Marsh Fern

ESSEX BOTANY AND MYCOLOGY GROUPS

Marsh Fern:

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Thelypteris palustris L. MarshFern

(Thelypteris thelypteroides) (Lastrea thelypteris) Marsh Shield Fern

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Light 6. Wetness 8. pH 7. Fertility 5. Height <80cm unless fertile (<1.5m). Native & Introduced in Essex

Native. A very attractive and rather soft, delicate deciduous native fern with long creeping buried rhizomes that send up solitary bipinnate fronds at intervals along their length. The fronds die back completely in the autumn and do not reappear until late spring. Found in marshes, fens, alder-carr and valley flushes, with a scattered distribution throughout England and Wales plus a few outliers in Scotland. Rapidly declining through drainage. In the Flora of Essex 1974 the records were hopelessly confused with those of the closely related Lemon-scented fern. In Essex there are/were only 5 probably native colonies. One in the Woodham Walter Common Bog, saved from certain extinction by Geoffrey Pyman (but now lost again and doubtfully recoverable, the site being overgrown by Bracken); one in Holden's Wood, at Warley (though probably now destroyed), two in adjacent valley bogs at Gurnon Bushes (Coopersale Common), and one, only recently rediscovered and now tragically lost on Danbury Common. In addition it was introduced to Warley Place by the pond (now gone?), reputedly by Miss Ellen Willmott. In addition, under threat of extinction by the M11 motorway route, samples from the Gurnon Bushes sites were introduced widely in Epping Forest, and to the Pheasanthouse Wood Main Bog. The latter did not survive, as with most of the Epping Forest transplants. Although providing an interesting experiment demonstrating the pitfalls of introducing a plant to other sites, the whole exercise turned out to be needless, as the M11 route eventually missed the two bogs concerned (and clobbered an Equisetum sylvaticum bog instead). The record for Curtismill Green (FLORA 1974) was in error (teste RMP) for Lemon-scented Fern, and the record for Blakes Wood is a mystery, and almost certainly another species error (GAP).

In view of its rarity and national decline in recent decades considerable effort should be made to promote the populations at the Gurnon Bushes N.R. and attempt to recover the plant at Woodham Walter Common N.R., as well as maintaining the remaining introduced colonies in Epping Forest. It would appear that drying out of otherwise suitable bogs in summer droughts is likely to be the main cause of failure, but competition and light intensity are also clearly important. Geoffrey Pyman has shown how it is possible to bring populations back from the brink by clearing scrub and letting in sufficient light. If the EWT eventually acquires Holdens Wood there are several ideal bogs for marsh fern reintroduction. The plant is now so rare nationally that it would seem immaterial which sites are probably native and which are not. We need to maintain a good stock of the plant in as many suitable sites as we can. Frond counts can be used on an annual basis to monitor population success. The record from Wellmead, one of Miss Wilmott's other gardens in her Warley Gardens complex, in the pond on the western edge of a small block of woodland, 587,906 Brian L Coombes c.1982 is likely to be a misidentification for the large superficially similar Ostrich Fern colony that occurs there (comment Tim Pyner).

POST 1930 RECORDS:

TQ(51)49	420,990	18	Great Monk Wood, in the Viola palustris bog in two places, possibly introduced recently (by Les Chapman?), two short segments of rhizome bearing healthy fronds were found among the Viola in 1985 which have since become well established (1988). In 1988 a further patch with 8 fronds was found in a bare boggy area under sallow a few feet further downstream. This patch increased to 400-500 fronds by 5 June 1994. KJA. (N.B. these plants may have originated from the transplants pre-M11, see below).
		18	Great Monk Wood, still present in this bog, about 14 plants at the lower end and 50-60 at the upper end. October 2010.K.J.A.
	4326,9900	18	Copley Plain antitank ditch, a healthy colony has become well established about half way along this deep ditch. Most of the year it is inconspicuous and enveloped in willowherb etc. 9 OCT 1988. KJA; Still there 1993. Amanda Samuels. This colony was established from material in the Gurnon Bushes Bogs in 1973 when they were under threat from the M11 motorway. By 2004 the ditch had become scrubbed over. Clearance by the Epping Forest Conservation volunteers in 2004/2005 resulted in spectacular recovery. KJA. Still doing well in September 2010. KJA.
	4351,9945	18	Further colony in ditch south west of Oak Hill bog. July 1976. KJA. No sign in 2010, site scrubbed over and dried out. KJA.

TL(52)40	431,000		Lodge Road Bog North, a colony was found in the sphagnum carpet at the upper end of this bog in 1973. During the late 1970s the bog dried out somewhat and bracken invaded the top end after the 1976 drought. Since then it has become wet and boggy again, but the marsh fern had gone by 15 September 1978. KJA. This was presumably one of the sites of introduction of material from Gurnon Bushes, although the grid ref given in the NCC report suggest Lodge Road bog south.
	4439,0012		Epping Thicks, a colony was reported from a bog in this area by Brian Coombes c. 1982?. This could be the colony labelled "nr Ambresbury Banks" in the NCC report of transfer sites. Refound in 1995 by Amanda Samuels. Large colony in a bog along the north flowing tributary of the `Thames Valley' just west of Theydon Golf Course, three or four metres long with something like 40 fronds. She could not refind the colony in 2002.
	480,026 & 481,026		Gurnon Bushes N.R., large colonies occur in stream bogs at this site. The stream draining Gurnon bushes rises in four separate springs giving rise to two streams with permanent water, and two that are usually dried up in summer. Unfortunately ever since the M11 cutting was made nearby the level of the two permanent springs has fluctuated up and down the valley in response to the vagaries of the now reduced catchment. In the south eastern-most bog the marsh fern coexists with other vegetation in a wide flush just below the source spring. This site needs monitoring as it has recently been opened up (2006). The adjacent valley has two separate colonies that look rather more healthy, one growing beneath hornbeams along an otherwise barren segment of the stream. All three colonies doling well June 2007. KJA et Pteridol.Soc.

TL(51)59	592,909	18	Holdens Wood, Warley. Brian L Coombes discovered about 5 fronds in a bog on the eastern side of Holdens Wood in 1980. These were subsequently destroyed by motorbike scrambling. When I visited the site it was difficult to be sure whether this colony arose from a recent reintroduction. However Marsh fern was originally found somewhere in Warley Woods, most probably Holdens Wood, as it is recorded in the Essex Naturalist ( 17 p.48 1912) that Miss Ellen A Willmott of nearby Warley Place moved some plants to her pond at Warley Place, where Stanley Jermyn reported finding it `in small quantity' (late 1960s?). There does not appear to be any sign of it now. Brian Coombs reported finding a colony at Well Mead, but Tim Pyner has shown that this is Ostrich Fern.

TL(52)70	789,069	18	Woodham Walter Common sphagnum bog, growing with the rare liverwort Trichocolea tomentella 1952. Francis Rose, Ronald M Payne, Geoffrey A Pyman.This bog became very overgrown, but by clearing out the birch scrub that had invaded it in 1979 the marsh fern was given a new lease of life and the frond count increased from around 90 to 280 by 1983. Count for 1980, 80 fronds; 1989 only 20 fronds GAP. As a result of neglect resulting in Bracken invasion, and the summer droughts this colony was down to 4 fronds in 2005 and none in 2006, 2007 or 2008. KJA.
	7778,0437	18	Danbury Common, boggy thicket, small colony of c.6 fronds on east bank of the east branch of the stream that passes under Ludgores Lane just before its confluence with the main stream. Found by Howard Price in 1995 and last seen in 2000. Almost certainly the same site as mentioned by G S Gibson as being found by Arthur Willis (Gibson's Flora of Essex 1862).
		18	Blakes Wood, Stanley T Jermyn (FLORA 1974). This record is a mystery.
		18	Pheasanthouse Wood main bog introduced to this bog from Coopersale in 1973. Subsequently died out.

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PRE 1930 RECORDS:

	Boggy wood at Danbury, Arthur Willis. (GIBSON' FLORA 1862)
	Wood nr. Little Baddow Common, Edward Forster, Thomas Moore. (GIBSON' FLORA 1862)
	Woodham Walter Common, Alfred Greenwood. (GIBSON' FLORA 1862)
	Woody bog in field nr. Epping. Edward Forster. (GIBSON' FLORA 1862)
	Epping. Thomas Moore. (GIBSON' FLORA 1862)