The Plants of a Silted Pond

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TWO DAYS AMONG THE BUTTERFLIES IN SUFFOLK.

A better picture of the Elysium Insectorum that Suffolk constituted eighty years ago would be hard to find. We have lifted it, to illustrate " the comparative past rarity of Animals " in Suffolk, verbatim et literatim, from 'The Substitute' 1857, p. 151, and supplied the name of the Author, a Student of British Lepidoptera and Coleoptera, who lived at Harwood Place, corner of Rye Lane, Peckham, S.E., from the Entom. Annual 1860, p. 8. Where are the three distinct localities, those of W-album, of Melitcea athalia (now extinct here), and of th Purple Emperors ?—Ed.]

THE PLANTS OF A SILTED POND.

BY LORD CRANBROOK, R.A.

THE Lake at Great Glemham is an artificial piece of water, some three acres in extent, fed by a stream draining a shallow valley which is about two and a half miles long. This valley lies in the parishes of Cransford, Glemham Magna and Parva, Mariesford and Sweffling, in an agricultural district : arable land predominates, but there are some permanent pasture and a certain amount of woodland. The soil is moderately heavy clav on the sides and at the head of the valley, lighter and more mixed on its floor. The stream runs only during periods of fairly heavy rainfall, being fed entirely by surface water and land drains, though it brings with it a considerable amount of detritus when running. The Lake is nowhere very deep and has always had a tendency to silt up, so that, in the past when labour was cheap, it has been cleaned out at somewhat frequent intervals, the last occasion being some time about 1905. Since the introduction of Tyf.ha latifolia, L., in 1914, this silting-up process has been more or less confined to the upper end, so that by 1933 a piece of ground that is some quarteracre in extent has been gained from the Lake where, twenty years before, there had been eighteen inches to two feet of water ; and in that year, a list was made of the dicotyledons found upon this new ground, which list is annexed to my paper.

During the dry summer of 1934-5, some stock were able to get access to the Bulrushes from the lakeside, while a protecting fence was broken down the earlier year, so that almost all the Typha plants had been destroyed by the end of 1935. Those remaining, out of reach of the cattle, were pulled out to prevent the entire Lake from silting-up. This loss of cover has had a marked effect upon the other Flora, and those plants which had disappeared by the summer of 1936 are marked in the annexed list. \

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The new piece of ground is roughly triangular in shape, with the stream's bed running through i t : the base is bounded by the Lake, and the two sides by parkland which has not been ploughed within living memory. T h e heavier particles carried down by the stream have naturally tended to be deposited at this point, so that the soil is somewhat sandy. DĂźring summer the whole of it is some feet above the Lake water-level, though 1936 was an exception, of course; during the winter the whole is under water at times of very heavy rainfall, and then half is probably more often under water than dry. For the purpose of making the catalogue, the boundaries have been taken to be the summer water-level at the base of the triangle and the old lake-sides which are clearly defined.

In trying to analyse the list and to speculate upon the sources of the various plants, I think it reasonable to divide them into four classes, though many can legitimately be placed in more than one class : fa) Water-loving plants; (b) Weeds of grassland ; (c) Weeds of arable-land ; (d) Plants from woodlands and waste places. There is no plant in the catalogue which is not found at other places in the Valley.—Of (a) the Water-loving plants, all those noted in the catalogue also occur elsewhere in the valley.—It seems probable that the seeds of (b) Grassland Weeds could very easily have been carried on the feet of cattle, and I am led to believe that this must be so by the occurrence of Coronopus didymus, Sm., upon that portion of the ground which was not fenced. This is not a common plant, hut it is found in fair quantities near a cattle-drinking trough about two hundred yards from the piece of ground under survey. Cattle-borne seeds, of course, cannot be the only source : I have found portions of plants in the hooves of horses and feet of cattle, which would readilv drop off and take root. Probably some of the compositce, and certainly Acer campestris, would arise from wind-borne seeds, while the stream would tear off and carry down pieces of turf containing other plants; but the fact that Coronopus didymus is an annual, unlikely to survive rough transplanting and extremely unlikely to be carried by winterflood or to be eaten and voided by birds, seems to point to the fact that some seeds are transported by cattle and have been the origin of certain plants in the catalogue. That the stream has brought other plants, I know: both Salix-species were carried down as branches in one of the winter floods about 1915 ; and in 1933 there were two garden plants, a double Daisy (Bellis sp.) and a double-Daffodil (Narcissus sp.), which probably came from the village of Great Glemham where the stream runs beside several cottage-gardens and receives a good deal of house and garden refuse : in fact, analysis of tins and bottles swept thence into the Lake would give a foreign scientist excellent data upon the modern Englishman's meals ! I do not

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THE PLANTS OF Ă„ SILTED POND.

think, however, that many plants would survive any very considerable transit by the stream: bulbs, Docks and Willem branches would probably do so, but ordinary herbaeeous perennials would be so beaten about as to be incapable of rooting and living in winter: while, when the stream does seep in summer, it is not usually with enough velocity to uproot and carry away living plants. Hence none of the annuals and few of the perennials have, probably, been carried by the stream as living plants, though seeds could easily be so carried.

Other possible agencies are seeds, eaten and evacuated by birds and cattle. I do not think that the passing of seeds by cattle can have had much effect upon the ground under survey: in winter, when seeds from late-cut hay might be present in considerable quantities in cattle-excreta, the water keeps cattle away ; while in summer, cattle tend to avoid tough and overripe herbage. That birds evacuate seeds is well known, of course : but the effect cannot be estimated.

It is unlikely, from the topography of the valley, that many living (c) Weeds of arable-land could have been carried by the stream and it seems likely that the majority have arisen from seeds washed from the fields into the stream and thence down to the lake : in this class, again, the work of birds must not be forgotten though still ungaugable. All the species of (d) Plants from woodlands and wastes could have been carried down alive by floods, as the banks of the stream are rough and bushy from a point 150 yards above the lake; but water-borne seeds would appear to have played a larger part for the reason noted under (b) above.—To sum up, it seems likely that the principal agent in the c.olonisation of this new piece of land has been the stream which made it and that mainly by carrving seeds, though also carrving living plants : the wind, cattle, and birds have also probably played some part. As many other species are found along the side of the stream and have not been discovered upon the area under survey, it would seem possible that the seeds of those enumerated are better able to resist adverse conditions than some of their competitors.

It is unfortunate that, during the twenty years through which this piece of land was being built up, it was not possible to make a yearly survey and note the arrival of new plants : such a survey would have been of great interest and have given much greater information on the colonising abiiity of some dicotyledons than this paper is able to do. T h e reverse process, the disappearance of some plants owing to the loss of cover and the treading and grazing of farm stock, is not of so much interest.

T h e extermination of Solanum dulcamara, for instance, is

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only what one would expect; and doubtless, in the course of a few ycars, the Flora of this piece of land will become uniform with that of the surrounding parkland.

CATALOGUE

(sec. London Cat.).

Ranunculus acris, bulbosus, ficaria and *circinatus; Papaver rhceas (one plant); Radicula Islandica, Druce ; Capsella bursapastoris; Coronopus didymus and procumbens, Gilb.; Cerastium vulgatum, L., Geranium Robertianum, Erodium cicutarium, Acer pseudo-platanus (seedlings only), Medicago lupulina ; Trifolium pratense and r e p e n s ; Potentilla Anserina and reptans ; Dipsacus fullonum* (one p l a n t ) ; Bellis perennis, Gnaphalium uliginosum, Achillea millefolium; Seneciรถ Jacobsea and vulgaris; Carduus crispus* ; Cirsium lanceolatum*, arvense and palustre* ; Centaurea nigra, Leontodon autumnalis, Taraxacum vulgare ; Myosotis palustris and versicolor ; Solanum dulcamara* and n i g r u m * ; Veronica beccabunga, anagallis, scutellata and agrestis ; Mentha piperita and aquatica, L. ; Bartsia odontites*; Plantago lanceolata, media and *major ; Chenopodium polyspermum; Polygonum persicaria and aviculare; Rumex crispus and acetosa; Salix fragilis and caprea.

HUNTING ELEPHANTS in 1936.

BY THE REVD. A .

H.

PAGET W I L K E S , M . A . ,

(Member

M.B.O.U.,

etc.

1932-3).

THF. best time of year to shoot African Elephants is from December to April when the grass has been burnt off, the rains are over, and both water and grazing are becoming increasingly local, f o r the movements of all game are thus more restricted than when grass and water may be found everywhere.

On 1 January last my wife and I had a report of a small herd of Elephants' feeding and sleeping regularly in the River Ii valley, not very far from this mission Station where I write at Movo, which is situated in the West Nile area of Uganda, comprised in what used to be known as the Lado Enclave.

That night we sent out a scout to ascertain the herd's movements and early in the morning be returned saying he had seen the Elephants moving about that valley. Taking his word we went with gunbearers bv car along the main road south f r o m Moyo. At a point which he indicated we stopped, having come within easy distance of the Ii River, and looked a r o u n d ' t o see