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In 2012 various botanical surveys of Lea Marshes were compared. To view this comparison table click this link. | ||
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| APPENDIX
THE FLORA OF WALTHAMSTOW MARSHES: FIRST SUPPLEMENT, JANUARY 1981 | ||
| The original plant list for this important alluvial site was published in the first edition of this book in September 1979. Further systematic surveys early in 1980 (plus two omissions in the original text) now add ten interesting new species and hybrids to the list. Therefore, 21 years of field observations now bring the total to over 350.
No site's native flora can be considered thoroughly documented until every single square metre of terrain be closely examined at least once a month throughout the year. The 1980 surveys revealed rather dramatically that certain ecologically important plants on the Marshes had been incorrectly identified, due to lack of critical dissection at exactly the right season, even though some of these had clearly been present and probably widespread on the site for well over a century. This is certainly true of the Carex and Equisetum species and hybrids. The Carex populations, in particular, being ancient, are complex and variable, and still require comprehensive monthly study between May and August. In addition, Aster, Arctium, and Symphytum have not yet been exhaustively analysed to assess introduced or spontaneous hybridity; the infra-specific repertoire of Bromus, Festuca, and Agrostis would doubtless still repay attention: and the Taraxacum species are quite unknown (they could well include water-meadow originals). Salix has been satisfactorily covered and the 1979 records are accurate. Ten new plant records for Walthamstow Marshes in 1980 1 Equisetum x litorale : found to be the commonest Horsetail in all three meadows, particularly towards their railway and reservoir boundaries, where the bank constructions, 120 to 140 years ago, would have brought the parents into contact for the first time. This invasive hybrid tends to give way to E. palustre in the more peaty, and much older, Caricetum swamps further away from the boundary fences. It is new to Essex (not in Jermyn, 1974), unknown in Middlesex (see Kent, 1975) and not recorded for a large area from North London right through Central England (Perring & Walters, 1968). The last work gives it in only 47 10-km squares in England, Scotland, and Wales (E. limosum x arvense). 2 Equisetum limosum : a relict railway dyke aquatic, presumably a co-dominant constituent of the open water railway ditches of the last century, but now breathing its very last, with E. arvense, E. x litorale, and E. palustre in a shallow, damp, stony, two-square-metre hollow in the Triangle only. 3 Carex acuta : locally abundant and very fine in the wetter, older, parts of all three meadows, but does not grow by the Coppermill Stream. Its tall, slender, dark green foliage in dense stands, forms distinct zones with the next. 4 Carex x subgracilis (C. acuta x acutiformis) : this, not 'slender C. acutiformis' is now known to be the principal pasture sedge on the body of the Marshes. Its identity has now been confirmed both at Leicester University and at the British Museum, Natural History, in London. Its semi-glaucous rhizomatous stands extend widely over waterlogged, damp, and even rather dry ground, including railway banks. The stands are either pure, or co-dominant with C. acuta, C. disticha, Glyceria maxima, and other native species. Being largely, or totally, sterile, this plant's widespread occurrence on four sides of three railways indicates considerable antiquity, since this distribution could only have been achieved vegetatively before the railways had been built, in the middle of the last century. It could have arisen from a single cross-pollination many centuries ago, when the main drainage channel was open water with both parent species fringing it together, and when there was also open mud available for the hybrid seed to germinate. True C. acutiformis nowadays only appears to fringe the Coppermill Stream (it also grows in abundance around most of the Walthamstow Reservoirs); its terrestrial survival elsewhere on the Marshes now requires careful investigation. The other parent, C. acuta, is much more a plant of primary fen pasture, and is rarely or never found to recolonise secondary marsh or lakeside. The hybrid is very drought resistant, even competing with Agrostis and Agropyron; its foliage in December strikingly combines the parents' totally different Winter appearances, to create a scenic effect probably unique in Europe, if not anywhere in the world. The leaves are, in that season, wide, fresh, glaucous bronzy green and upright below (features of C. acutiformis), narrowing abruptly in the middle to an upper half which is very narrow linear, elongated, dead, pale straw-brown, and spreading-pendulous (features of C. acuta which dies to the ground rapidly in late Autumn). However, the progressive die-back of pure C. acutiformis foliage reduces this visual distinctiveness somewhat by February. Confirmed C. x subgracilis is recorded from only three or four other British localities (Stace 1975). It is new to Essex and to the entire London area. 5 Elodea nuttallii : now plentiful in the River Lea and the Coppermill Stream. When did this replace E. canadensis? 6 Alisma plantago-aquatica : omitted in error from main list 1979. By Coppermill Stream, scarce and precarious. 7 Alisma lanceolatum : omitted in error from main list 1979. In and around Bomb Crater Pond (South Marsh), only. Long known here, and nowhere else in the Lea Valley (?). It disappeared from 1977 to 1979, due to dumping of rubbish, but one plant re-appeared in 1980 and grew large. 8 Heracleum mantegazzianum x sphondylium : deliberately sought and one fine plant found on the South Marsh where the parents have been known to grow together for some years. 9 Cardamine pratensis : two very welcome clumps of this beautiful water-meadow species were found to be surviving near one of the railways in the Triangle only. 10 Rumexsanguineusvarviridis:onlyrecordedwithuncertaintyin1979,butasmallcolonyoftwoorthree plants were positively identified on the North Marsh in October 1979. An unusual occurrence for this typically woodland Dock, but quite distinctive from R. conglomeratus here. No hybrids. Welcome re-discoveries or newly-found increases of range Achillea ptarmica : one clump only of this was known by the Coppermill Stream from 1961 to 1965 and then 'lost'. The same plant, now vigorous, was rediscovered in October 1979. Sagittaria sagittifolia : one plant detected for the first time in the Coppermill Stream in June 1980. It is normally invisible here, being continually decapitated by canoeists. The River Lea plants, by the boating club and under High Bridge, have probably survived similar onslaughts for many decades, and thrive still, probably never flowering. Lemna polyrhiza : fairly numerous in company with L. minor, gibba and trisulca, in Coppermill Stream, and River Lea. Extinct in Bomb Crater Pond, where first noted in this area. Rumex palustris : several large plants found by Coppermill Stream, and also on open mud in drainage channel on North Marsh. Ophioglossum vulgatum : a fine ancient meadow species considered extinct here by 1977, when just a few plants first found in 1975 were all dumped on with rubble. However, an intensive search in June 1980 revealed about 15 thinly scattered plants in thick grass on the North Marsh, near Coppermill Bridge. Also, several hundred small to moderate plants, some fruiting, showed fresh through recently-burnt Caricetum, all over the drier parts of the South Marsh. They must have been there for hundreds of years, yet only recorded at "Lea Bridge, 1845" (Kent and Lousley, 1951, p.331). They are normally quite concealed by predominant, tall, Carex disticha. Although this species is recorded in relatively numerous 10-km squares in Perring and Walters, 1962, it is a local and decreasing species whose survival in an urban area is of outstanding interest. Colutea arborescens : a new shrub has appeared on the North Marsh, far from the railway. Carex disticha : found to be plentiful, sometimes dominant, on important parts of both North and South Marshes. It was recorded in 1979, but its quantity much under-appreciated. Miscellaneous observations 1980 Rumex x lousleyi (R. cristatus x obtusifolius) : one of the only two colonies known in the world, and the only one in Essex (the other one in Middlesex), is now regularly cut to the ground by the LVRPA and did not flower in 1980. The infra-specific R. obtusifolius hybrid swarm is steadily declining. Phragmites communis : stands were relatively stunted in 1980 due to excessively dry Spring. Salix caprea x atrocinerea : is apparently dying (one tree only). Salix purpurea : in the Lea Valley is apparently now restricted to small Broxbourne and Coppermill colonies. It seems no longer able to reproduce itself sexually, nor to recolonise secondary habitats, and should therefore be considered an endangered species. Not seen in 1980 Veronica beccabunga, Eupatorium cannabinum, and Berula erecta may finally have succumbed to Glyceria invasion by the Coppermill Stream. This grass requires strict management. Lysimachia vulgaris has not been re-found by the railway bordering the North Marsh. Alopecurus geniculatus : is losing ground to Agropyron repens; symptomatic of habitat drying. Ten notable absences from Walthamstow Marshes never recorded there; still worth seeking? Ranunculus flammula, Zannichellia palustris, Groenlandia densa, Potamogeton trichoides, Lychnis flos-cuculi, Thalictrum flavum, Caltha palustris, Bromus commutatus, Polygonum minus, and although this last was seen once only in 1961, Carex pseudocyperus. References Jermyn, 1974 Flora of Essex (Essex Naturalists Trust) Kent, 1975 : The Historical Flora of Middlesex (The Ray Society, London) Kent & Lousley, 1951 : A Hand List of the Plants of the London Area (The London Naturalist) Perring & Walters, 1962 : Atlas of the British Flora (BSBI) Perring & Walters, 1968 : Critical Supplement to the Atlas of the British Flo (BSBI) Stace, 1975 : Hybridization and the Flora of the British Isles (Academic Press) Brian Wurzell. March 1981. Walthamstow Marshes: the 1970s Survey by Save the Marshes Campaign Reproduced by Mike Trier, 2007, with the kind permission of John Nash, Save the Marshes Campaign Copyright © Mike Trier, 2007 (online version produced in 2012 as copyleft, though the original content producers may still have some rights). Geological map © J. D. Nash & D. J. Gibbins, 1981 (1970/2007) | ||
| This version is copyleft. Whilst some of the original material may belong to John Nash and the style of the 2007 reprint is the copyright of Mike Trier, the style of this HTML version is copyright free. This version has been published with the permission of Mike Trier and attempts were made to contact John Nash to seek his permission. | ||