The Natural History of Askern Bog by Dr. H. H. Corbett

To the field naturalist in pursuit of his favourite study, those bits of country that have been least affected by man present the most favourable grounds. Ancient forests, such as the New Forest in Hampshire, or Sherwood Forest in Nottinghamshire, the open moors of the Pennine Range, the few patches of remaining fen in Cambridgeshire and Huntingdonshire, extensive peat bogs such as those of Thorne & Hatfield, or the rolling sand dunes of our coasts, all present Nature in a more natural state than she is to be seen when manufacture or agriculture claim entire sway.

It is to one of the little wild scraps of country that I would now draw your attention. As one approaches the village of Askern by road from Doncaster, one sees on either side of the highway two very different types of country. That on the left is undulating and dry, the land rising somewhat steeply from the roadside; indeed, the road just skirts the outcrop of the magnesium limestone. The right side, however, shows a very different aspect. Flat fields, intersected by broad ditches, and immediately at the edge of the village is a small extent of uncultivated bog, bounded on its further side by a broad winding pool. It is to the natural history of this little morass that I would now draw your attention.

As a naturalist, I an sorry to say that year by year its area gets more restricted, and the time is probably not far distant when Askern bog is a thing of the past, when agricultural crops will have taken the place of the plants now growing there, and one of the few remaining little bits of this rich and widespread fen-land flora and fauna of our neighbourhood will have gone never more to return. Let me take you, in imagination, through the small wicker gate close to the Bath House, and see what is to be seen of interest in the bog.

An exhaustive essay of the natural history of any locality must comprise a review of the objects to be found there the whole year through. This I will not attempt, but instead will suppose our visit to take place on a fine day in July, and during a protracted spell of dry weather. For I may warn intending investigators that during wet weather that many parts of the bog are somewhat deceptive and dangerous nature, and the unwary enthusiast is apt to be bogged too deeply for comfort. This first impression of the vegetation of the bog is that it is composed of rushes, sedges, and course grasses, with here and there a few willows. But we soon that there are many flowering plants to be seen. Perhaps the first to attract attention at this time of the year is the Meadow Sweet (Spirea ulmaria), which soon makes its presence known by its characteristic scent. Growing along with it and easily passed by from its general similarity to the Meadow Sweet, is a much rarer plant and one much more typically belonging to the marsh land. The tall, glabrous and leafy stems with a panicle of numerous cream-coloured flowers might, as I said, be easily passed by as those of the Meadow Sweet, but if the flowers of the two plants be examined more closely, they will be seen to be completely different. Those of the Meadow Sweet are to all intents and purposes small roses with cleft calyx and five petals surrounding the numerous stamens and pistils. On examining the other plant, we find instead of five petals there are no petals at all, but only a very numerous group of stamens and pistils surrounded by a calyx. This plant is indeed a very simple form of the buttercup group of plants. Our plant turns out to be the Thalictrum flavum, but this species apparently embraces several sub-species, and to which of these it should be referred requires a specialist. Any how we can see that it is a very beautiful plant, and furthermore it is a true marsh plant and one likely soon to be improved off the face of the earth so far as this locality goes.

While we were examining the Thalictrum we became aware of a curious bleating or humming noise in the air, now faint and hardly heard, then swelling out louder until it seems to fill the air all around us, then we see what is the cause of this noise, flying above us and ascending in spirals, after the manner of the skylark, is a small bird with rather long legs and a very long bill. Suddenly, he drops towards the earth with wings half-extended and tail spread fan-like, and as he drops the bleating sound is found to proceed from him. He is a cock snipe, and is singing his love song to his mate, who is sitting on her eggs or brooding her young in the marsh. This song does not proceed from his throat as those of most birds do, but is caused by the vibration of the feathers of his tail as he plunges downward through the air.

Innumerable little moths flu about among the grass and sedge, and when on the wing appear to have broad and ample wings, as they really have, but as soon as they alight on the grass stems the wings seem to disappear, and the inset appears to become part and parcel of the stem upon which it has settled. If one be caught and examined it will be seen that the fore wings are comparatively narrow and the hind wings very ample, but when the insect settles these broad wings are folded like a fan, and the narrow fore wings are rolled round them, so the fly assumes the aspect of a bit of grass stem.

While watching and catching the Crambus we have seen two plants, both of which are of interest, being peculiarly marshland species, and one of them having the further recommendation of being strikingly handsome. This handsome plant is an orchis. Several specimens of orchis are to be found around Doncaster, some in dry pasture, some in shady woods, some in rich meadows and one in bogs. The other plant is much less conspicuous. It is the arrowgrass (Triglochin). Now we have in England two species of Triglochin; T. maritimum, growing in salt marshes close to the coast, and T. palustre, growing on marshes in inland localities. The two plants are very similar in general appearance, but are easily separated by the shape of their curpels. [sic]

There is an extensive genus of moths known to entomologists as the Enpicoelias [sic]. They are all of small sizes, and the larvae of all of the different species feed in the stems or seed vessels of various plants. One of these little moths (Enpicoelia vectisana) [see (Gynnidomorpha vectisana)] is common and is generally distributed around the coast wherever there are salt marshes, the larvae feeding in the flower stems of Triglochin maritimum. But this particular species of moth had never before last year been found in any inland locality in England, except Wicken Fen, in Cambridgeshire. One afternoon while I was collecting insects here at Askern bog I took a number of Enpicoelias, which appeared to me to be vectisana, and such they proved to be. Here then is an interesting fact in natural history – a moth supposed to be confined to salt marshes abounding in a small inland bog. How is its presence here to be accounted for? Probably in several ways. No doubt the larvae feed on both species of Triglochin; if it can’t get maritimum it will put up with palustre. Probably the few inland localities were it can be found were in comparatively recent times connected with the sea and supported a maritime flora, and we still have a few species of both plants and insects remaining, such as were able to exist under the changed conditions. In support of this theory it may be mentioned that near Doncaster there are three species of plants to be found in three different localities, and all these species are distinctly maritime in habitat. They are the strawberry trefoil (Trifolum fragiferum) now growing on York-road near the Bodles; the Star of the Earth (Plantago coronopus) at Bessecar; and a grass (Schlerochloa distans) at Warmsworth. It is quite possible also now that E. vectisanan is know to be obtainable in inland localities it will be recorded from other stations, as there are a large number of collectors that only discover facts at secondhand.

On some of the dryer parts of the marsh the moles have been at work casting up the soil in little mounds, and these mole-earths are full of valuable information as to the former condition of the bog. The cast up soil is seen to be a friable vegetable-formed loam, but it is full of shells, many of them broken, many still perfect in form, but nearly all bleached white by the action of the acids in the soil, the coloured epidermis having decayed away. I have found upwards to twenty different species of shells in these mole-earths, and no doubt further research would reveal yet others. These shells are, strictly speaking, fossils. But they are fossils of recent date, probably only been deposited in their present position a few hundred years or even less. Nevertheless, they tell us that some time ago that which is now marsh land was some time ago was actually under water. The water was shallow, and the dry land was close by. How can this be learnt from the shells in the mole-earth? The majority of the shells are those of fresh-water molluscs. There are none of those species that inhabit salt water, but there are a considerable number of those of the terrestrial species. Now all the terrestrial species to be found in the soil of the bog are common at the present time in the immediate vicinity. By searching among the herbage and under stones in the quarry on the roadside above the marsh all these species may be found alive, and if in the place of the bog there was a lake, every heavy rain would wash down numbers of these land shells into the lake, where they would ultimately be drowned and sink into the mud at the bottom. When we come to examine the aquatic species, we find that there has been some change in the species to be found in the locality since they flourished here. All the different kinds to be found in the mole-heaps are well known to be living in England at the present day, but some of them are not now obtainable about Askern. These aquatic shells must have lived and died at the place where they are now found. They could not have been washed by floods as the terrestrial species might, because water will not run up hill and the level of the bog is above the present level of the water in the pools and dykes.

There is yet another object to be found in great numbers in the mole-heaps, which speaks even more eloquently than do the shells to the fact that here was formerly water. These are the nucules of Chara. Chara is a purely aquatic plant, living completely submerged in fresh and brackish water. The nucules are minute void bodies growing on the plants and containing the female reproductive organs, fortunately they are composed of lime, and therefore are not subject to decay. Charas of different species are to be found in plenty growing at the bottom of deep pools about Doncaster and Askern, and here is evidence that they grew under similar conditions where now is comparatively solid earth. I have no doubt that if some of our practical microscopes would examine some of the bog earth for diatoms, they would find them. Here then we have proof that a fresh-water lake formerly occupied the place of the present marsh, and it is quite probable that before the fresh-water lake the land surface was still lower, and that the tides reached up the valley of the Don much further than they do now, and along the margin of the estuary a maritime flora flourished of which, as we have seen, trees still remain.

If now we go towards the pool on the further side of the bog, we shall soon find that there is no hard and fast line to be drawn between land and water. Beside the margin of the pool is a thick growth of sub-aquatic vegetation, and by carefully picking our way we can get near the edge of the open water. All around us is a dense growth of tall reeds, sedges, and other water-loving plants. To enumerate these would be a tedious work, but it is worth while to pick out a few of the more interesting for notice. One of the most conspicuous is the common loosestrife (Lysimachia vulgaris) – an erect downy stem two or three feet high, with whorls of from two to four ovate-lanceolate leaves, and a large terminal pinnacle of yellow cup-shaped flowers. These flowers might, by the uninitiated, be supposed to belong to the buttercup group of plants, and certainly in general appearance they are more like buttercups than are those of the Thalitcrum that we noticed earlier. However, they are not of the buttercup, but of the primrose group. This plant, in its natural wild state, is always found in marshy ground, but under cultivation it will exist, if not thrive, in the smoky atmosphere of large towns, and is a great favourite with town gardeners. Its popular name among them is Golden Rod, but that name really belongs to a totally different plant.

Another very conspicuous and common plant here, although by no means generally common is the Prickley-twig Rush (Cladium marisens). The English name of this plant has one good point and one bad point in it. Prickley is right. Rush, all wrong. The plant is not a rush, but a sedge. The stem is from 2 to 5 feet high smooth and cylindrical and beautifully striated, the leaves are long and slender with very fine tapering points; their edges are very sharply serrated and if the leaf be carelessly handled it will tear the flesh very painfully. The flowers are in a lateral panicle and are dark brown in colour. I recommended this plant to the notice of all who like to decorate their rooms with grasses, reeds, etc.; it is strangely handsome and keeps its form well when dry.

Tey another plant that should be noticed here before we pass on is the Horse bane (Oenanthe lachenalia). This plant is one of the very large order umbelliferoe. An order that includes many plants used as foods, many used as medicines, and many that are dangerously poisonous, and the present species is among the poisonous ones. It has thick round and slightly grooved stems with alternate sheathing leaves which are of a glaucous green colour and very finely divided. The flowers form an umbel and are white. Such a description might apply to many umbelliferoe but the various distinctions in this group of plants are only to be learnt by careful study. I would, therefore, advise all who do not well know the different species to avoid experimenting with any of them internally.

Some curious objects to the stems of rushes arrest our attention; they are silken tubes about one third of an inch in length and covered on the outside with short fragments of grass stems. What are they? They are the dwelling places of the larvae of a moth, and are carried about much in the same way that a snail carries its shell and serving the same purpose as the snail shell. In the case of the snail the shell is really a part of the animal, while these larvae cases are not of the larva but are made by the larva. The tenant is able to quit its house when it likes, though as a matter of fact it lives constantly at home, only protruding its head and front segments in order to feed on the grasses among which it lives. The moth that develops from this larvae if known as Epinepbycha pulla, and it belongs to a very curious group of moths, the Psychidae, the males of which are furnished with well developed wings and are capable of rapid flight. But the females are most domesticated ladies, totally devoid of wings, and with legs so weak that they can hardly crawl. They never leave the case to which their larval existence was passed, and devote their whole energies to laying eggs. We have several species of Psychidae in Britain, but only two are known to occur in Yorkshire. Of these Fumea intermediella is generally distributed, being a woodland species, but Epinoptycha pulla is known in our county only at Askern, and cultivation will probably exterminate it here.

Cultivation of waste land is by no means the only cause of the extermination of species; there are many other causes among the worst of which is inconsiderate and grabbing collecting by persons styling themselves Naturalists, and probably nothing has suffered more from these than have our native ferns. Following the publication of Moo’s splendid monograph of the British Ferns a perfect mania for fern collecting seized the people, Devonshire, the Lake District, Scotland, Ireland and Wales were ransacked for varieties and the consequence to day is that many places that used to be rendered beautiful by the luxuriance of these elegant plants are now stripped of them. Our own neighbourhood has suffered along with the rest. Where are the Harts Tongues of Edlington? The Asplenium trichomanes of Conisbro? Or the Aspidium aculeatum of Levitt Hagg. All gone! But one of our tarer or at least more local species still flourishes here. Perhaps the fernio-mania did not like wet feet and there are certain to be the lot of him who gathers Nephrodium thelypleris.

Here in the bog it flourishes in the greatest profusion but chiefly in the very wet parts. It is an elegant species and has fronds rather narrowly lanceolate and the rachis very long. It differs from all the other British species of its genus in not growing from one crown and forming a circle of fronds, but in possessing creeping stem or rhizome from which the fronds grow at intervals.

Among the rank growth of waterside plants many birds find suitable places for rearing their young. Coots and moor-hens are leading their chicks about the surface of the pool, where they look like so many animated balls of black wool. Here, supported on the strong but flexible stems of the reeds is the deeply cup-shaped nest of the reed-warbler. The sides of the nest are firmly bound to the growing stems and though they may wave to and fro in the wind the cup of the nest is so deep that the contained eggs or young are quite safe. The reed-warblers themselves may occasionally be seen creeping among the water plants and their little twittering song is often heard especially in the evening. While we are watching the young moor-hens paddling about and searching insects there is a sudden rush and swirl in the water and one of the chicks disappears. A pike has got him. It reminds us of the saying attributed to Professor Huxley, “The rule of life is. Let us pray, but you must spell Pray with an e.”

There are hundreds of other things to be seen in the bog, all of them worthy of extended notice but I have occupied quite enough with the few to which I have called your attention. My concluding advice is “go and see for yourself.