Meeting at University College, LondonSource: Journal of Animal Ecology, Vol. 19, No. 2 (Nov., 1950), pp. 204-206Published by: British Ecological SocietyStable URL: http://www.jstor.org/stable/1530 .

Accessed: 08/05/2014 04:19

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal ofAnimal Ecology.

http://www.jstor.org

This content downloaded from 169.229.32.137 on Thu, 8 May 2014 04:19:03 AMAll use subject to JSTOR Terms and Conditions

[ 204 ]

BRITISH ECOLOGICAL SOCIETY

MEETING AT UNIVERSITY COLLEGE, LONDON SATURDAY, 22 OCTOBER 1949

A meeting of the Society was held on 22 October 1949, in the Department of Botany of University College,

London, by kind permission of Prof. W. H. Pearsall. The President, Mr C. Elton, took the Chair at 11 a.n.

and Prof. A. R. Clapham made a brief introductory statement pointing out that the chief aim of the

Meeting was to focus attention on an important activity of the Society, the publication of the Biological

Flora of the British Isles. The speakers would assist other contributors by indicating the kinds of problems

encountered and the ways in which they could be tackled; and would themselves benefit from the dis-

cussions. But the Biological Flora was not be be regarded merely as an end in itself; it was intended that

the accounts should be valuable sources of information for workers in many fields of biological research,

and members would no doubt hear much of great interest and importance to themselves as ecologists.

The programme had been arranged to cover as wide a range as possible. Juncus squarrosus and Calluna

were common and widespread plants of considerable ecological significance, Lloydia serotina was an ex-

ceedingly rare plant and Epilobium pedunculare an established alien, while the aquatic Veronicas presented

some taxonomic problems. The first contributor was Prof. W. H. Pearsall, who spoke on Juncus squarrosus. He stated that this

species was specially prominent in areas which had been subjected to human interference. His interest

had first been aroused by its abundance on Tan Hill, between Swaledale and Upper Wharfedale, and there

it marked areas formerly dug for surface coal, where it had persisted for the 150 years which had elapsed

since digging had ceased. It was a characteristic plant of heather moors suffering from over-burning and,

with Nardus stricta, of Festuca-Agrostis pastures over-grazed by sheep. It grew usually on 'mor' peat less

than 2 ft. thick ahd of pH 3-5-3-8, and sometimes on extremely leached mineral soil, but was only an

occasional plant of deep bog peats. Its substrata were usually saturated with water during the winter but

were oxidizing in summer. The chief associates of Juncus squarrosus were Nardus stricta, Eriophorum

vaginatum and Polytrichum commune, all species with very low nutrient requirements and all indicators

of anthropogenic influences which had reduced the nutrient level of the soil.

Germination tests showed an average viability of about 5000, but percentage germination varied

strikingly with the substratum and with pre-treatment. Maximal germination (90-100%) was obtained

in raised-bog sphagnum peat of pH 3-97, with or without pre-treatment by freezing. On Eriophorum

vaginatum peat of pH 3-28 germination was poor (5-10%) without, but quite high (30%o) with, previous

freezing. On fen peat of pH 6-56 germination fell to about 25%, and on peat of pH 7 60, over marl,

there was no germination at all. Juncus squarrosus grew in every vice-county and at all altitudes from sea-level to 3500 ft. There was

a reduction in stem length, number of flowers and number of seeds with increasing altitude. Thus average

stem length fell from 32 cm. at 700 ft. to 17-18 cm. at 3000 ft.; and ripe seeds were usually not found at

altitudes above 2700 ft. though some were collected at 3400 ft. in 1947. In one and the same year 80%

germination was obtained from plants growing in Festuca-Agrostis grassland and none from plants on

Eriophorum peat. No fungi attacked Juncus squarrosus, but white larval cases of a small moth, Coleophora sp., might be

seen on inflorescences of plants growing at altitudes below about 1600 ft.

In the lively discussion following the paper, P. W. Richards, A. R. Clapham, H. Godwin, A. J. Wilmott,

C. Elton, A. S. Watt, N. Woodhead, C. Gimingham and Miss S. Champness took part. Mr C. Gimingham next gave his account of Calluna vulgaris, a plant of considerable taxonomic and

phytogeographical interest as the only species of its genus, and ecologically important as a dominant of

the Atlantic heaths. It was of interest, too, as an hygrophilous mesophyte with xeromorphic characters,

and it had great agricultural and aesthetic value. Although it extended from the arctic circle in Iceland

and north Scandinavia to Morocco and the Azores, and from the Atlantic seaboard to just beyond the

Urals, it was ecologically important only in a restricted area in north-west Europe where it found its

This content downloaded from 169.229.32.137 on Thu, 8 May 2014 04:19:03 AMAll use subject to JSTOR Terms and Conditions

British Ecological Society 205 characteristic climatic requirements, a high atmospheric humidity with no period of drought and an absence of prolonged low temperatures. In this country young plants on well-drained soils had suffered from the drought of 1949, and there had been many records of frost damage. Dr A. S. Watt had concluded that it could not survive in mountain areas where snow lay for long periods. Its chief habitats in the country were lowland and upland heaths and moors, bogs, woods with a light or interrupted canopy and sand dunes. The soil was always poor in lime and other bases and acid in reaction. Calluna would tolerate a light intensity about 50 % of full daylight but not one of 30 00. It was calcifuge and most plants had a systemic mycorrhizal infection. It grew badly in calcareous soils or in acid soils supplied with calcareous water, and its usual pH range was 3 4-5-9, with an optimum at c. pH 4-4. Its rate of transpiration per unit weight was about average, but it seemed to have some capacity of controlling its rate of water loss.

One of the most striking features of Calluna was its remarkable plasticity in growth form. It was typically a compact hemispherical shrub, but it developed a long slender 'trunk' and a small crown when in dense stands, and became open and straggly or more or less prostrate at high altitudes. Grazing by sheep or rabbits and burning might lead to a bushy or prostrate form. Experimental treatment of young plants by cutting shoots back with scissors had led to the spreading habit and regular pinnate arrangement of tertiary branchlets found in many burnt or grazed areas. A more intensive grazing or clipping caused the production of numerous short ascending branches so that plants ultimately acquired a small button- like form. The effect of shade was the production of weak stems with long loose branches so that the plants fell open at the centre and allowed lichens and mosses to establish themselves there. Calluna communities might die out over large areas if they became even-aged as the result, for example, of simultaneous establishment after fire and so became uniformly susceptible to specially unfavourable climatic effects. The seeds did not seem to require light but their germination occurred sporadically over prolonged periods, up to 3 years from the date of sowing. Dr Poel had found germination at acidities ranging from pH 3 to 10, with optima at pH 4 and 8.

In the discussion, Dr Watt stated that there seemed a considerable genotypic variability in the Calluna of Breckland, affecting the hairiness, the colour of leaves and flowers and the direction of growth of lateral shoots. This seemed to contrast with the limited genotypic variability reported from north Scotland. In reply to Mr A. J. Wilmott, Mr Gimingham agreed that adult plants can send functional roots down into limestone or chalk and thought that the calcifuge habit arose from the restricted tolerance of seedlings. C. Elton and J. L. Harley also took part in an interesting discussion.

Mr J. H. Burnett opened the afternoon session with his talk on Veronica beccabunga, V. anagallis- aquatica and V. aquatica (whose correct name would probably turn out to be V. catenata Pennell). V. becca- bunga was easily distinguishable from the other two by its broad petiolate leaves. V. anagallis-aquatica and V. aquatica had been confused in the past and were certainly much alike, but they could be separated by several characters. Most obviously the flowers of anagallis-aquatica were usually pale blue and those of aquatica were pinkish. Other useful characters were the ascending pedicels, magenta anthers and capsules narrowed below in anagallis-aquatica, contrasting with the horizontally spreading pedicels, reddish anthers and capsules not narrowed below in aquatica. Moreover, anagallis-aquatica differed in its broader leaves, denser inflorescences with more numerous and larger flowers, and its shorter and narrower bracts. An interesting biological distinction consisted in the frequent infestation of the ovaries of anagallis-aquatica and of its sterile hybrid with aquatica, but never of aquatica itself, by the gall-forming weevil Gymnonetron villosulum.

Veronica beccabunga, the commonest of the species, had been recorded from every vice-county, while the other two species had a more patchy distribution as judged by information so far obtained, with anagallis-aquatica appearing to reach farther north (to the Shetlands). But it seemed likely that fuller data would show that all three, with the hybrid, occurred in every vice-county.

All were plants of open marshy base-rich habitats, especially by streams on the broken trampled soil between reed swamp and the closed turf of meadow or pasture. V. beccabunga was distinctly more shade- tolerant than the other two. All set a good deal of seed but seedlings had been observed only on a single occasion and it seemed that reproduction was almost entirely vegetative. V. beccabunga would root readily even from internodal fragments no more than 1 cm. in length, and its greater abundance might be relatable to this capacity which was not shared by the other two. All, however, put out short leafy

This content downloaded from 169.229.32.137 on Thu, 8 May 2014 04:19:03 AMAll use subject to JSTOR Terms and Conditions

206 British Ecological Society lateral shoots from the base of the stemn in early autumn, and these units became detached during the

winter to form new plants in the following season. All, too, could flourish when submerged in fast-flowing

water more than 50 cm. deep, the leaves then being broad and thin and only the inflorescences being

emergent. In the discussion which followed Dr R. W. Butcher said that he had seen healthy rosettes in

much shallower water in some Hampshire rivers. C. Elton, A. J. Wilmott and W. B. Turrill also

contributed. Miss A. J. Davey followed with an account of Epilobium pedunculare as a British plant. This native of

New Zealand was first observed in the British Isles in 1911, when it was discovered near Ardrishaig in the

Clyde valley. At first named E. nummularifolium, it was now clear that all naturalized plants so far

collected belonged to the different species usually called E. pedunculare, characterized by having a glabrous,

not cinerascent-pubescent, capsule. It was a small creeping perennial, rooting at the nodes. It favoured

moist well-drained and often stony substrata, especially by streams and waterfalls and commonly at

considerable altitudes (to 1500 ft.). Its flowers were axillary, with long slender erect peduncles. They were

self-pollinated and set copious seed almost all of which germinated if sown immediately but not, apparently,

if kept. The remarkable feature of the species was its rapid spread in recent years. For 20 years after its

first appearance it remained a rare casual in and near the Clyde district, but from 1930 it extended in

range and quantity so greatly as to become a locally abundant plant. It was now known from Raasay

southwards to Cornwall and had been recorded also from near Aberdeen, Newcastle-upon-Tyne, Buxton

and Tunbridge Wells, and from four Irish counties, Antrim, Tyrone, Fermanagh and Donegal. There were

scarcely any records from the eastern side of the country, and it was said to be unable to maintain itself

in the neighbourhood of Newcastle-upon-Tyne. It seemed susceptible to drought and its preference for

subalpine and western coastal districts might be related to this. A point of interest was its tolerance of

such unpromising habitats as slate waste and china clay. In a long and active discussion it was pointed

out that it must have been introduced as a living plant and probably as an alpine species for rock-gardens

and walls. The related E. nummularifolium was certainly to be seen in gardens.

The last contribution was by Mr N. Woodhead on Lloydia serotina, a plant strikingly different from

Epilobium pedunculare in that it had remained in the same localities for 200 years and had shown no

sign of spreading. It was confined to four precipices in the mountains of Carnarvonshire, was extremely

rare and was decreasing. It was named by Salisbury in 1822 after Edward Lhwyd, Curator of the Ash-

molean Museum towards the end of the seventeenth century, who sent plants for Ray to describe. It was

an inconspicuous plant whose small whitish flowers were open only during about a fortnight between

mid-June and mid-July. The small bulbs produced three leaves annually, two slender grass-like foliage

leaves and an outermost nutritive scale leaf which was apparent only in June, becoming shrivelled in

July. The bulbs projected for much of their length beyond the surface of the substratum, and successive

bulbs formed an obliquely ascending sympodium bearing six functional roots of the current season and

numerous persistent older roots. No insects had ever been seen to visit the flowers nor had any ripe fruit

ever been found in this country, and it appeared to maintain itself vegetatively. Occasionally daughter-

bulbs were produced in the axils of both foliage leaves, this constituting a means of vegetative multiplica-

tion. Its four British localities were all on precipitous north-facing volcanic rocks at 1800-2400 ft. It was

here protected against both insolation and the full force of south-westerly storms, but it was rarely covered

with snow. It was to be found in 'finger-hold grips' and narrow vertical crevices, either alone or with

Rhacomitrium lanuginosum, or sometimes with Festuca ovina, Silene acaulis, Minuartia verna, Sedum

rosea, Thalictrum alpinum, Oxyria digyna, Frullania spp., Campylopus sp., etc. A problem of great interest

was the history of the species as a British plant. Could it have immigrated since the retreat of the ice, or

had it survived through one or more glaciations? Its world distribution was markedly discontinuous in

the mountains of central Europe and central Asia, in northern Siberia and in five of the western states of

the U.S.A. In an active discussion it emerged that the Swiss habitats of Lloydia were commonly on north-

facing slopes but by no means always so, and that the bulbs were often buried at least 2 in. below the

surface of a black humous soil. It was also pointed out that the associates of Lloydia were mostly plants

favouring a base-rich substratum, and that the volcanic rock on which it grew was in fact basic.

The Meeting concluded with an expression of the thanks of the Society to the speakers, and to Prof.

Pearsall for once again extending to the Society the hospitality of his Department.

This content downloaded from 169.229.32.137 on Thu, 8 May 2014 04:19:03 AMAll use subject to JSTOR Terms and Conditions