bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHLOROPLAST STRUCTURE IN COILED AND UNCOILING CROZIERS OF PILULARIA GLOBULIFERA
Authors: WHATLEY JEAN M. 
Published: May 2006

SUMMARYThe sequence of development of chloroplasts in coiled and newly uncoiled croziers of Pilularia globulifera L. is described. Changes in chloroplast shape and lamellar orientation could be correlated with particular states of crozier coiling or unfolding.
NITROGEN FIXATION IN THE ROOT NODULES OF VICIA FABA L. IN RELATION TO THE ASSIMILATION OF CARBON. II. THE DARK FIXATION OF CARBON DIOXIDE
Authors: LAWRIE ANN C. , WHEELER C. T. 
Published: May 2006

SUMMARYHigh activity of phosphoenolypyruvate carboxylase, malate dehydrogenase and malic enzyme has been found in extracts from broad bean nodules. Tracer studies of the metabolism of 14CO2 fixed by detached nodules showed that the amino acid fraction sequestered most radioactivity and that no radioactivity was associated with glucose and fructose, the main free sugars in ethanolic extracts of the nodules. The pattern of labelling supports an important role for glutamate, aspartate and asparagine in the metabolism of the fixed carbon, but relatively little radioactivity was associated with glutamine. Most of the radioactivity in the acidic fraction of the nodules was in malic and itaconic acids. Although the latter was not detected immediately on detachment of the nodules, it was present in amounts equal to malic acid 30 min after detachment.
POLYPHOSPHATE IN EUCALYPT MYCORRHIZAS: A CYTOCHEMICAL DEMONSTRATION
Authors: ASHFORD A. E. , LEE M. LING , CHILVERS G. A. 
Published: May 2006

SUMMARYSmall, more or less spherical metachromatic granules have been detected within the Hartig net and inner sheath hyphae of Eucalyptus fastigata mycorrhizas, and shown by various cytochemical tests to contain polyphosphates. These granules are believed to be the cytological equivalent of the biochemically characterized phosphate storage pool which other workers have defined on the basis of radiotracer studies.
THE EFFECT OF MYCORRHIZAL INFECTION OF PINUS SYLVESTRIS AND PICE A ABIES BY TWO BOLETUS SPECIES ON THE ACCUMULATION OF PHOSPHORUS
Authors: MEJSTŘÍK V. K. 
Published: May 2006

SUMMARYSeedlings of Pinus sylvestris and Picea abies in sterile forestsoil or in a mixture of vermiculite and peat were inoculated with Boletus luteus, B. bovinus, both species, non‐sterile forest soil or non‐sterile soil plus B. bovinus. Following mycorrhizal development, the increase of the dry weight of roots and shoots over controls was highly significant in all combinations. The phosphorus content in mycorrhizal seedlings was higher than in nonmycorrhizal controls but only small differences were noted between different combinations. B. luteus was the better symbiont for uptake of phosphorus by Pinus sylvestris and Boletus bovinus for Picea abies.
LATERAL ROOT ELONGATION IN VICIA FABA L: THE PLANES OF CELL DIVISION IN THE EPIDERMIS, CORTEX AND STELE
Authors: MacLEOD R. D. , McLACHLAN S. M. 
Published: May 2006

SUMMARYPlanes of cell division have been investigated in the epidermis, cortex and stele, 400–1000 μm behind the cap apex, in lateral roots of Vicia faba, as they lengthened from just emerged to 4 cm. The frequency with which cells divided in any one plane differed in the various root tissues. Also, changes took place in the frequency with which the spindle was oriented in a radial, tangential or longitudinal plane in each tissue basally along these roots and as the laterals elongated. The contributions of cell division and cell expansion to increase in the dimensions of each tissue are discussed.
NITROGEN METABOLISM IN LICHENS
Authors: HITCH C. J. B. , MILLBANK J. W. 
Published: May 2006

SUMMARYThe blue‐green algal population and heterocyst frequency in Peltigera aphthosa, P. canina and P. polydactyla have been estimated by means of a chromium trioxide maceration technique followed by visual and photographic observation. Populations of the order of 107 cells/sq cm thallus in P. canina and P. polydactyla, and 106/sq cm in P. aphthosa have been found. These figures are some threefold greater than previously reported; the earlier results are explained by unexpectedly high fragility of the algal cells.A heterocyst frequency of c. 3.5% in P. canina confirms previous estimates obtained by another technique; P. polydactyla is similar but P. aphthosa has a very high heterocyst frequency, c. 22% of the total cells. These findings are reflected in the nitrogenase activity and support the concept that the enzyme is only active in heterocysts.
KINETIC STUDIES ON THE BINDING OF ZINC IONS BY THE LICHEN USNEA FLORIDA (L.) WEB.
Authors: WAINWRIGHT S. J. , BECKETT P. J. 
Published: May 2006

SUMMARYIt is shown that the binding of zinc by Usnea florida is reversible and follows a classical Langmuir adsorption isotherm. Zinc binding is dependent on pH and this can be explained as competitive inhibition of zinc binding by protons.
POPULATION GROWTH IN CLADONIA STELLARIS (OPIZ.) POUZ. AND VEZDA
Authors: YARRANTON G. A. 
Published: May 2006

SUMMARYPopulations of Cladonia stellaris in burnt areas of the northern Ontario clay belt were observed photographically from 1968 to 1974. Population growth is logistic with a typical convergent standing crop of 500 g per m2, reached about 30 years after establishment. There is considerable oscillation about the convergent standing crops with time, as well as environmentally determined variations between crops at different sites. Rates of growth are strongly correlated with successional maturity, so that time of establishment may influence the subsequent population size. Final carrying capacity is apparently determined by a complex of factors effective through their influence on light and water availability and by direct physical interference of other species. Ericaceous shrubs and Pleurozium schreberi seem to be the most influential. Cladonia stellaris does not appear until 25 years after fire, but rapidly becomes the most abundant lichen by means of clonal growth. Clones develop by three kinds of budding and subsequently undergo fusion and fission as growth proceeds. Longer range dispersal is by means of small thallus fragments and is evidently highly efficient as newly colonized areas exhibit widespread potential distributions.
THE BIOLOGY OF MYCORRHIZA IN THE ERICACEAE V. THE EFFECTS OF MYCORRHIZAL INFECTION, SOIL TYPE AND PARTIAL SOIL‐STERILIZATION (BY GAMMA‐IRRADIATION) ON GROWTH OF CRANBERRY (VACCINIUM MACROCARPON AIT.)
Authors: STRIBLEY D. P. , READ D. J. , HUNT R. 
Published: May 2006

SUMMARY Vaccinium macrocarpon was grown in open pots for 20 weeks on three heathland soils of decreasing fertility. Interactions between the effects of mycorrhizal infection, soil type and partial soil‐sterilization (by γ‐radiation) were studied by the calculation of various growth‐functions from fitted curves.Mycorrhizal infection increased whole‐plant dry weight and relative growth‐rate but decreased the root/shoot ratio of plants grown on two of the irradiated soils. These plants contained a greater percentage of nitrogen and had higher specific absorption rates for N than uninfected controls.The fertility of each soil was increased by partial sterilization. On one irradiated soil, mycorrhizal infection was without effect: all plants grew rapidly and had large specific absorption rates which were associated with a large net mineralization of NH4+‐N.Changes in the values of growth‐functions with time occurred in most treatments and were especially marked in plants grown on the irradiated soil with marked mineralization of NH4+‐N. The importance of these ontogenetic variations is considered in relation to other experiments on the response of higher plants to mycorrhizal infection.
TYPES OF VERNATION IN THE CYATHIA OF EUPHORBIA MILLI DES MOULINS
Authors: BAHADUR BIR , REDDY N. PRATAP 
Published: May 2006

SUMMARYFour types of vernation in the cyathia are described. The cyathium is subtended at the base by two bracts whose vernation may twist to the left or to the right or it may be neutral; two neutral types are possible. Counts made on sixteen different plants from various localities show that left and right‐handed cyathia occur with equal frequency but that neutral cyathia are less common. The different types of cyathia appear to occur at random in the umbels in which they are grouped.
CYTOGENETIC STUDIES IN THE GENUS POTENTILLA L.
Authors: GOSWAMI D. ACHARYA , MATFIELD B. 
Published: May 2006

SUMMARYCytogenetic studies involving eighteen species of Potentilla of the section Gymnocarpae were made to investigate their phylogenetic relationships and to see whether any correlation exists between morphology and crossing relationships.The chromosome numbers of Potentilla ambigens Greene (2n = 82) and P. montenegrina Pant, (2n = 28) were determined for the first time. New intraspecific chromosome races were observed in three species: P. pennsylvanica L. (2n = 42), P. astrisanguinea Lodd. (2n = 84) and P. grandiflora L. (2n = 42).Hybrids were obtained from only four of 628 crosses in 111 different combinations (P. nepalensis Hook, ×P. montenegrina Pant., P. astrisanguinea Lodd. ×P. ambigens Greene, P. recta L. × P. cf. hirta L. and P. grandiflora L. ×P. crantzii (Crantz) Beck.). The position of the crossing barrier in the unsuccessful crosses varied. Sometimes the pollen failed to germinate but in other cases well‐developed pollen tubes were observed. No definite correlation was found between the morphological similarity of species and their crossing ability.Meiotic studies on the hybrids indicated some chromosomal homologies between the genomes of P. recta and P. cf. hirta and between P. grandiflora and P. crantzii, but not between P. nepalensis and P. montenegrina.
POLLEN FLOW IN LYTHRUM JUNCEUM, A TRISTYLOUS SPECIES
Authors: ORNDUFF ROBERT 
Published: May 2006

SUMMARYStudies of the pollen loads present on stigmas of flowers of the self‐incompatible tristylous Lythrum junceum in Morocco indicate that the position of the stigma has an important effect on the proportion of pollen from long‐level anthers that is deposited on the stigmas. The greatest amount of large pollen from the longest set of stamens is found on stigmas of long‐styled flowers. Because of the inability to discriminate between small pollen grains from mid‐level anthers and those from short‐level anthers it is not clear how stigma position may influence the distribution of these small pollen grains. In the Moroccan population studied, plants with long‐, mid‐, and short‐styled flowers are present in a 1:1:1 ratio. The chief pollinator during the period of study was the honey bee, Apis mellifera, which preferentially removes large pollen grains from flowers. Longs and Mids produce approximately equal numbers of pollen grains per flower, and Shorts produce c. 77% of the pollen of each of these two forms. Acetolysis of stigmas provides more accurate estimates of stigmatic pollen loads than does microscopic examination of intact stigmas, although the proportional representation of the two size classes of pollen is similar with either method. This study represents the first published analysis of pollen flow in a tristylous species within its native range and suggests that tristyly serves to promote compatible pollinations, thus supporting the classical interpretation of the biological significance of tristyly.
EFFECTS OF CCCP ON PHOTOSYNTHESIS AND ON ACTIVE AND PASSIVE CHLORIDE TRANSPORT AT THE PLASMALEMMA OF HYDRODICTYON AFRICANUM
Authors: RAVEN J. A. , GLIDEWELL S. M. 
Published: May 2006

SUMMARYCCCP inhibits photosynthetic CO2 fixation more than photosynthetic O2 evolution in Hydrodictyon africanum, while the photosystem two inhibitor, DCMU, inhibits the two processes equally. These results are consistent with CCCP acting as an uncoupler of photophosphorylation, thereby inhibiting CO2 fixation, and the remaining O2 evolution being associated with the ATP‐independent reduction of some (unknown) electron acceptor. Analysis of tracer chloride fluxes at the plasmalemma into active influx, exchange diffusion and passive uniport components supports previous conclusions, based on the assumption that all the tracer influx was due to active transport, that active chloride influx is relatively ATP‐independent. Some problems inherent in the occurrence of redox‐coupled active transport at the plasmalemma of eukaryotes are discussed, and a scheme which accounts for active chloride transport at the plasmalemma of H. africanum is proposed.
THE UPTAKE OF COPPER AND ITS EFFECT UPON RESPIRATORY PROCESSES OF ROOTS OF COPPER‐TOLERANT AND NON‐Tolerant CLONES OF AGROSTIS STOLONIFERA
Authors: WU L. , THURMAN D. A. , BRADSHAW A. D. 
Published: May 2006

SUMMARYThe uptake of copper by non‐tolerant and tolerant clones of Agrostis stolonifera has been studied. In both clones the roots accumulated more copper than the leaves and the roots of the tolerant clone accumulated more copper than the non–tolerant one. When supplied at concentrations above 10 μM in culture solutions copper moved up into the leaves of the non‐tolerant clone more readily than the tolerant one. Uptake of oxygen by roots was only affected when they were pretreated with copper, the non‐tolerant ones being more sensitive to inhibition than tolerant ones. Over the concentration range tested copper had no effect upon l‐malate‐dehydrogenase (MDH) activity in root extracts of either clone. Extracts prepared from non–tolerant roots pretreated with copper were found to contain less MDH activity than those prepared from tolerant ones. It is suggested that this was due to an inhibition of protein synthesis in the roots of the non‐tolerant clone, which did not occur in the tolerant one.
NITROGEN METABOLISM IN LICHENS
Authors: HITCH C. J. B. , MILLBANK J. W. 
Published: May 2006

SUMMARYThe N2(C2H2) fixing activity was surveyed in lichens of diverse structure and habitat, all containing a blue‐green phycobiont; twenty‐six species from fourteen genera are reported for the first time to fix nitrogen. Rates of N2(C2H2) fixation showed great variability between different lichen samples.The proportion of heterocysts, as the assumed site of N2 fixation, was estimated in all the above lichens together with fourteen additional species. In lichens with one phycobiont, heterocysts form about 4% of the total algal cell population; in those with two phycobionts the blue‐green member is found in special structures and has a very high proportion of heterocysts, typically 20–30%; the N2(C2H2) activity appears to reflect this. The high proportion may be associated with the proximity of the green phycobiont.
EXPERIMENTAL ECOLOGICAL GENETICS IN PLANTAGO
Authors: WU LIN , ANTONOVICS JANIS 
Published: May 2006

SUMMARYInduction of roots and shoots from leaves of Plantago lanceolata L. using IAA is a very effective technique which could be extended to large scale cloning for vegetative propagation and assay procedures in genecological studies on this and other species. In P. lanceolata, there were no differences between populations from contrasting habitats with regard to proportion of leaves producing roots and shoots. There was a high correlation between zinc tolerance measured on rooted leaves and on equivalent rooted tillers.
THE EVOLUTION OF MORPHOLOGICAL NOVELTY EXEMPLIFIED IN THE GROWTH PATTERNS OF SOME GESNERIACEAE
Authors: JONG KWITON , BURTT B. L. 
Published: May 2006

SUMMARYThe growth pattern of certain South African species ofStreptocarpussub‐genusStreptocarpushas been investigated, using in particular the speciesS. fanniniae.It is shown that the vegetative plant body consists of repetitive units, the first being formed by the accrescent cotyledon. These units are here called phyllomorphs: each has a stalk (the petiolode) showing a mixture of axis‐like and petiole‐like features, and a lamina. The development of the phyllomorph is largely controlled by a triad of meristems situated near junction of petiolode and lamina. The basal meristem provides new growth at the base of the lamina; the petiolode‐meristem contributes to the growth of the midrib as the lamina enlarges and to elongation of the petiolode; the groove‐meristem initiates the growth of new phyllomorphs and of the inflorescences.Recognition of the phyllomorph as a repetitive structural unit permits satisfactory description and comparison of anomalous growth patterns of various species ofStreptocarpusand of certain other genera of Old World Gesneriaceae. Its evolution and diversification is briefly discussed.
THE HILL VEGETATION OF NORTH HOY, ORKNEY
Authors: PRENTICE H. C. , PRENTICE I. C. 
Published: May 2006

SUMMARYNorth Hoy is an area containing a remarkable diversity of vegetation in a small area. A phytosociological account of the hill vegetation of North Hoy is presented, making use of an ordination method to clarify the inter‐relationships of the moorland vegetation types, as well as traditional methods. It has proved very interesting to compare the vegetation with the account of Scottish Highland vegetation by McVean and Ratcliffe (1962). Birks' (1973) account of the vegetation of Skye has also been drawn on, particularly as a source for a system of classes, orders and alliances applicable to Scottish vegetation. The environmental background (climate, topography, geology, patterned ground phenomena, animal populations and past and present land‐use) is summarized.Several important general features of the vegetation of North Hoy deserve emphasis, especially from a conservation point of view.

Many good examples of noda characteristic of strongly basic soils, especially mires and grasslands, are found. Some of these have a rather restricted distribution in Scotland.
Small areas of woodland, including one very species‐rich wood, are found in sheltered ravines. These are well‐developed and regenerating, and represent the northernmost occurrence of woodland in Britain.
Many species and many types of vegetation occur at unusually low altitudes (as is also observed in northernmost Sutherland, Caithness and Shetland). Particularly interesting are certain montane dwarf heaths, which are associated with well‐developed patterned ground features.
The area contains both occurrences of ‘Atlantic’ bryophytes and well–developed stands of lichen heath and lichen‐rich bog, which have a strongly ‘continental’ distribution in Scotland. This apparent paradox is discussed but not resolved.
The low level of sheep‐grazing and absence of burning in recent years have led to some unusual vegetation features.

Phytosociological tables are presented in an appendix. A second appendix lists the lichens collected, as identified by P. W. James, with a short note on the occurrence of each.
POLLEN DIAGRAMS FROM THE SHETLAND AND FAROE ISLANDS
Authors: JÓHANSEN JÓHANNES 
Published: May 2006

SUMMARYTwo pollen diagrams are presented, one from Murraster, Shetland Mainland, and one from Hoydalar, Streymoy, Faroe Islands. Both localities are former lakes, now filled up, and in both places the sedimentation started about 10,000 years ago. In the Faroese diagram herbs are dominant throughout, while it can be seen that Juniperus and Salix have been of considerable significance and Betula nana has had a wide distribution in early Flandrian time. In the Shetland diagram large–leaved Betula and Corylus are also present, even though herbs were also dominant.
WIND‐BORNE SEED AND FRUIT MOVEMENT
Authors: BURROWS F. M. 
Published: May 2006

SUMMARYSeeds and fruits of widely differing sizes and shapes and which employ different flight styles in wind‐borne movement during dispersal are discussed qualitatively in general aerodynamic terms, and grouped according to aerodynamic rather than botanical features. Most of these groups are considered separately, though not in any great detail, and the salient features of the differing motions belonging to each are described. The response of species, in particular to variations in vertical wind velocities, is mentioned as an important factor affecting‐deposition and dispersal range, and how because of this response some forced deposition may be possible with the introduction of suitably shaped obstacles to wind flow.
CARBOHYDRATE METABOLISM AND DIFFERENTIATION IN SEEDLING ROOTS
Authors: FOWLER MICHAEL W. 
Published: May 2006

SUMMARYInformation relating to the changing activities of the Embden—Meyerhof—Parnas pathway, the pentose phosphate pathway and tricarboxylic acid cycle during the differentiation of roots is reviewed. Attention is particularly drawn to the operation in roots of a short series of reactions involving the enzymes phosphoenol pyruvate carboxylase, malate dehydrogenase and malic enzyme. The possible role of this pathway in the provision of NADPH for reductive biosynthesis is discussed.Sucrose is the major carbon source for carbohydrate metabolism in the root. Present information regarding its mode of entry into the root cells is sparse and confused. An attempt is made to pinpoint particular anomalies in the available data and to discuss some of the drawbacks associated with present approaches.Interactions between the different pathways of carbohydrate oxidation are extremely complex. Some attempts to define these have been made, with specific reference to the roles played in metabolism by the individual pathways. The presence of the pentose phosphate pathway dehydrogenases, the malic enzyme and isocitrate dehydrogenase in roots raises the question of the origin of NADPH for biosynthesis. There is some evidence to suggest a degree of association between specific reaction systems, based on ‘supply’ and ‘demand’ for NADPH.Very little information is available on the regulation of carbohydrate metabolism in roots. Some possible approaches to gaining more data on this important topic are outlined.
BIOCHEMICAL AND PHYSIOLOGICAL ASPECTS OF LEAF DEVELOPMENT IN COCOA (THEOBROMA CACAO)
Authors: BAKER N. R. , HARDWICK K. , JONES P. 
Published: May 2006

SUMMARYA quantitative study of the changes in chloroplast ultrastructure and carotenoids was made during cocoa flush leaf development. Plastid length, breadth, number of grana per plastid, index of lamellae per plastid and the number of lamellae per granum all increased with chlorophyll content. The number of chloroplasts per cell remained constant at three throughout leaf development. Lutein, neoxanthin, violaxanthin, α‐carotene and †‐carotene were the only carotenoids found in measureable amounts in cocoa leaves, and they all developed in parallel with chlorophyll. The phase of maximum chloroplast development in cocoa does not occur until after the termination of leaf expansion.
POLYPHOSPHATE GRANULES IN THREE DIFFERENT KINDS OF TREE MYCORRHIZA
Authors: LING‐LEE M. , CHILVERS G. A. , ASHFORD A. E. 
Published: May 2006

SUMMARYUsing cytochemical techniques, granules containing polyphosphate have been detected in Hartig net and sheath hyphae of Pinus ectomycorrhizas; in sheath, intercellular and intracellular hyphae of Arbutus ectendomycorrhizas; and in hyphae and vesicles of Liquidambar endo‐mycorrhizas.
PHOSPHATE UPTAKE ZONES OF MYCORRHIZAL AND NON‐MYCORRHIZAL ONIONS
Authors: RHODES L. H. , GERDEMANN J. W. 
Published: May 2006

SUMMARYMycorrhizal and non‐mycorrhizal onion seedlings were grown in individual soil chambers in which roots were confined to one side of a barrier. External hyphae of Glomus fasciculatus arising from mycorrhizal roots grew into an adjacent volume of soil. 32P was injected into soil at 1‐cm intervals up to a distance of 8 cm from the confined roots. Relatively high levels of radioactivity were subsequently detected in root segments of mycorrhizal plants at all distances from tracer injection. High levels of radioactivity were detected also in leaf segments of mycorrhizal plants. Radioactivity of root or leaf segments of non‐mycorrhizal plants did not exceed background level at any distance from tracer injection. 32P did not move more than 7.5 mm from the point of injection as indicated by gross autoradiography. Absorption of phosphate and its trans‐location to the host by hyphae of G. fasciculatus can extend the phosphate uptake zone of mycorrhizal onions to at least 7 cm from the root surface.