Wetland Ferns
What are they?
Ferns are primitive plants that evolved before the flowering plants and reproduce sexually by means of spores rather than seeds. This page covers the species that you are most likely to come across in open, wetland habitats, rather than shady places and most of them are clump-forming species, with just one forming spreading stands of vegetation.
Where are they found?
This page specifically covers ferns of open wetland habitats such as fens, wet meadows and open reedbeds. These species may also occasionally be found along riverbanks as well as in roadside ditches, while some persist for some time in wet woodland after their fen habitats have been colonised by scrubby trees such as alder or sallow. If you don't see your species here, try the species of woodland habitats.
Identification
The buckler ferns can be tricky to tell apart and it is necessary to note details of the smallest segments of the leaves, the spore cases and the outline and shape of the overall leaf. In the buckler ferns, the spores are covered by a round or kidney-shaped structure called an indusium and these lie in a double row along the underside of the leaflets. For ease of describing the various parts, a couple of technical terms are used; the side arms that form the first division of a leaf are called pinnae (singular, pinna), while the secondary divisions of the pinnae are called pinnules, which make up the smallest parts of each leaf.
Narrow Buckler Fern Dryopteris carthusiana
Native. Locally distributed in wet woodland throughout the region, being missing from many areas, but often very common where it occurs, especially in Broadland and East Suffolk. Spore-bearing fronds may be found from late May to August. Overall, the leaf has a relatively narrow outline with the lowest pairs of pinnae being the longest and the leaf having a noticeably long stalk. Pinnules end in sharply pointed teeth with incurved tips. The scales at the base of the leaf are pale, without dark centres.
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Broad Buckler Fern Dryopteris dilatata
Native. Common throughout most of the region in a range of wetlands, though more or less absent from Fenland and from the heavier, clay soils in south Norfolk and central Suffolk. Spore-bearing fronds may be found from late May to August. Overall, the leaf has a broad outline with the longest pinnae half way down the leaf and becoming shorter towards the base. Pinnules end in sharply pointed teeth with incurved tips. The scales at the base of the leaf are pale with an obvious, dark centre.
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Crested Buckler Fern Dryopteris cristata
Native. A rare plant which is classified as Critically Endangered. Found in a few, acidic bogs in Norfolk's Broadland and at two isolated locations on the north coast. Now lost from Suffolk, where it appears to have been last reported around 1975. Spore-bearing fronds may be found from late May to August. A distinctive plant, with open clusters of leaves that are not as tightly clumped as those of other buckler ferns - the outer leaves spreading outward, the inner more upright. The pinnae and pinnules are relatively broad but, on the inner, fertile (spore-bearing) leaves, they can appear narrow as the pinnae twist (sometimes to 90 degrees) on the main stem to give a ladder-like effect.
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European Royal Fern Osmunda regalis
Native in the Norfolk Broads in acidic wetlands but also thinly scattered elsewhere as an escape or relic of cultivation. Spore-bearing fronds present during summer. Ultimately a large and imposing fern, with leaves to three metres in length on the oldest plants. The smooth-edged pinnules without pointed tips, as well as the torch-like, upright spikes of fertile 'leaves' make this an easily identified species.
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Marsh Fern Thelypteris palustris
Native. Frequent to common in parts of Broadland but rare elsewhere in peaty wetlands. Spore-bearing fronds may be found from late May to August. This species differs from all our other wetland ferns in that it has creeping rhizomes that do not form discrete clumps or tussocks of leaves but form spreading mats. A relatively low species, with leaves to around 80cm in length. The spores differ from those of the buckler ferns in that they appear in lines around the outer edges of the pinnules, not in clusters at the centre.
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Common Pillwort Pilularia globulifera
Native. Once more common in wet, muddy ground, but rapidly declined and perhaps recently lost from our region. A bizarre fern, appearing like spreading mats of short grass, but the upright leaves are fleshy and - most distinctively - are curled at first and gradually unfurl. Spores are produced in ball-like structures, about 3mm across, borne at ground level along the creeping stems.
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