Lea Marshes   1970s Survey   In 2012 various botanical surveys of Lea Marshes were compared. To view this comparison table click this link.   Walthamstow Marshes: Habitats      GENERAL RESUMÉ OF HABITAT TYPES TREPRESENTED ON THE MARSHES   1 Open Water Of River Lea, and its Backwater (correctly called the Coppermill or Silk Stream). This contains varied aquatic life and animal life. There is still a very little open water in the small pond by Coppermill railway bridge (our only locality for the rare Lesser Reed Mace), but Reed Grasses are encroaching (as they are also in the Stream), and both would benefit from some clearance of marginal mud and vegetation. A small ancient pond in the Outer Marsh (Triangle area) is now a damp hollow by a relict ditch, but False Fox Sedge and Tubular Water Dropwort still persist there, and they grow nowhere else hereabouts. The bomb-crater pond in the south field used to be very interesting, but it is now largely spoiled by the unauthorised dumping of rubbish. It would be very desirable to restore this, and to dig one or two other ponds of this size in the Coppermill area, as very small aquatic habitats of this kind have much value and interest in many ways. The Ecology of the Walthamstow Waterweeds The zonation of the various plant communities found from open water through to dry land always offers rich scope for interesting ecological surveys and demonstrations. The following plant communities may be observed: Totally submerged species: Fennel Pondweed, Frog's Lettuce, Canadian Waterweed (Elodea), Water Milfoil, and Hornwort. Marginally submerged species Ivy-leaved Duckweed always occupies a very narrow subsurface zone, mixed only with algae. Floating Species Common and Fat Duckweeds are abundant on the water surface. I have recently re-discovered the Great Duckweed, mixed with these other two, on the surface of the River Lea itself, in small quantities. Plants which overlap all the above zones, and have developed a most interesting range of leaf variations to adapt to each zone, include: Water Starwort, Yellow Water Lily, Branched Bur-Reed, and Water Crowfoot. The contrasts of floating and terrestrial leaf forms of the Water Bistort are also very striking. The latter form is commoner. 2 True Waterside Marsh The Reed Mace species, Lesser Pond Sedge, the Reed Grasses Glyceria and Phalaris and sometimes Phragmites, are among the very first tall marsh plants to invade open water, and begin land reclamation from it. The more beautiful plants of this zone include Great Water Dock, Purple Loosetrife, Yellow Flag, Sweet Flag, and Orange Balsam./td> 3 Open Expanses of Semi-Marsh Grassland These are subject to flooding in very wet spells, but often dry in Summer, and capable of surviving prolonged drought. This habitat is reminiscent of the Fens or the Broads, with extensive wind-rippled stands of the grasses Glyceria, Phragmites and Phalaris, mixed with Sedges. Here we find characteristic marshland species, including Meadowsweet, Water Mint, Water Pepper, Bur-Marigold, Hairy Willowherb, Angelica, Skullcap, Wild Hop, Hedge Bindweed, and Gypsywort. Michaelmas Daisies have recently become thoroughly established in the company of these others, and are all now of natural spontaneous origin (not planted), exactly as they appear at Wicken Fen, Cambridgeshire, or the rolling meadows of the Mid-West of the USA. They are now so abundant that they make a most spectacular and beautiful display on the Marshes in September. Several species and hybrids are involved. 4 Rough Pasture This may approximately be divided into the following sub-categories: (a) Predominantly Couch Grass, succeeding the above semi-marsh community in progressively drier and more stabilised soil conditions. (b) Association of Couch Grass with Russian Comfrey, the two plants co-dominant, or associated with smaller quantities of stinging nettles, Thistles, Prickly Lettuce, False Oat, Hogweeds, and various Docks. Or any combination of these. This is a particularly rank mixture, and is characteristic of former grassland which was disturbed by man, and then left - probably previously a semi-marshland plant community of Category 3 type, as above. This demonstrates very clearly how sensitive long-established grassland is to any change, and how it can never be restored to its original condition once the ground has been broken. For the flora which colonised broken ground will always be different from that which was there before. This "4b" Category is typical of heavy (clay) soil disturbance. On the other hand, if the disturbed soil is lighter, or more loosely dumped, material left in mounds, it will give rise to a succession of common weed annuals, which will rapidly give way to perennials, and then culminate with Sallow scrub. This flora development can clearly be seen opposite the marina, where soil was dumped in the course of its recent construction. (c) Meadowland association of Couch Grass with Tufted Vetch, Meadow Vetchling, Tall Fescue, Creeping Thistle, Common Ragwort, and Meadow Buttercup. This community tends to be a less rank mixture, occurring on drier soil, and probably of more ancient disturbance than the last. This assumption is supported by a richer associated insect fauna, including Burnet Moths, and Meadow Brown and all the Skipper Butterflies. This more desirable habitat will not develop on newly disturbed soil straight away, and it takes many years for it to become relatively stable. 5 Dry Grassland This can approximately be divided into the following sub-categories: (a) The next stage in succession from the last category (4c), in drier turf, with the following species tending to replace the Couch Grass: Black Knapweed, Yarrow, White Clover, Cock's Foot Grass, Yellow Oat, Fine and other Bent Grasses, Rosebay Willowherb, Yellow Toadflax, Cat's-Ear, and various Hawkbits. (b) This habitat in mown condition, to become playing-fields, in which case the taller species will normally be eliminated altogether, but most of the smaller ones will usually survive in stunted, non-flowering, condition, together with those additional plants which are particularly characteristic of well trodden pathways. (c) This same habitat again but on artificial inclines, such as railway banks, or the banks of the Lea Bridge Road playing-field (Leyton Marsh), which has in the past been a rubbish tip. On these less controlled slopes, where mowing is not possible, any or all the above plants may be accompanied by larger plants, including Oxford Ragwort, Soapwort, Greek Dock, and Japanese Knotweed (which are all very familiar natives). It must be emphasised that the species given as being "typical" of these categories should not be assumed to grow exclusively in them. They will naturally tend to occur also, in smaller quantities, in those habitats most closely related to the ones under discussion. There are no absolute delineations in nature. 6 Hard, Trodden Pathways Although difficult to understand how plants can survive in such harsh growth conditions, there are nevertheless species which not only do so, but even specialise in them. Many of these have evolved crush-proof rosette leaf arrangements, like Plantains, Daisies, and the first-year growths of a wide range of biennial species, so that the feet of animals and man do them no harm whatsoever. In addition to this, such species, and other non-rosette forming plants, may produce strong but flexible stems, to ensure survival. These include Plantains, Knotgrass, Pineapplewood, Rye-Grass, Annual Meadow Grass, Dandelions etc. 7 Old Brickwork and Concrete River banks and railway bridges generally support a poor depauperate selection of species more characteristic of waste ground, like Oxford Ragwort and Rosebay Willowherb. A few Lichens and Mosses may be found locally in small numbers. 8 Railway Ballast A very distinctive and characteristic association of Sticky Groundsel, Common Horsetail, Field Bindweed, Yellow Toadflax, and particularly, Small Toadflax, the latter restricted entirely to this habitat, where it is common. 9 Newly Disturbed Ground The study of pioneer plants on bare soil has many interesting ecological implications. In this area, we normally have a combination of so-called weeds of parks and gardens, but at Walthamstow, these are usually mixed with examples of marsh plants, which in these conditions may enjoy a brief period of exceptional luxuriance. Such communities are necessarily very fugitive, for the stronger perennials of the area will soon encroach and take over, as the next stage in succession. Plants which may turn up only once or twice and not be able to persist are termed "casuals" in the species list given later. Many of these are alien introductions from gardens or with canary seed. Consequences of a Major Upheaval From the above account, it can straightaway be seen that the water, marsh and above all the particularly valuable grassland habitats would be totally destroyed, beyond all hope of restoration in their present forms in our lifetime. Habitat balances are very delicate situations, especially if they have evolved over a long period, as here. The sallow scrub we now have on Walthamstow Marshes is valuable for insect and bird life, but we have enough of it to serve its purpose, and it would not be desirable for it to increase further, at the expense of the grassland. Any sallow colonisation of either of the two outer marsh fields would similarly be undesirable. The Russian Comfrey colonies have limited ecological value and should not be encouraged to increase. Click to go to next section