The flower spike is more elongate with fewer branches and the seeds are more bluntly rounded towards the top, with a short point.
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Heath Rush Juncus squarrosus
Native. Uncommon in wet ground on heathland and on acid, peaty soils. Most populations grow on the Norfolk Greensand, the Mid-Norfolk Heaths and in the Dunwich-Southwold area, but a few plants grow scattered elsewhere. Flowers June to July. Plants 15-50cm in height, densely tufted or forming small mats of leaf rosettes. Stems smooth with 0-1 leaves that are rounded beneath and deeply channelled above, 7-20cm long. Flower spike at the top of the stem, the flower tightly packed together. Seed capsule about as long as the tepals, rounded, with a short-pointed tip. The leaves and stems are very tough and wiry, feeling almost as if made of plastic.
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Slender Rush Juncus tenuis
Introduced from North America. Uncommon but slowly increasing on damp paths in woodland and in urban areas. Flowers June to September. Plants 10-60cm in height, densely tufted and often forming discreet leaf rosettes. Stems smooth with 2-3 leaves. Leaves relatively long, up to the length of the stems, flattened and grass-like, often curved. Flower spike at the top of the stem, rather open with clusters of flowers at the ends of long, radiating stems. Seed capsule much shorter than the tepals, broadly rounded. In North America, this species is known as Path Rush, a very suitable name given its habitat preference and ability to withstand trampling.
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Saltmarsh Rush Juncus gerardii
Native. Common in saltmarshes around the coast, often forming a dense community between the mid and upper saltmarshes. Flowers June to July. Plants 5-50cm in height, loosely tufted or with a creeping rhizome and forming spreading colonies like a grassy sward. Stems smooth, becoming three-sided towards the top and with 4-7 leaves. Leaves 2-30cm long, flat or slightly rounded. Flower spike at the top of the stem, rather open and stiffly upright with a few branches. Anthers 1.0-2.2mm, 2-3 times as long as their filaments. Seed capsule about as long as the tepals, broadly rounded; seeds 0.5-0.7mm.
Note: the rare Round-fruited Rush Juncus compressus is extremely similar and can only safely be told by measurements of the anthers and seeds. Anthers 0.5-1.0mm, 1-2 times as long as their filaments. Seeds 0.3-0.5mm.
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Toad Rush Juncus bufonius
Native. An annual species, widespread and often very common in wet, muddy situations in a wide range of habitats, including urban areas. Flowers August to September. Plants 5-40cm in height, loosely tufted or sometimes solitary. Stems with 1-5 leaves and leaf-like bracts around the flower spike. Flower spike upright, branched with flowers often solitary along the branches. Seed capsule much shorter than the tepals, narrowly rounded. The annual nature allows this plant to appear quickly in seasonally wet areas and it can persist for a time on dry ground after puddles and small pools dry up. Rather grass-like in appearance, but easily told from grasses by the lack of stem nodes and the six tepals.
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Bulbous Rush Juncus bulbosus
Native. A perennial of wet ground in acid bogs and flushes. In East Anglia, generally scarce and most frequently found in wet, heathy habitats in Norfolk. Flowers June to September. Plants 1-20cm in height, arising from corm-like bases to the stems rather than from rhizomes. Stems either upright or procumbent, from a tight tussock. Leaves mostly basal and up to 10cm in length. Flowers openly spaced in small clusters along the stems, with some flowers often replaced by adventitious shoots. Seed capsule equal to or slightly longer than the tepals, roundly three-sided.
Note: plants with six rather than three stamens with oblong anthers shorter than their filaments and dark brown tepals and capsules have in the past been considered a different species, Juncus kochii, but plants with intermediate characters occur and at the most now, such plangts are considered a subspecies or variety of Bulbous Rush.
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