Club-rushes, Cottongrasses and Allies
What are they?
The plants on this page are all members of the Sedge Family (Cyperaceae) but all differ from the sedges in the genus Carex in having perfect flowers, i.e. flowers that bear both male and female parts. Typically, the female stigmas mature first, with the stamens following later and there may sometimes be an overlap between the last stigmas and first stamens within a spikelet of flowers. In this group, the flowers are greatly reduced, rather like they are in the grasses. Each flower has a single bract at its base, accompanied by the stamens and stigma. The remains of a perianth (what would be the petals and sepals in many flowers) often exist as a series of small bristles at the base of the flower.
These plants are closely related to the spike-rushes and allies but mostly differ in having multiheaded spikes of flowers.
Where are they found?
The great majority of plants in this group are wetland species and can be found in wet habitats or, often, growing within the margins of standing water in fens and mires.
Identification
The various genera within this broad group of plants are different enough from each other to be easy to tell apart from the photographs. However, within the genera, careful attention to detail of the flower or fruit structures is sometimes required. This may require a microscope, so it may be necessary to take a small sample home for later dissection. Small portions of a flower cluster can be removed without the need to take large quantities.
Sea Club-rush Bolboschoenus maritimus
Native. Common around the coast and inland along brackish portions of coastal floodplains. Often forms large stands along borrow dykes behind coastal defence embankments. Flowers June to August. Plants 25-100cm in height, spreading by rhizomes to produce swards of vegetation. Leaves 10-35cm long, broad and grass-like. Flowerhead a cluster of 1-10 spikelets and accompanied by a long, leaf-like bract. The spikelets are typically densely clustered but may sometimes be on longer branchlets, producing a more open head.
Until quite recently, this could be considered a distinctive and easily-recognisable species. However, more recently, Inland Club-rush has been found within our region, so care needs to be taken with plants further from the coast or around fresher bodies of water. Sea Club-rush has a rounded fruit with 0-2 perianth bristles at its base. The nutlets inside are more or less plano-convex in cross-section; that is to say, flattened on one side and gently rounded on the other. Of the outer two layers, the outer will be seen to be thicker than the inner.
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Inland Club-rush Bolboschoenus laticarpus
Probably native and perhaps being distributed via migratory waterfowl that eat the fruits. Still little-known in the UK but proving to be frequent in Somerset and so far recorded in Cambridge and North Norfolk in our region. Generally found around freshwater ponds rather than brackish water. Flowers June to August. Typically differs from Sea Club-rush in the spikelets being more elongated (though this can be true of Sea Club-rush at times) and clustered on 3-6 longer stalks.
Inland Club-rush has an oval fruit with 1-6 perianth bristles at its base. The nutlets inside are more or less triangular in cross-section. Of the outer two layers, the inner will be seen to be thicker than the outer.
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Common Club-rush Schoenoplectus lacustris
Native. Quite common along the larger rivers in much of the area, typically growing from beneath the water surface rather than from the banks. Flowers June to July. Plants up to 3m in height, spreading by rhizomes to produce open stands of vegetation. Leaves relatively short (to 15cm) and usually better developed lower down, beneath the water surface. Flowerhead typically an open cluster of tight spikelets (or occasionally a solitary spikelet) on side branches of varying lengths. Flowers with three stigmas and flower bracts reddish-brown, smooth on the outside.
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Grey Club-rush Schoenoplectus tabernaemontani
Native. Widespread but far less common than Common Club-rush, though replacing it near the coast as the water becomes more brackish. Flowers June to July. Plants up to 1.5m in height and typically more blue-green in colour than the green of Common Club-rush. Flowers with two stigmas and flower bracts densely stipuled with rusty bumps.
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Wood Club-rush Scirpus sylvaticus
Native. A rare species in eastern England with a scattering of locations in eastern and South Suffolk, southward into Essex, in wet, silty pastures and woodland. Flowers June to July. Plants 30-120cm in height with a creeping rhizome and three-sided stems. Leaves 10-35cm long, flattened and with rough and thickened margins. Flower stigma opening out into a broad, many-branched head with many pale flowers in small clusters.
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Black Bog-rush Schoenus nigricans
Native. Scarce and thinly scattered on chalk-flushed, peaty soils, mostly in Norfolk and rare or absent elsewhere. Flowers May to June. Plants 15-80cm in height and forming compact tussocks of tough, thin and wiry stems and leaves, the leaves mostly basal. Flower carried in a tight cluster of spikelets with dark chocolate-brown or blackish bracts and a stem-like bract longer than the flower spike.
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Great Fen-sedge Cladium mariscus
(Saw Sedge) Native. In England, this species is very much an East Anglian speciality, with the majority of the population occurring in the Norfolk Broads where it sometimes forms extensive stands. Elsewhere, it is thinly scattered across the region in fen habitats. Flowers July to August. Plants to 2m in height with stout, rounded, finely-ridged stems. Leaves flattened and course with tough, sharply serrated margins. Flowers carried in a series of tight clusters along the stem with the uppermost cluster broadening out more, which is unique in our region.
The leaves are traditionally harvested in summer as flexible material to make the curved riges and fashioned shapes required for thatching.
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White Beak-sedge Rhynchospora alba
Native. A rare species of valley mires and bogs, lost from former sites in Suffolk and currently known from just five locations in Norfolk. Flowers July to August. Plants 10-40cm in height with slender stems. Leaves 10-15cm long, flattened. Flowers carried in small, terminal clusters with white tepals.
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Common Galingale Cyperus longus
Considered to be a rare native in southern and western Britain but introduced our region, as in much of the country. Occasional in wet places, most often where planted around village ponds. Flowers July to August. Plants 20-150cm in height with slender stems. Leaves up to 60cm long, flattened, strongly ridged and forming dense stands of arching foliage. Flowers carried in double rows in finger-like spikelets in a branched head.
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Pale Galingale Cyperus eragrostis
Introduced from the Americas as a garden ornamental and increasingly appearing as a garden throw-out in urban locations. Not tied to damp places and often a weed of rough corners, roadsides and streets. Flowers July to August. Plants 20-150cm in height with slender stems. Leaves up to 60cm long, flattened, strongly ridged and forming dense stands of arching foliage. Flowers carried in double rows in finger-like spikelets in a branched head. The spikelet clusters are typically pale yellowish- or whitish-green and in an umbel of rounded clusters, with 5-11, leaf-like bracts at the base of the head.
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Round-headed Club-rush Scirpoides holoschoenus
A rare native in South-west England, but also introduced from mainland Europe as a garden ornamental and recently recorded from Cambridge and Colchester. Flowers July to September. Plants 30-90cm in height, forming tussocky stands from creeping rhizomes. Leaves mostly basal and reduced to stem sheaths. Flower spikes distinctive and unlike any of our native species, with the spikelets arranged in globular clusters on radiating side branches.
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Common Cottongrass Eriophorum angustifolium
Native. Favours acid bogs and mires so rather local in East Anglia and mostly found in Norfolk and North-east Suffolk. Flowers May to June. Plants 15-60cm in height with slender, loosely scattered (not tufted), rounded stems. Leaves 2-60cm long and 3-5mm wide, flattened, channelled but with the channel ending well short of the leaf tip. Flowers carried in a cluster of club-like spikelets, emerging upright but soon pendulous. Flowerhead branchlets (peduncles) smooth.
Flowering heads of cottongrasses resemble those of some sedges, but the floral bristles extend to become a cottony mass of hairs with the onset of fruiting and these fluffy heads are persistent through autumn and early winter, giving the plants their name.
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Broad-leaved Cottongrass Eriophorum latifolium
Native. Favours acid bogs and mires that are flushed with chalky water. Rare and declining in our region; extint in Suffolk and found in perhaps less than five sites in Norfolk. Flowers June to July. Plants 20-70cm in height with loosely tufted, rounded stems. Leaves 2-60cm long and 3-8mm wide, flattened, channelled but with the channel ending short of the leaf tip. Flowers carried in a cluster of club-like spikelets, emerging upright but soon pendulous. Flowerhead branchlets (peduncles) with rough, forward-pointing hairs.
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Hare's-tail Cottongrass Eriophorum vaginatum
Native. A common plant on upland moorland but always rare in East Anglia and known only from two locations in Norfolk, one of which was discovered in 2019. Flowers May to June. Plants 30-60cm in height and forming leafy tussocks. Leaves up to 50cm long and 1-2mm wide, flattened. Flowers carried in a single terminal spike and forming a fluffy' hare's tail' when in fruit.
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