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The article presents information on the jubilee symposium convened to mark the 25th Anniversary of the founding of Unit of Comparative Plant Ecology at Sheffield University in Sheffield, England, which fell on October 1, 1986. Topics discussed were a reflection of the Unit's current interests and included overviews of recent work and predictions for the future, both from past and present members of the Unit and from invited speakers. Seventeen papers presented here were delivered to 160 delegates from 15 countries. The main theme of papers presented was interspecific variation in the form and functions of plants, particularly in relation to environmental factor.

A two-day discussion Meeting of the Royal Society, "The Nitrogen (N) Cycle," held in London, England in June 1991. The author reviewed the considerable progress made in understanding the N cycle in agricultural, forest and aquatic systems. The meeting included some discussion of the concerns which were already being expressed at that time over nitrate in water supplies, and the impacts of nitrogenous gases on tropospheric chemistry, the greenhouse effect and the ozone layer. Since then, disquiet over the impacts of nitrogenous compounds on the environment has increased, and numerous papers have been published on many aspects of the problem.

Information about several papers discussed at the 29th New Phytologist Symposium: Stomata in Manchester, England in July 2012 on the global impact of stomatic pores and guard cells is presented. Topics include stomatal development and evolution, climate models and improved crop production. Its logo is also provided which shows the role of such cells in regulating worldwide issues such as climate change and breeding of sustainable crop.

Pollen analysis and radiocarbon dating of profiles from three sites in the Somerset Levels has allowed the construction of both pollen percentage and influx diagrams. The results are used to discuss the timing of vegetational change within the area of study and to quantify further the effect of man on such changes as are recorded. [ABSTRACT FROM AUTHOR]

The article presents two reports, one on a meeting on Physiological Mechanisms in Biotrophy and Hemibiotrophy held at the University College of North Wales, Bangor from April 22-23, 1987, and financed by the Transley Fund and the British Society for Plant Pathology, and the other on the second meeting of the Plant Transport Group held at Oaklands College, Saint Albans, from September 14-16, 1987. The Plant Transport Group was formed in 1985 to promote discussion of current research into all aspects of transport in plants.

The article focuses on the 4th International Botanical Microscopy meeting held in Durham, England between April 7-12, 1991. In recent years, confocal laser scanning microscopy (CLSM) has significantly improved the imaging of biological specimens by optical microscopy, discussion about the technique took place in the meeting. Questions regarding reliability of the Lucifer Yellow-CH dye as a marker in plant cell biology has been examined during the meeting. Cryo-technique for plant biological studies has been also discussed in the meeting.

The article focuses on interdisciplinary research in biology. An interdisciplinary team at the University of Reading, England, is working on a project which seeks to highlight the value to biological research from various approaches drawn from the humanities. The team at Reading has been focusing on two humanities disciplines, history and literature, and providing presentations on those areas that can be relevant for biologists.

The article highlights the conference entitled "Origin and Evolution of Autumn Colours," which was held in Oxford, England in March 2008. David Lee of the Florida International University was keynote speaker, who spoke about the range of pigmentation found in plants from flavonoids in the cell walls of sphagnum and xanthophylls of Zamia. Other speakers at the event and their presentations are reviewed.

The article discusses the highlights of the 17th New Phytologist Symposium held in Buxton, England, in September 2007. The symposium sought to clarify whether systems biology really is a new and exclusive form of biology and how it might benefit biologists. John Sheehy defined a system as a number of interacting elements existing within a boundary which is surrounded by an environment. June Medford provided a glimpse about the cellular circuitry of the plant.

The article highlights the issues that emerged during the 14th New Phytologist Symposium held at the Royal Society in London, England in January 2006. The symposium addressed the broad goal of ecological development. Ecological development aims to close the gap between mechanisms and ecology, and provide a genuinely integrated view of plant development in its real environmental context. Knowledge of genetic mechanisms may be essential in understanding the degree of correlation or independence of plant responses to different environmental factors.

The article presents a report on a joint meeting of the British Bryological Society with the Linnean Society of London held in London, England on May 7, 1987. The Tansley Fund made a significant contribution to the traveling expenses of overseas bryologists invited to speak at this meeting, one of a series celebrating the bicentenary of the Linnean Society of London. It thus became possible to bring internationally well known specialists from the U.S., Canada and Australia thereby adding appreciably to the interest of the meeting. The meeting showed very clearly how far the Bryological Society has moved on from what would have been the prevailing viewpoint and principal subject matter of a comparable meeting 50-60 years ago.

The article presents information about congresses and conventions related to biochemistry held in England in April 1988. The 11th anniversary meeting of the Tetrapyrrole Discussion Group, founded in Britain, and now with a growing European and Northern American membership, brings together plant and animal biochemists, chemists, clinicians and other scientists with a common interest in chlorophyll, haems and bile pigments. This meeting was held in Leeds from April 11 to 12, 1988. Another meeting titled "Advances in Seed Biology," related to topics from biochemistry to ecology was held in Royal Botanic Gardens, Kew, from April 14 to 15, 1988.

Mature apple (Malus domestica Borkh.) trees were exposed to episodes of 100 and 150 nl l-1 ozone in 1990 and 1991 respectively, in open-top chambers at the University of Nottingham, Sutton Bonington Campus, UK. The episodes were for 8 h daily and for not more than 3 d in succession, with a seasonal total of 37 d in each year. Leaf fall was monitored by counting leaves on marked shoots at frequent intervals. A significant interaction between ozone exposure and leaf age was observed: exposure to ozone accelerated autumn leaf fall in old leaves. The relationships between experimental conditions, leaf age and plant material are discussed, and the implications for UK flora are considered. [ABSTRACT FROM AUTHOR]

The results of investigating a series of 11 pollen and stratigraphic profiles in peats along a 350 m stream section are described. Each profile has a small pollen catchment overlapping little with its neighbour's and the diagrams therefore show fine spatial resolution of the vegetational history. Fine temporal resolution is provided by 1 cm, or for certain sections 1 mm, interval samples. There is evidence that during the Mesolithic distinct patches of the local forest vegetation, of the order of tens rather than hundreds of metres in diameter, were managed by burning and the regular lopping of branches, for periods of up to a few hundred years each. Peat inception is thought to have occurred as early as the 9th millenium BP in some parts of the stream and up to 3000 yr later in others. Lopping and burning was the immediate cause at most sites within the channel of the gill, although fine-scale topographic and geological variation affected the timing. The developing peat was bordered by an alder carr in the lower and middle reaches of the stream. Radiocarbon dating of the mid-Flandrian Ulmus decline shows it to he asynchronous. It was caused by a combination of factors including disease and the affect the mesolithic management practices had had on the soil earlier in the Flandrian. [ABSTRACT FROM AUTHOR]

Clonal replicates of Spartina anglica C. E. Hubbard were reciprocally transplanted into cleared plots and undisturbed vegetation in three adjacent zones on the Dee Estuary salt marsh, Cheshire, England. The aim of the investigation was to examine whether clones from these populations show a differential response to the range of naturally occurring environmental variation. Clone survival was significantly lower in the pioneer zone relative to the sward and mature marsh zones and was greatest in plants from the pioneer population in all transplant sites. Tiller number per plant was consistently greater in the pioneer population, increased with increasing marsh elevation and the removal of natural vegetation in the mature zone, and, for the pioneer and mature populations, showed a significant clone × environment interaction effect. The norms of reaction showed marked differences between clones in the pattern of response to environmental variation, but joint regression of clone means on overall means showed that very few clones had a linear response. Several morphological characters showed significant interactions with environmental effects in ANOVA, but only for total plant biomass in the pioneer population did this reflect a linear increase in more favourable environments. Differences in overall stature quantified by the pattern of morphological character correlations indicated the occurrence of different morphological forms within the populations. The differences in performance and plasticity are discussed in the context of the successional development of these populations, and the possible influence of age-related somatic variation. [ABSTRACT FROM AUTHOR]

summary Peroxidase isoenzymes in stem tissue were investigated by polyacrylamide gel electrophoresis in Sorbus populations mainly from Devon, south-west England, A total of 16 bands were recognized, of which 10 were variable between individuals or populations. The sexual diploid species S. aucuparia, S. aria and S. torminalis showed individual variation within populations. Six polyploid microspecies, S. anglica, S. porrigentiformis, S. rupicola, S. vexans, S. subcuneata and S. devoniensis, and an extensive unnamed rupicola-like population on the coast of north Devon and west Somerset, consisted of individuals of essentially identical phenotype (with a few recognizable minor variants). Every microspecies had a distinctive peroxidase phenotype but S. porrigentiformis from Devon was not identical with a specimen from Leigh Woods, Bristol. Microspecies of the S. aria group have various combinations of seven bands which occur in diploid S. aria populations. S. anglica combines 'S. aria' bands with a prominent band from S. aucuparia. S. subcuneata and S. devoniensis possess four or five of the 'S. aria' bands, together with two bands which are apparently constant in S. torminalis; S. intermedia also has a peroxidase phenotype related to these species. [ABSTRACT FROM AUTHOR]

In vivo growth rates of Gongrosira [probably G. incrustans (Reinsch) Schmidle], a cushion-forming fresh-water green alga (Chaetophorales) are reported for the first time. The annual radial growth rate averaged 0·42 mm in a mountain stream from northern England and was positively correlated with water temperature (r = + 0·919, P < 0·05). The colonies were heavily incrusted with calcium carbonate (calcite). Photosynthetic activity probably promotes calcification between the closely packed basal filaments, but most of the precipitation appears to be abiogenic from supersaturated stream waters. Calcified Gongrosira bioherms are also described from a subtropical site in Mexico. The survival period for Gongrosira at the English site was approximately one year, and at both sites Gongrosira was a permanent and significant component of the epilithic algal flora. [ABSTRACT FROM AUTHOR]

A pollen diagram from freshwater sediments resting on glacio-fluvial outwash at Trysull, Staffordshire, England shows a sequence relating to the development of temperate stage forest. Correlation with a nearby Hoxnian site at Nechells, Birmingham is suggested. [ABSTRACT FROM AUTHOR]

From an extensive literature survey and from analytical data of 130 species from the Sheffield flora, the physiological and molecular attributes, and occurrence of fructan are considered. The exceptionally high concentrations of fructan in many native species and its exclusive vacuolar location are noted. In view of the contention that fructan may function in low temperature tolerance, estimates are given of their maximum vacuolar concentration. For most species examined, this is unlikely to make a significant contribution to low temperature tolerance under the field conditions of the Sheffield flora. The association of high concentrations in the shoots of several species with high nuclear 2C DNA values is recorded. It is this correlation which may be of significance to several early-season growing species. By maintaining supplies of fructose and sucrose from vacuoles in tissue undergoing expansion at low temperatures (a feature associated with high DNA values), such species obviate the need for transport of carbohydrate over distance as in starch-storing species. By shortening supply lines at critical cold periods, fructan-rich species may have a considerable advantage over starch-storing, small-celled, transport-dependent species. However, such an advantage is not commonly exploited by the contemporary Sheffield flora. It is suggested that the ecological significance of fructan may best be seen in floras of the past or in contemporary floras undergoing more severe environmental stresses. [ABSTRACT FROM AUTHOR]

The post-glacial pollen stratigraphies of two sequences of lake sediments (Hockham Mere and The Mere, Stow Bedon) are compared. Both suggest displacement of existing taxa when new taxa arrive from their cold-stage refugia and expand their populations. Hockham Mere is within an area of sandy soils, while The Mere at Stow Bedon is within an area of calcareous till soils. There have been differences in the forest vegetation around the two sites for most of the last 10000 years, and the competitive interactions between the forest trees differ also. [ABSTRACT FROM AUTHOR]

An extreme genetic variant ot Urtica dioica L. (stinging nettle), differing from the common plant in its paucity of stinging hairs, tall unbranched growth form, long narrow leaves and late flowering, occurs in large numbers at Wicken Fen, Cambridgeshire, England Evidence from experimental cultivation of plants collected as adults and as seed along a transect across and beyond the boundaries of Wicken Sedge Fen suggests that: (1) Significant gene flow into the Sedge Fen occurs by both seed and pollen transport (2) Pollen flow has significant within population effects also, acting to even out variation expressed in the adult generation. (3) Patterns of variability in adults do not indicate that natural selection is acting to limit the range of variability contained in the seed population. (4) Selection may, however, be occurring, since for this long-lived perennial, patterns of variability may be more related to historical factors than to current ones. [ABSTRACT FROM AUTHOR]

Analysis of the basin morphometry of Hockham Mere suggests that the lake basin is of a shape in which sediment is likely to be focused. Consideration of three long pollen diagrams through the deposits shows that focusing of organic post-glacial sediment began at about 9255 B.P., and continued until the lake basin had filled, during the mid post-glacial. The sediments deposited before 9255 B.P. are highly inorganic, and have remained concentrated near the edge of the basin, where they were initially deposited. The pollen accumulation rate diagram, from the deepest part of the basin, cannot be understood without considering the changing pattern of sediment distribution within the lake, and it is suggested that pollen concentrations may yield a more reliable interpretation of the development of vegetation in the surrounding landscape than can be obtained from pollen accumulation rates. [ABSTRACT FROM AUTHOR]

The Blacklane Brook profile, first published in 1964, has been re-examined and given firm dating in the light of the archaeological and fossil tree-line interest that the profile has generated. A much fuller record of the open vegetation of Flandrian I is presented, and many new pollen types for the site are indicated. The recession phase noted in 1964 is found in this profile also and is dated to begin ca. 7760 BP. It is thus placed well within the Mesolithic cultural period. The resolution of the pollen diagram and the difficulties of interpretation of upland sites do not make it possible to make firm statements about the location of the tree-line at different periods. [ABSTRACT FROM AUTHOR]

Fossil records of Cannabiaceae pollen and Cannabis achenes from Flandrian deposits at three sites in eastern England are presented as further evidence for the past cultivation of this crop. It is suggested that retting of hemp to extract fibre was carried out at each of the sites. [ABSTRACT FROM AUTHOR]

Failure of regeneration of Tilia cordata in north-west England is associated with almost complete sterility of the seeds. Between 1964 and 1979 significant numbers of fertile seeds were recorded only after the exceptionally warm summer of 1976. In contrast, large or moderate crops of fertile seed were produced at sites in central and southern England in at least 8 of these years. Comparative studies of pollination, fertilization and seed development at sites in north-west England, central England and northern France show relatively small differences in the proportions of flowers which are pollinated but significant differences in the rates of extension of pollen-tubes. In samples collected in 1977 from north-west England germinated pollen was present on most receptive stigmas but many pollen-tubes extended only a short distance down the style and the few which reached the base appeared to be arrested in the ovary wall. In French samples pollen had germinated on all receptive stigmas and numerous pollen-tubes had reached the ovary within 2 days of pollination. These differences cannot be attributed to variation in the incidence of self-pollination, as at least some trees of T. cordata in northern populations are almost certainly self-fertile. The differences are correlated with temperatures at the time when the samples were collected. When pollen-tubes are growing in sucrose solutions, their rate of extension shows a large response to temperature over the same range (15 to 25 °C). Analysis of records shows that temperatures in north-west England at the time of flowering are frequently too low to permit fertilization. This is confirmed by studies of the development of ovules. Although a high proportion of ovules in T. cordata lack embryo sacs, normally at least one is functional in each ovary. In over 90% of fruit formed in north-west England, embryos are contained in none of the 10 ovules. [ABSTRACT FROM AUTHOR]

Adjacent species-rich and species-poor areas of a limestone outcrop were investigated in a heavy metal mining complex on Grassington Moor, Yorkshire, England, to determine reasons for the differences in their floras. Levels of soil lead, zinc, nitrogen, phosphorus and potassium were determined and the activities of the enzymes urease, acid phosphatase and dehydrogenase in the soil were measured. Soil respiration rates were also determined. The percentages of the variation in species-density accounted for by each factor were determined using a step-wise multiple regression technique. Binding of lead in organic forms resulting in low levels of available lead, together with higher levels of the major plant nutrients, were probably the main factors enabling a species-rich community to occur on one part of the outcrop. Possible ways in which the differences in habitat became established are discussed. [ABSTRACT FROM AUTHOR]

The infection of populations of Silene dioica by Ustilago violacea was studied in four areas of north-west England. Infection showed wide variation in each area but was not readily related to shade stress from trees or shrubs, nor was percentage infection simply related to shoot density. Infected male shoots predominated early in the season, but later, infection was greater in females. Overall, female plants had a higher percentage of infection than males and, in some populations, over a third of the reproductive capacity was lost. Infection reduced the growth of male plants but produced a large increase in the number of flowers on female plants. The results are discussed in relation to the spread of the disease and to the effects of the fungus on the population dynamics of S. dioica. [ABSTRACT FROM AUTHOR]

The vegetational history of Crose Mere, north Shropshire, is reconstructed by means of pollen analysis, lithostratigraphy and radiocarbon dating. Pollen diagrams from a core representing the Flandrian and Late Devensian are presented. Eleven radiocarbon dates were obtained from the Flandrian and these allowed the estimation of pollen deposition rates from pollen concentrations. The pattern of vegetational changes shows close similarities with those from the lowlands of north-west England notably the appearance of Pinus sylvestris after Corylus avellana, Ulmus and Quercus in the forest succession. The effects of man on the environment are traced and four main agricultural episodes are distinguished after the 'elm decline' at about 5300 B.P. Comparison of pollen percentage and absolute data highlights the problem of interpreting pollen deposition rates from a basin with uneven sedimentation and the possibility of resuspension of freshly deposited sediments. [ABSTRACT FROM AUTHOR]

Pollen originating from small populations of Tilia cordata is largely deposited within a few hundred metres of the trees, so that their presence can only be detected by pollen analysis at sites within distances of this order. Pollen diagrams from such sites show a continuous curve for Tilia pollen extending to the present surface, although the values may be only about 1% of arboreal pollen. Pollen analysis shows that T. cordata was present in the Lake District by about 5000 to 4800 B.C.; it then became plentiful in the southern valleys and extended to reach its present north-western limit, or just beyond, by 3100 B.C., when migration ceased. While the tree was extending its range, it must have been able to produce frequent large crops of fertile seed but subsequently regeneration from seed ceased. After 3100 B.C., the proportion of its pollen initially may increase but then generally decreases. Although there are small recoveries at several horizons, these are not certain evidence of reproduction by seed. Failure to produce fertile seed renders the species particularly sensitive to woodland clearance and has resulted in a decrease in abundance within the Lake District and its virtual extinction in west Yorkshire and south Lancashire. [ABSTRACT FROM AUTHOR]

Pollen influx data from the Flandrian peat deposits of the Somerset Levels, south-western England, are compared with other pollen influx data for peat and lake deposits. Peat deposits are found to have a much smaller annual recruitment of pollen than lake sediments. This difference is attributed to the absence of pollen contributed by inwash or stream inflow into a peat, particularly a raised bog peat, deposit. [ABSTRACT FROM AUTHOR]

Details are given of four interesting new palaeobotanical records from an Ipswichian (last) Interglacial site in the East Midlands of England. The taxa are considered in the context of the site, and a brief review is presented of their Tertiary and Pleistocene history and present ecology, with some discussion of the phytogeographical implications. [ABSTRACT FROM AUTHOR]

Interglacial deposits resting on glacial till and overlain by fluviatile sand and gravel 2 km (1.5 miles) north-north-west of Stevenage are shown to be of Hoxnian age. The lower part of the deposit consists of calcareous silty clay formed under late-glacial and early interglacial conditions with Hippophaë shrubs and Betula woodland in a shallow water pool which contained an abundant flora and fauna. The upper part of the deposit consists of organic sediment and represents the second half of the interglacial during which coniferous trees were dominant. The fragmentary sequence, which is also found at other Hoxnian sites in Hertfordshire, is shown to result from water level changes. The recognition of these changes elsewhere in Eastern England indicates that they may be climatically controlled and thus reflect periods of alternating moister and drier conditions. [ABSTRACT FROM AUTHOR]

The intensity of vesicular-arbuscular mycorrhizal infection was assessed in the major vegetation types of east-central England. All of the most important species of grassland, scrub and woodland were mycorrhizal and each individual of any species normally carried a heavy VA infection. Members of the Gramineae were particularly heavily infected, In limestone grassland, infection extended to members of the Cyperaceae and Juncaceae. Infection levels were high throughout the year, the highest levels occurring in the most nutrient-stressed situations. Mycorrhiza develops soon after germination, often while seedlings are still in the cotyledon stage. Since numbers of viable Glomus type spores are low, infection is thought to arise from root to root contact rather than from spores. The ecological implications of the widespread infection are discussed. [ABSTRACT FROM AUTHOR]

When plants of Sedum rosea (L.) Scop. and S. telephium L. ssp. fabaria Syme are grown in competition at different altitudes it is found that the growth of the species is affected differentially. This effect is such that at low altitudes S. telephium is a larger plant than S. rosea, while the reverse is the case at high attitudes. The observed differences are caused by a marked sensitivity of the growth of S. telephium to differences in altitude, whileS. rosea is very insensitive. The most probable cause of these responses would appear to be differences of climate. The influence of altitude in northern England on air temperature, saturation deficit and irradiance has been investigated in order to establish the magnitude of the differences which may cause these responses. [ABSTRACT FROM AUTHOR]

A number of new plant records are described from deposits of the Cromer Forest Bed Series of East Anglia. Each species is discussed in relation to its context and to its stratigraphical position within the series. Some aspects of the flora as a whole are provisionally described. [ABSTRACT FROM AUTHOR]

The results of 14C- and 210Pb-dated pollen profiles from the Forest of Bowland, Lancashire are presented, covering the period from the late Iron Age up to the present day. Two notable features of the pollen profile are the apparent lack of a period of large-scale forest destruction during the time of the Norse invasions and the substantial phase of tree clearance towards the end of the Iron Age period. The evidence suggests that the Viking invasions into Lancashire may not have been as destructive as once believed. The invasions were probably gradual, possibly localized (certainly as regards the Bowland area) and seem to have occurred alongside existing populations. Previous pollen-analytical evidence regarding the Iron Age peoples of north-west England has supposed them to have had little effect on their surrounding vegetation. It is now suggested that forest clearance previously assigned to the Romans in north-west England is of Iron Age origin. The pollen profiles presented also reflect several changes of socio-economic conditions that have affected rural populations in Lancashire during the last millennium. An important example is the decimation of populations during the fourteenth and seventeenth centuries. It is suggested that these were caused by the development of subsistence economies, leading each time to a Malthusian crisis. These population declines may also have been exacerbated by outbreaks of plague. The fall in population at both times, is clearly reflected by rising arboreal pollen values, indicative of slackening rates of forest clearance. [ABSTRACT FROM AUTHOR]

Information about the topics discussed on the plant temperature response networks conference in September 2009 at the Cathedral City of Durham in England is presented. It mentions that the meeting was organized by Heather Knight of Durham University in Durham and Kerry Franklin of the University of Leicester which involves a two-day workshop on the effect of temperature on the function of plants. It cites that the meeting aims to achieve diversity with the help of scientists in Great Britain.

The article highlights the 15th "New Phytologist" Symposium on Networks in Plant Biology of the Linnean Society in London, England in January 2006. A theme running throughout the symposium is the idea of the level of detail necessary to understand a systems behavior. The topics under discussion ranged from the entire globe to the internal workings of a single cell, but in each case the question of how much detail we need to know about a systems components and how they interact to understand its behavior arose again and again.

The article presents a report of the meeting on infraspecific classification of wild and cultivated plants that was held from September 26-28, 1984 in Oxford, England. The meeting was sponsored by the Systematics Association. The three day international symposium discussed ways in which wild and cultivated variants of plant species are classified. It was successful in bringing together four normally separate professions of plant taxonomists, foresters, crop and horticultural botanists, and plant breeders.