bluuebunny/crossref_metadata_2025_split huggingface dataset:
SOME ASPECTS OF TXONOMY IN THE CRYPTOPHYCEAE
Authors: SANTORE U. J. 
Published: May 2006

SummaryThe unique and diagnostic characteristics of the Cryptophyceae are discussed and present knowledge of their taxonomy is summarized. It is proposed that the pigmented organisms can be assigned to four genera,Hemiselmis, Chroomonas, CryptomonasandPyrenomonasnom. nov.; the characteristics of these genera are reviewed. The validity of the pigmented generaIsoselmis, PlagioselmisandRhodomonasand the apochlorotic generaChilomonas, CyathomonasandPhyllomitusis considered and present knowledge of their taxonomy is summarized.
RELATIONSHIP BETWEEN MORPHOLOGICAL ADAPTATION TO GRAZING, CARBON BALANCE AND WATERLOGGING TOLERANCE IN CLONES OF DACTYLIS GLOMERATA L.
Authors: ETHERINGTON JOHN R. 
Published: May 2006

SummaryClonally‐propagated individuals of Dactylis glomerata L. derived from two contrasted habitats, respectively, moist soil with no grazing and drought‐prone soil under intense grazing, were tested for tolerance of waterlogging in soil culture. The clone of dry soil unexpectedly proved much more tolerant than the clone of moist soil. Measurements of 24 populations of D. glomerate grown in an experimental garden showed that the grazing pressure in the original habitat is reflected very strongly in the morphology of the garden‐grown plants. Adaptation to grazing comprises a short and narrow‐leaved, prolific tillering habit with production of very short inflorescences. Heavy grazing, or the cutting regime imposed in the waterlogging trial, is likely to do more damage to the upright, long‐leaved morphs of the ungrazed site. Measurements of carbon balance in intact plants and in defoliated tillers support this interpretation and also suggest that the larger oxygen consumption of the massive leaf bases of the ungrazed form might limit root penetration in oxygen deficient conditions. The greater length of roots in the dry soil clone is also discussed as a possible adaptation to water shortage in its cliff ledge habitat.
ON THE ECOLOGY OF SHORT‐LIVED FORBS IN CHALK GRASSLANDS: LIFE‐HISTORY CHARACTERISTICS
Authors: VERKAAR H. J. , SCHENKEVELD A. J. 
Published: May 2006

SummaryThe life‐histories of Carlina vulgaris L., Daucus carota L., Euphrasia officinalis L., Gentianella germanica (Willd). Börner, Linum catharticum L., and Scabiosa columbaria L. in a chalk grassland in the Netherlands are described on the basis of frequent observations during a period of three and a half years. E. officinalis and a small part of the L. catharticum population were found to be annual. G. germanica and the major part of the L. catharticum population were biennial, whereas the other species took several years to reach maturity. All species except the major part of the Scabiosa columbaria population were monocarpic.Vegetation cover influenced the occurrence of short‐lived forbs, but a large variation is found in the data. In D. carota, E. officinalis and Scabiosa columbaria seed production had a marked effect on seedling density in the following year.Shoot growth in Scabiosa columbaria seedlings varied at various vegetation densities. Furthermore, a marked correlation was found between rosette size and the probability of becoming mature in the subsequent year.Within one grassland, life‐history types within the group of short‐lived species are found to vary. On the one hand, there are the small‐seeded annuals with high mortality, but rather constant density of mature plants (Euphrasia), and on the other hand there are the more conservative life histories (Carlina, Daucus and Scabiosa), with larger seeds, lower mortality rates, but higher age of first reproduction and considerable variation in the density' of individuals.
ON THE ECOLOGY OF SHORT‐LIVED FORBS IN CHALK GRASSLANDS: SEMELPARITY AND SEED OUTPUT OF SOME SPECIES IN RELATION TO VARIOUS LEVELS OF NUTRIENT SUPPLY
Authors: VERKAAR H. J. , SCHENKEVELD A. J. 
Published: May 2006

SummaryAn experiment was set up in order to investigate semelparity and seed output of Daucus carota L., Linum catharticum L., Picris hieracioides L. and Scabiosa columbaria L. in relation to various levels of nutrient supply.Some plants of Daucus carota and Scabiosa columbaria were found to flower within one growing season, when nutrient supply was at its highest, whereas the other species did not flower. In the second growing season almost all plants receiving a maximum supply of nutrients flowered and produced seeds. In Linum catharticum flowering plants were recorded in all treatments.The reproductive plants of all species died after seed shedding, except those of Picris hieracioides and Scabiosa columbaria under high nutrient conditions which formed lateral shoots. These plants survived and were iteroparous.Seeds produced early in the fruiting period were most numerous and heaviest in the treatments with highest levels of fertilization. In Daucus and Scabiosa a positive linear relationship between seed weight and germination success was found. Thus, the plants grown under the highest nutrient supply conditions showed the highest seed output in all species, although this was less clear m Linum. The significance of these results for the field situation is discussed.
POLLEN MORPHOLOGY OF THE GENUS SILENE L. (CARYOPHYLLACEAE), SECTIONS SIPHONOMORPHA OTTH AND AURICULATAE (BOISS.) SCHISCHK.
Authors: GHAZANFAR SHAHINA A. 
Published: May 2006

SummaryPollen morphology of the species of Silene of the Sections Siphonomorpha and Auriculatae is described. Species belonging to Section Siphonomorpha show only punctate tubuliferous/spinulose ektexine while species belonging to Section Auriculatae show punctate, reticulate and semi‐reticulate tubuliferous/spinulose ektexine. The study suggests the derivation of reticulate ektexine from punctate ektexine and the association of reticulate ektexines with sporophytically advanced taxa. It also emphasizes the retention of the Caryophyllaceae in the Centrospermae.
ANTHROPOGENIC CHANGES FROM NEOLITHIC THROUGH MEDIEVAL TIMES
Authors: DIMBLEBY G. W. 
Published: May 2006

SummaryThe long period covered by this paper probably saw the most drastic changes wrought by man on the plant cover of these islands in the whole of postglacial history. Much of our information about vegetation changes comes from those parts of the country where peats and mires are abundant, which leaves those areas which were the cradle of successive cultural groups largely unrepresented. Sources of environmental evidence are now emerging even from this unpromising background, an important element amongst which are man's own works. The evidence of changes wrought by man may come from non‐botanical as well as botanical material. Pollen, charcoal, phytoliths, seeds, mosses, and other macroscopic plant remains may be extracted, but indirect evidence may also be obtained from land snails, insects, bones (including small vertebrates), as well as from preserved soils and land surfaces.In the various environments considered a trend from forest through clearance to pastoral or arable agriculture can usually be demonstrated. These changes may ultimately result in site deterioration on a large scale, the nature of which will depend upon the ecological conditions and the practices at work. In extreme cases peat may form or soil erosion take place. On base‐poor soils, soil acidification may become so intense that the land is no longer usable for traditional agriculture and is allowed to degenerate to moorland or heath. In early historic times much degraded land came into use again for hill‐grazing, a process which further depauperated both the flora and the soils.
THE FLORA AND VEGETATION OF BRITAIN: ECOLOGY AND CONSERVATION
Authors: PIGOTT C.D. 
Published: May 2006

SummaryA main aim of studies of the British flora in future must be ecological, with plant ecology developed as a multidisciplinary and experimental science which has as its primary purpose the understanding of vegetation. The response of species to environment is largely mediated through the response of vegetation. It is essential to have an accepted and widely understood classification of British vegetation.Destruction of the more natural types of vegetation, with accompanying loss of species, should be a matter of national concern as many communities are irreplaceable. Their loss represents irreversible damage to our cultural heritage and a deterioration of the quality of our environment. Ecological understanding of vegetation is necessary to ensure that conservation achieves its primary purpose.
THE INFLUENCE OF DRY STORAGE TEMPERATURE ON THE RESPONSE OF BROMUS STERILIS L. SEEDS TO LIGHT
Authors: HILTON JANET R. 
Published: May 2006

SummaryThe response of two populations of Bromus sterilis L. seed to light at 15°C was studied over 12 months when seeds were stored at different temperatures. White and red light inhibited the germination of both collections of seed, inhibition persisting for longer periods at low (4°C) than at high (23 °C) temperatures. The two populations of seed behaved similarly in their response to all light treatments.
ON THE DEVELOPMENT OF OSTEOSCLEREIDS IN SEED COATS OF PISUM SATIVUM L.
Authors: HARRIS W. M. 
Published: May 2006

SummaryThe development of osteosclereids during seed‐coat maturation in Pisum sativum was observed by light and electron microscopy. Osteosclereid precursors are small, densely staining cells which elongate and mature after the macrosclereids. The lateral cell walls in the region of the cell equator become heavily thickened preventing further expansion, while the ends of the cells retain their thin walls and continue to expand. This growth creates the bone‐shaped cell typical of osteosclereids. The cells become separated from each other by accelerated circumferential expansion of the cell layers above and below them and by cell layers. Cell wall synthesis in osteosclereids involves coated and smooth vesicles from the Golgi, and vesicles with fibrillar contents from the endoplasmic reticulum.
EFFECTS OF SOIL TRENCHING AND CORING ON THE FORMATION OF ECTOMYCORRHIZAS ON BIRCH SEEDLINGS GROWN AROUND MATURE TREES
Authors: FLEMING L. V. 
Published: May 2006

SummaryInitially non‐mycorrhizal seedlings of birch (Betula pendula Roth.) were grown for a season around two 11‐year‐old birch trees on an experimental site south of Edinburgh. Some seedlings (non‐isolated) were planted in undisturbed positions, others (trenched) in volumes of soil isolated from the mature tree by trenches, and yet others (cored) in cores of soil (8 × 10 cm diameter) that had been removed and replaced immediately.Mycorrhizas of Lactarius pubescens (Fr. ex Krombh.) Fr., Lactarius glyciosmus (Fr. ex Fr.) Fr., and Leccinum scabrum (Bull. ex Fr.) S. F. Gray and Leccinum roseofracta Watl. developed abundantly on the non‐isolated seedlings but usually very poorly on the trenched and cored seedlings. That some development of Leccinum mycorrhizas occurred in trenched areas is attributed to incomplete severance of roots. In contrast, mycorrhizas of other fungi, for example Hebeloma spp. and Inocybe spp., developed most abundantly on trenched and cored seedlings rather than on non‐isolated seedlings.The results demonstrate an important difference between types of ectomycorrhizal fungus. Lactarius and Leccinum spp. seem to depend on a continuing supply of photosynthate from a mature tree in order to colonize seedling roots, whereas several other mycorrhizal fungi show no such dependence. The results also indicate an important role for mycelial strands in establishment of mycorrhizas by some fungi (Lactarius pubescens and Leccinum spp.) and thus parallel previous reports on the importance of mycelial strands in colonization of substrata by saprophytic and pathogenic fungi.
STUDIES ON METAL UPTAKE BY PLANTS FROM SERPENTINE AND NON‐SERPENTINE POPULATIONS OFTHLASPI GOESINGENSEHÁLÁCSY (CRYCUFERAE)
Authors: And R. D. REEVES , BAKER A. J. M. 
Published: May 2006

SummaryPlants of a serpentine (S) and a calcareous (C) population‐type ofThlaspi goesingenseHálácsy were raised from seed in various serpentine and artificial limestone soils with and without Zn amendment. S‐ and C‐plants grown on metal‐enriched substrates accumulated similar, extremely high concentrations of Ni, Zn, Co and Mn in the above‐ground dry matter; they also showed a marked reduction of Ca uptake, which was combined with increased Mg uptake, in all the serpentine treatments. The fate of the Ni stored in seeds was followed when S‐plants were grown in normal soil. Nickel was conserved and merely diluted within the plant dry matter as growth proceeded. Seedlings transplanted from serpentine soil to non‐nickeliferous soil showed similar dilution effects, suggesting little or no overall Ni loss from the plant. The similar metal‐uptake characteristics and performance of plants from the two populations studied suggests a constitutional metal tolerance within the species and the existence of a non‐specific metal detoxification system.
SENESCENCE AND POST‐MORTEM CHANGES IN THE ULTRASTRUCTURE OF SPHAGNUM FUSCUM (KLINGGR.) SCHLEICH LEAF CELLS
Authors: KARUNEN PIRJO , KÄLVIÄINEN EEVA 
Published: May 2006

SummarySphagnum fuscum (Klinggr.) Schleich leaves collected from various depths down to 40 cm from the surface were examined by light and electron microscopy and for their capacity to regenerate. Leaf cells never produced new plants: all regeneration in the subsurface samples was from small groups of cells on branches near the junction with the main stems.Non‐hyaline leaf cells produced in the early summer are senescent by the autumn and dead within a year. Although all the organelles disintegrate these cells invariably contain large lipid globules even to a depth of 30 cm. Fungal hyphae were often found in the non‐hyaline leaf cells from all depths and were frequently associated with eroded lipid bodies. The hyphae spread from cell to cell through the end walls between adjacent non‐hyaline leaf cells at the sites of plasmodesmata. Lipids may be the major catabolite for the fungi within old shoots of Sphagnum.
QUANTITATIVE MICROANALYSIS OF MN, ZN AND OTHER ELEMENTS IN MATURE WHEAT SEED
Authors: MAZZOLINI A. P. , PALLAGHY C. K. , LEGGE G. J. F. 
Published: May 2006

SummaryA scanning proton microprobe has been used to determine quantitatively the distribution of Mn, Zn and other elements in the mature wheat seed (Triticum aestivum cv. Gamenya). Both X‐ray and nuclear scattered proton data were collected during the irradiation of a 40 μm‐thick longitudinal section, and these were used to calculate absolute elemental concentrations for the various features of interest in the embryo region. Elemental maps were collected for a number of transverse and longitudinal sections (obtained from several seeds), but comprehensive analytical information was collected from one typical longitudinal section only. In the embryo, the concentration (by dry weight) of Mn was highest in the radicle (1400 ± 200 μg g−1 error is 1 SD) and lowest in the coleorhiza (200 ± 30 μg g−1), whereas Zn was highest in the scutellum (600 ± 100 μg g−1 and lowest in the leaf primordium (410 ± 70μg g−1). Comparisons with direct bulk chemical analysis of excised embryos showed agreement. The possible biological significance of the distribution of elements is discussed. An extensive appendix allows botanists to properly assess the techniques used.
DIEL PATTERNS OF CARBOHYDRATE METABOLISM IN LEAF BLADES AND LEAF SHEATHS OFPOA ANNUAL. ANDPOA×JEMTLANDICA(ALMQ.) RICHT.
Authors: BORLAND A. M. , FARRAR J. F. 
Published: May 2006

SummaryA study was made of diel changes in carbohydrate content, net gas exchange and export from leaf blades and leaf sheaths inPoa annuaL. (a ruderal) andPoa×jemtlandica(Almq.) Richt. (a sub‐arctic grass). Sucrose was the most abundant form of carbohydrate in the leaf blades with lesser amounts of starch and fructans also present. The proportions of fixed carbon allocated to export, storage and respiration in leaf blades were similar, and carbohydrates showed broadly similar patterns of diel fluctuation, in both species. However, the relative rates of sucrose and starch accumulation and depletion and the diel patterns of export in the leaf blades were different in the two species. Starch was the predominant form of carbohydrate in the sheath, with soluble sugars and fructans also present. Starch and soluble sugars showed diel accumulation and depletion in the sheathsof Poa annuabut not inPoa×jemtlandica.The effects of extended darkness suggest that factors controlling carbohydrate metabolism in the sheath may be different to those operating in the leaf blade. The large fluxes of carbohydrate through the sheath suggest that it serves mainly as a thoroughfare for carbohydrates.
TRANSFER CELLS AND HARTIG NET IN THE ROOT EPIDERMIS OF THE SHEATHING MYCORRHIZA OF PISONIA GRANDIS R. BR. FROM SEYCHELLES
Authors: ASHFORD A. E. , ALLAWAY W. G. 
Published: May 2006

Summary Pisonia mycorrhizas found in Seychelles possessed transfer cells next to the fungal sheath and Hartig net. There were extensive wall‐ingrowths on outer‐tangential and radial walls of epidermal cells, and on parts of cortical cells, in contact with the mycorrhizal fungus. In general structure, having basidiomycete sheath, transfer cells, and Hartig net between epidermal cells only, the mycorrhizas resembled those from the Australian Great Barrier Reef; Seychelles material had poorer definition of the layers in the sheath and a better‐developed Hartig net. Mycorrhizal development was best at sites with coral sand, the characteristic habitat for P. grandis. At the one site which had soil derived from granite, only one mycorrhiza was found, although many roots were examined and most of these had hyphae at the root surface. In the older mycorrhizas the transfer‐cell walls changed from red‐purple staining to blue with toluidine blue (pH 4‐4), probably because of incorporation of phenolic material; the sheath showed damage and increased impregnation with dark‐coloured phenolic material. From these changes it is suggested that the mycorrhizal association is likely to be functional for only a short distance back from the tip. Comparison of mycorrhizal and non‐mycorrhizal roots suggested that the transfer cells were induced by the fungus, but that a complete sheath was not necessary for their formation. The transfer‐cell wall‐ingrowths were clearly distinguishable from ‘papillae’ formed in fungal invasion, by their morphology, staining properties, and appearance in the electron microscope. The unique structure of the Pisonia mycorrhiza puts it in a category of its own, and its discovery in Seychelles implies that the mycorrhizal habit is widespread in this species.
GERMINATION IN POPULATIONS OF SOLANUM DULCAMARA L. FROM CONTRASTING HABITATS
Authors: PEGTEL D. M. 
Published: May 2006

Summary Solanum dulcamara L. grows in widely contrasting habitats, from waterlogged and shaded to relatively dry and fully exposed sites. Representative seed samples from a number of populations were collected. Germination was studied under a variety of experimental conditions in order to determine whether populations from different habitats were genetically differentiated. Under the conditions employed in these experiments it was concluded that populations probably did not differ genetically in their germination responses.
EFFECT OF IRRADIANCE AND LIGHT QUALITY ON STARCH SYNTHESIS BY ISOLATED CHLOROPLASTS OF CODIUM FRAGILE
Authors: WILLIAMS MICHAEL L. , COBB A. H. 
Published: May 2006

SummaryNet starch synthesis by isolated chloroplasts of the intertidal alga Codium fragile (Suringar) Hariot was determined by enzymic hydrolysis (amyloglucosidase/α‐amylase) of solubilized chloroplast samples followed by the measurement of the resultant glucose yields by hexokinase/glucose‐6‐phosphate dehydrogenase‐coupled reactions.Net starch synthesis was only observed between 100 and 375 μmol m−2 s−1 (PAR) corresponding to irradiance values which supported saturating or super‐saturating rates of photosynthesis. Light filter inactivation of the light‐harvesting complex carotenoids siphonoxanthin and siphonein reduced net starch synthesis by 68 %. These findings are discussed in relation to photosynthesis in an intertidal zone environment.
FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS
Authors: COATES D. , RAYNER A. D. M. 
Published: May 2006

SummaryThe spatial development, in beech logs exposed to air‐borne and soil‐borne inoculum, of mature fungal communities containing mutually or unilaterally exclusive mycelia of decay species is described and related to the ecological strategies and interaction of participant individuals. A combative heirarchy is recognized between (i) ruderal and/or stress‐tolerant individuals which are spatially dominant early on and then decline, through (ii) air‐borne combative individuals of decay fungi, such as Coriolus versicolor (L. ex Fr.) Quél. and Stereum hirsutum (Willd. ex Fr.) S. F. Gray, which establish mutually exclusive decay columns expanding away from the aerial cut surface, and culminating with (iii) highly combative individuals of mycelial cord‐formers such as Phallus impudicus (L.) Pers. and Phanerochaete velutina (DC ex Pers.) Parmasto, which invade slowly from the base, ultimately occuping large volumes of wood, causing intense decay, and replacing many of the pioneers.Addition of basidiospore suspensions of Bjerkandera adusta (Willd. ex Fr.) Karst., C, versicolor, Hypholoma fasciculare (Huds. ex Fr.) Kummer or S. hirsutum to the aerial cut surface appeared to affect community dynamics and functioning markedly. Development of decay columns by air‐borne fungi was inhibited and associated with enhanced vertical penetration by basally‐colonizing fungi, and persistence of the relatively non‐combative species Xylaria hypoxylon (L. ex Hooker) Greville and Armillaria bulbosa. (Barla) Kile & Watling. Re‐cutting of the aerial cut surface resulted in community development patterns somewhat intermediate between those in naturally colonized and inoculated logs.
IRON‐INDUCED OXYGEN RADICAL METABOLISM IN WATERLOGGED PLANTS
Authors: HENDRY GEORGE A. F. , BROCKLEBANK K. JANE 
Published: May 2006

SummaryRoots of the iron‐sensitive wetland plant, Epilobium hirsutum L., respond to oxygen‐depletion by enhanced uptake of ferrous ions. Evidence is presented for an iron‐catalyzed reaction within roots leading to super oxide radical formation and the induction of superoxide dismutase. The immediate product, H2O2, appears to accumulate in the absence of catalase and low activity of root peroxidases, resulting in hydroxyl radical formation, inhibition of protein synthesis, increased lipid peroxidation and gross cellular damage. Evidence for alternative ‘healthy’ responses is given. A scheme is presented which outlines a biochemical mechanism for iron‐mediated flood or waterlogging tolerance and intolerance in plants.
THE INFLUENCE OF IRRADIANCE ON ROOT REGENERATION IN STEM CUTTINGS OF MUNG BEAN
Authors: JARVIS B. C. , ALI A. H. N. 
Published: May 2006

SummaryCuttings from stock plants grown under continuous irradiance need a supply of borate for roots to develop. This requirement is alleviated, at least in part, by subsequent exposure of stock plants to periods of continuous darkness. Nevertheless, rooting capacity, as shown by responsiveness to supplied IBA, is enhanced by irradiating stock plants. Exposure of the region of regeneration to irradiance diminishes root formation, but exposure of the rest of the cutting enhances it in response to IBA. This effect is mediated via the leaves. In the absence of supplied auxin, irradiance of the leaves only enhances rooting when the hypocotyl is shaded.