bluuebunny/crossref_metadata_2025 huggingface dataset:
Boron, strontium, and barium accumulation in selected plants and loss during leaf litter decomposition in areas influenced by coal strip mining
Authors: Lawrey James D.
Published: November 2007

In a 20-year-old abandoned surface coal mining area in eastern Ohio, concentrations of B, Sr, and Ba were determined for plant species commonly found in strip-mined and unstripped habitats. Where significant differences between elemental values of plants from strip-mined and unstripped habitats were observed, species from strip-mined areas exhibited higher values of B and lower values of Sr and Ba.Element loss during the 1st year of leaf litter decomposition was determined for leaves of 10 dominant tree species collected in the study area in late October 1975. Loss of boron was found to be greatest during the 1st year of leaf litter decomposition, followed by that of strontium. Some litter types exhibited accumulation of Ba during litter decomposition, whereas other types exhibited slight losses of Ba after 12 months.Leaching experiments using ovendried leaves and acidified distilled water to simulate rainfall revealed that boron was readily leached from all leaves studied except those of Fraxinus americana. A significant correlation was observed between amounts of B remaining after leaching and amounts remaining after 12 months of litter decomposition, which indicated that B loss during this interval was due to leaching losses. Strontium and barium exhibited little mobility as a result of leaching.Strip mining results in edaphic changes with concomitant increases in plant accumulation of boron. However, rapid losses of boron from decomposing leaf litter result in little accumulation of boron in litter with time.
Xylaria magnoliae sp.nov. and comments on several other fruit-inhabiting species
Authors: Rogers Jack D.
Published: November 2007

Xylaria magnoliae sp. nov. is described from fruits of Magnolia species from eastern United States. Xylaria magnoliae, formerly considered to be X. ianthino-velutina, is compared and contrasted with that species and with X. carpophila, X. culleniae, and X. persicaria.
Virulence dynamics in Puccinia graminis f.sp. avenae in Canada
Authors: Martens J. W. , McKenzie R. I. H.
Published: November 2007

Virulence in Puccinia graminis f.sp. avenue has been studied in Canada since 1921. Changes in host resistance, the succession of avirulence–virulence combinations, and changes in the composition of the pathogen population during the ensuing 57 years are presented graphically and indicate that the organism is highly dynamic even when the host population is relatively static. The early years are characterized by the presence of races virulent only on the universally susceptible host or cultivars with a single resistance gene followed by a gradual increase in virulence beginning in 1943 and a differentiation of eastern and western pathogen populations. By 1950 the zero- and one-gene virulence races were being displaced by Pg-1, -2 and Pg-1, -2, -3 virulence combinations in eastern Canada, an event that did not occur in the west until 1961. The latter period was characterized by the combining of virulence on all resistance genes except Pg-8 and Pg-13 in the east and Pg-9 and Pg-13 in the west. Virulence on resistance conferred by gene Pg-13 is still rare.
Needle microepiphytes in a Douglas fir canopy: biomass and distribution patterns
Authors: Carroll George C.
Published: November 2007

Distribution patterns and total cell-volume estimates for needle microepiphytes are presented for three strata in the canopy of a single old-growth Douglas fir tree. Microbial cell volume was estimated by photographing transverse sections of needles, tracing microbial profiles on Mylar film, cutting out the tracings, and determining the pooled trace weights from various zones of each needle section. Microbial cells are concentrated in the midrib groove and over the stomatal zones of individual needles. Microbial cell volume on the upper needle surfaces increases during the 1st year and declines in subsequent years. Cell volumes on the lower needle surfaces increase from the 1st to the 3rd year and decrease from the 3rd to the 4th year. An increase in microbial cell volume occurs on both upper and lower surfaces from year 7 to year 8. Total microbial cell volume in relation to available needle surface area is greatest in the lower canopy and decreases with increasing height in the canopy. The total volume of microbial cells on needles was estimated to be 1093 cm3 for the entire tree.
Effects of the intensity of audible sound on the growth and development of Rideau winter wheat
Authors: Weinberger Pearl , Measures Mary
Published: November 2007

Rideau wheat seeds and (or) seedlings exposed to 0.30, 1.25, 5.0, and 12.0 kHz sound frequencies and one display of random white noise at an intensity level of 92 dB grew normally, whereas some of those exposed to the same frequencies at 105–120 dB showed abnormalities and reduced weights of root and shoot tissue. Only sonication at 5 kHz and 92 dB led to stimulated tiller growth coupled with an increase in plant dry weight and number of roots. None of the sound treatments affected floral initiation and development.
Bryophytes of Banks Island, Northwest Territories, Canada
Authors: Steere William C. , Scotter George W.
Published: November 2007

Thirteen species of Hepaticae and 184 moss taxa are reported from Banks Island, Northwest Territories, Canada. Of these, 10 Hepaticae and 58 mosses are previously unreported from Banks Island. The list includes literature reports and recent collections.
Apical dominance in the rhizome of Agropyron repens: the influence of nitrogen and humidity on the translocation of 14C-labelled assimilates
Authors: Qureshi F. A. , McIntyre G. I.
Published: November 2007

When the buds on the rhizome of Agropyron repens were released from apical dominance either by increasing the nitrogen supply or by raising the humidity around the rhizome, their uptake of 14C-labelled assimilates from the parent shoot was significantly increased. While this effect was produced by each treatment when applied separately, the uptake of 14C by the buds was more than twice as great when both treatments were combined. The 14C level in the rhizome was also increased, this effect being greater and more consistent in response to the change in humidity than to the increased nitrogen supply. In the controls, uptake of the labelled assimilates was greatest by the bud at the apical node and decreased basipetally along the rhizome. This pattern was not correlated with bud size and probably resulted from a basipetal gradient of declining metabolic activity. Increasing the humidity around the rhizome altered this pattern, preferentially promoting the uptake of the label by the bud at the subapical node. To account for the stimulation of bud growth by high humidity when nitrogen was apparently the limiting factor, it is postulated that the increase in water potential of the bud may accelerate protein synthesis, thereby enhancing the bud's capacity to compete for the limiting nitrogen supply.
The influence of simulated canopy light on the growth of six acrocarpous moss species
Authors: Hoddinott John , Bain John
Published: November 2007

Six moss species were grown in two growth chambers with similar environmental conditions except for their ç ratios (E660:E730). One chamber simulated a sunlit situation the other a subcanopy shade situation. Different growth responses were observed for several species in the two chambers, which were often in the opposite direction to observations made on vascular plants. The ç ratio may be an important factor in regulating the distribution of mosses in the natural environment.
Potential for nitrogen fixation in the rhizosphere and habitat of natural stands of the wild rice Zizania aquatica
Authors: Ogan M. T.
Published: November 2007

The potential for nitrogen fixation in the rhizosphere and habitat of natural stands of Zizania aquatica (L) was studied by the acetylene reduction method. The data obtained suggested that this potential exists in the water column, the rhizosphere soil of the wild rice habitat, and on the root surfaces of the plants.In situ determination of rates of nitrogen fixation in the water column showed low but significant levels only in late spring – early summer and the rate was thought to be dependent on the presence of the blue-green algae Aphanizomenon. Laboratory experimental evidence showed that acetylene reduction by rhizosphere surface soil was attributable to Oscillatoria species while bacteria were more active in the subsurface soil and on the root surfaces. The bacteria-mediated nitrogenase activity was often preceded by a long lag period. The heterotrophic bacteria involved were enumerated, isolated, and characterised and they belong to the genera Azotobacter and Clostridium. Algal components of blooms occurring within the stands of Zizania at various times were identified.
Ultrastructure de l'hyphe végétatif de Sclerotinia fructigena
Authors: Najim L. , Turian G.
Published: November 2007

Vegetative hyphae of Sclerotinia (Monilia) fructigena (Ader and Ruhl) show a sharply polarized distribution of their organelles. In their tip, the "Spitzenkörper" made up of a microvesicular aggregate is well delimitated and surrounded by apical vesicles which can fuse with the plasmalemma. Excluded from the hyphal tip, mitochondria are elongated in the apicobasal polarity and in contact with numerous and often voluminous lipid globules. It appears that these lipid globules originate from the endomembranous system of the hyphae. The endoplasmic reticulum extends into pseudogolgi cisternae apparently generating apical vesicles. In the new hyphal branches, polarity seems to be initiated by the newly oriented endoplasmic reticulum from which originate microvesicles later aggregating into the new "Spitzenkörper." An elaborate system of microtubules also seems implicated in the further maintenance of the polarity of the growing hyphae. Microbodies with pseudocrystalline inclusions are also oriented according to the developmental polarity.
Early modifications of the internodal anatomy of Glycine max sprayed with 2,4-DB
Authors: Pizzolato Thompson Demetrio , Regehr David L.
Published: November 2007

An aqueous spray of 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) induces anatomical changes in young Glycine internodes. Four days after spraying, the first symptoms appear outside the cambium when the interfascicular parenchyma cells and the adjacent cortical parenchyma cells enlarge and divide in several planes. Four days later, the metaphloem parenchyma cells in many of the leaf traces undergo considerable periclinal cell division and extensive radial cell enlargement. The phloem parenchyma cells of the late metaphloem and first secondary phloem enlarge and divide in a less orderly fashion. Fifteen days after treatment, the cortical parenchyma is modified into a band of radially seriate cells above the protophloem fibers. Products of this cambium-like region convert the cortex into a callus-like tissue. The size of starch grains is reduced initially in the phloem and xylem and later in the cortex. It appears that the stimuli produced by 2,4-DB move into the internode via the metaphloem of leaf traces. Despite the rapid obliteration of conducting phloem by the 2,4-DB induced stimulation of phloem parenchyma, an accelerated differentiation of secondary phloem compensates for this loss.
Reduced root and shoot growth caused by Erysiphe graminis tritici in related wheats grown in nutrient solution culture
Authors: Baenziger P. S. , Kilpatrick R. A. , Moseman J. G.
Published: November 2007

We determined the effects of infection by Erysiphe graminis f. sp. tritici on root and shoot growth of the susceptible wheat cultivar 'Chancellor,' of the intermediately resistant line C.I. 14122 and of the highly resistant line C.I. 14120. Lines C.I. 14122 and C.I. 14120 are near isogenic lines of 'Chancellor' that carry resistant genes Pm3c and Pm3a respectively, conditioning their resistance to E. graminis tritici. Seedlings were grown in nutrient solution culture, inoculated with cultured of E. graminis tritici, and harvested 21 days after inoculation. The root dry weight of ‘Chancellor' was 54% less than the root dry weight of the highly resistant line C.I. 14120. The root dry weight of the intermediately resistant line C.I. 14122 was 16% less than the root dry weight of the highly resistant line C.I. 14120. The shoot dry weight of ‘Chancellor' was 46% less than that of the highly resistant line C.I. 14120. Tiller number was also significantly reduced by E. graminis tritici.
Genera coelomycetum. XVII. New anamorph genera: Libartania and Plectronidiopsis
Authors: Raj T. R. Nag
Published: November 2007

Two new anamorph genera are described to accommodate Bartalinia themedae Hansf., Neorttiospora laserpiti Bres. and Dilophospora chilensis Speg.
Temporal and spatial patterns of carbon allocation in the canopy of white oak
Authors: McLaughlin S. B. , McConathy R. K.
Published: November 2007

The fate of photoassimilated 14C was followed by measuring 14C incorporation into leaf and branch tissues (≤ 5 years old) of two forest-grown white oak trees. Fate of 14C-labelled photosynthate was examined 7 days after 14CO2 uptake on live dates (April–October) during the growing season. Both upper and lower canopy positions were sampled. Incorporation of 14C into foliage was significant throughout the growing season. It ranged from 95% of the total 14C retained in April to 50% in October. Incorporation of 14C-labelled photosynthate into the canopy was highest in June and averaged 33% of gross photosynthetic production over the entire growing season. Higher retention of photosynthate in branches versus leaves was noted in the upper canopy than in the lower canopy during the middle and late growing season. Activity levels in tissues indicated that within-canopy sink strength was in the order acorns ≈ buds > leaves > branches. Translocation of initial 14C-labelled photosynthate from both leaves and branches was calculated based on 14C retention and estimated respiratory losses of leaf and branch tissues. These calculations indicate that leaves were still importing significant amounts of photosynthate in April when expansion was two-thirds complete. Translocation of 14C from the canopy during the remaining growing season amounted to 25–45% of gross photosynthesis. Our data indicate that seasonal demands of growth and maintenance of the forest canopy constitute a substantial sink for photosynthate allocation by white oak.
A review of the genus Protopiceoxylon with emphasis on North American species
Authors: Medlyn David A. , Tidwell William D.
Published: November 2007

Protopiceoxylon Gothan, a genus of Mesozoic wood, is reviewed with special emphasis on three North American species. Two new species of this genus are proposed. These are Protopiceoxylon resiniferous from the Upper Jurassic Morrison Formation of Utah and Protopiceoxylon canodense from the Upper Jurassic strata of British Columbia. Protopiceoxylon dacotense from the Lower Cretaceous(?) of South Dakota is redescribed. All species of Protopiceoxylon are compared as to their xylotomy and distribution. Nine species are considered valid. The combination of characters unique for this genus includes the occurrence of only vertically formed resin canals, abietinoid pitting of the rays, and relatively large diameter of the bordered pits on the radial walls of the tracheids. Affinity of the genus with extant Keteleeria is also considered.
The rapid isolation of photosynthetically active mesophyll cells from Asparagus cladophylls
Authors: Colman Brian , Mawson Bruce T. , Espie George S.
Published: November 2007

Mesophyll cells were isolated rapidly from the cladophylls of Asparagus sprengeri Regel, by gentle grinding of the tissue by hand. About 60 to 65% of the leaf cells on a chlorophyll basis were released, of which 85 to 90% were cells with an intact plasmalemma. The isolated cells had photosynthetic rates of 50 to 80 μmol O2 per milligram chlorophyll per hour at pH 7.2 and 25 °C although rates of 90 to 105 μmol O2 per milligram chlorophyll per hour were recorded. The apparent Km of photosynthetic bicarbonate uptake at pH 7.2 was 176 μM in air and 104 μM under nitrogen, which corresponds to apparent Km's of CO2 fixation of 23 μM and 13.5 μM respectively. The isolated cells maintained high photosynthetic rates for 50 h when stored in the light at 4 °C and for over 160 h after storage in the dark at 4 °C.
Responses of the phosphatase activity of the lichen Cladina rangiferina to various environmental factors including metals
Authors: Lane I. , Puckett K. J.
Published: November 2007

The characteristics of phosphatase activity of Cladina rangiferina (L.) Harm, have been studied. Calculations of enzyme activities were based on the liberation of p-nitrophenol from p-nitrophenyl phosphate. The phosphatase activity was found to be linear both with increasing sample size (enzyme concentration) and increasing time, showed highest activity at acidic pH, and had a Michaelis–Menten constant of 8.9 × 10−3 M. The enzyme activity was maximal in the range 61 ± 10 °C, was independent of light, and was completely eliminated by boiling the thalli. Various cations and anions were tested for their effect; uranyl and vanadyl ions inhibited activity by 60% whereas copper, nickel, and silver enhanced activity by 10%. The anions biselenite, cyanide, fluoride, molybdate, phosphate, and vanadate all greatly reduced activity (≥ 50%). Phosphatase activity was demonstrated in other lichen species.
Quantitation of slow rusting in seedling and adult spring wheat
Authors: Martin C. D. , Miller J. D. , Busch R. H. , Littlefield L. J.
Published: November 2007

Four lines and one cultivar of wheat were studied under controlled conditions to define quantitatively the slow-rusting response to Puccinia graminis f. sp. tritici. The number of uredia per square centimetre at the onset of sporulation and the size of uredia were the characters that most clearly separated the slow-rusting from the fast-rusting wheats. Once sporulation began, the percentage rust severity on leaf sheaths of slow-rusting and intermediate slow-rusting lines increased as rapidly as that of the fast-rusting cultivar or even more rapidly. Percentage rust severity on adult stems (leaf sheaths) in the greenhouse agreed more closely with field observations (leaf sheaths, true stems, and peduncles) than did the size and rate of development of uredia on seedling and flag leaves measured in the greenhouse. Rust development was generally similar for four wheats in adult stem (field data) and seedling (greenhouse data) studies. One line did not show a slow-rusting response in both stages of development. The slow-rusting response was not closely related to selected anatomical traits of the peduncle of wheats examined. Length of incubation time and (or) the subsequent rate of increase or uredial numbers per unit area may influence slow rusting.
Sexual and vegetative incompatibility reactions in Phellinus weirii
Authors: Hansen Everett M.
Published: November 2007

Phellinus weirii is a heterothallic basidiomycete lacking clamp connections. Compatible pairings of single-spore isolates have a changed colony morphology, faster growth, and fewer nuclei per cell than the single-spore isolates alone. Compatible pairings occasionally form basidiocarps in culture. Single-spore isolates from different fruiting bodies are sexually compatible; most single-spore isolates from the same fruiting body are incompatible. Vegetative incompatibility is manifested by a line of demarcation formed when two dissimilar heterokaryotic isolates meet. Line formation is a sensitive indicator of genetic differences between heterokaryons or between heterokaryons and homokaryons.
Nuclear condition and vegetative characteristics of homokaryotic and heterokaryotic isolates of Phellinus weirü
Authors: Hansen Everett M.
Published: November 2007

Phellinus weirii produces uninucleate basidiospores, a multinucleate, homokaryotic mycelium (mean of 3.2 nuclei per cell), and an irregularly binucleate, heterokaryotic mycelium (mean of 2.2 nuclei per cell). Homokaryons grow more slowly and appear more uniform in culture than heterokaryons, and do not form basidiocarps in culture. Homokaryotic and heterokaryotic isolates could be reliably distinguished using the combined characteristics, but not using any one character alone. Thirty isolates from infected trees were heterokaryotic, although numbers of nuclei were less regular than for isolates from basidiocarps.
The taxonomy of Bay of Quinte phytoplankton and the relative importance of common and rare taxa
Authors: Nicholls K. H. , Carney E. C.
Published: November 2007

A listing of some 330 algal taxa found in the plankton of the Bay of Quinte during 1975 has been compiled and an indication given of the relative abundance at each of the eight sampling locations. Some difficulties related to interpretation of data on species number or 'richness' are discussed. It is suggested that particular attention in future years be given to several little-known taxa whose distribution and abundance will likely change should the trophic state of the Bay of Quinte be altered. Several species found in the Quinte collections have been only rarely reported from other parts of the world. Taxonomic notes on some problematical or otherwise interesting forms are included.
The distribution of fungi in some alpine soils
Authors: Bissett J. , Parkinson D.
Published: November 2007

Comparisons were made of the soil fungi isolated from three diverse alpine sites. The sites studied were a grass slope (Bromus association) at 1900 m, an alpine meadow (Dryas association) at 2530 m, and a summit ridge (Oxytropis association) at 2840 m. The effects of season, soil depth, and substrate type on the distribution of fungi were also examined. In a principal component analysis, most of the variation in mycoflora composition was attributed to differences among the sites. All taxa tested using a factorial analysis of variance showed significant differences in isolation frequency among the three sites. About half showed significant variation with season. For total fungi, the effect of seasonal change was the smallest of the four factors studied. Seasonal changes were not unidirectional, instead the composition of the fungal community shifted to one extreme in summer, with the direction of this change later reversing to another extreme in the fall opposite to that of the summer. The frequency of occurrence of most taxa was inversely related to soil depth. However, Chrysosporium pannormn, Penicillium restrictum. Penicillium canescens, and sterile fungi showed the opposite trend.The fungal communities were characterized by a few frequently isolated species, and a much larger proportion of infrequently isolated forms. All the dominant species were also widely distributed in temperate soils. The less frequently isolated species were usually highly aggregated in their distribution, with localized densities often exceeding those of the most frequently isolated forms. This pattern of distribution may have resulted from specialization on a niche dimension that was not widely distributed in the soils studied. Dominant species were less aggregated and more widely distributed, possibly reflecting a broad or diverse niche space for these species.
Strasseria on Pinaceae in Canada
Authors: Parmelee J. A. , Cauchon R.
Published: November 2007

Strasseria geniculata (Berk. & Br.) Höhn. is described and illustrated for the first time from North America. The hosts, all in Pinaceae, are new records: Abies balsamea L., Picea glauca (Moench) Voss, Pinus resinosa Ait., and P. sylvestris L. Some comments on conidial formation are offered and 12 species of Strasseria on 11 host families are listed.
Dormancy studies in seed of Avena fatua. 10. On the inheritance of germination behaviour
Authors: Jana S. , Acharya S. N. , Naylor J. M.
Published: November 2007

Breeding experiments were performed with pure lines of Avena fatua differing characteristically in duration of primary seed dormancy. The results indicate that the parental lines differ for at least three genes controlling rate of afterripening. It is evident that at least two of these genes influence the rate of afterripening at different periods after seed maturation.
Evolution de la teneur en lipides du Leptosphaeria typhae en fonction de sa croissance et de sa reproduction sexuée
Authors: Vidal Gérard
Published: November 2007

Cultures of Leptosphaeria typhae submitted to nycthemeral photoperiods produced perithecia on the 7th day of growth. Control developed in darkness remained sterile. At the beginning of growth, fertile cultures had more lipids which contained more palmitic acid and less linoleic and linolenic acids than vegetative mycelia. After the first perithecia appeared, the evolution of lipid content was entirely reversed.
Size, productivity, and paleoecological implications of ericaceous pollen from Burns Bog, southern Fraser River Delta, British Columbia
Authors: Hebda Richard J.
Published: November 2007

Measurements of pollen tetrad diameters of eight ericad species from Burns Bog, Delta, B.C., showed that although diameters range continuously from 22 to 53 μm, groups of species can be recognized. These groups are ecologically significant with (i) small tetrads indicating dry habitats, (ii) intermediate tetrads indicating intermediate to dry sites, and (iii) large tetrads characteristic of wet habitat species. Pollen productivity of six of the above species varies, with those in dry sites producing much more pollen than species of wet habitats. Tetrad diameter spectra obtained from bog sediments under various ericad associations are dominated by tetrads of a diameter characteristically produced by the species growing at the site. Therefore fossil ericad assemblages can be interpreted on the basis of tetrad diameters.
Lycopods of Pennsylvanian age coals: Polysporia
Authors: DiMichele William A. , Mahaffy James F. , Phillips Tom L.
Published: November 2007

Permineralized specimens of Polysporia are described from coal balls of three Middle Pennsylvanian age coals of the Illinois Basin. Identification is based on the presence of Endosporites microspores and Valvisporites megaspores along with sporangial fragments in the axils of leaves interpreted as sporophylls. The shoots exhibit alternating fertile and vegetative zones. Vegetative leaves are larger than sporophylls which are often desiccated and folded back against the stem surface; a short zone of transitional sterile leaves is found between vegetative and spore-bearing zones. Ligule pits are present on the adaxial surface of vegetative leaves. The stems are essentially herbaceous but robust and 4–6 cm in diameter. Small amounts of periderm and wood were produced but primary tissues were not disrupted. Polysporia is the first herbaceous lycopod with an alternation of fertile and vegetative areas found in Pennsylvanian peats and is compared with Spencerites, Sporangiostrobus, and Lepidodendron dacrydioides (proposed vegetative stem of Sporangiostrobus) which are suspected to have similar structure. The rarity of Polysporia in coal balls and its frequent associations with Sphenophyllum, combined with low numbers of arborescent lycopods, Psaronius or Medullosa, suggest an environment of growth not frequently encountered in coal-ball studies of the swamps. Polysporia may have grown in marginal wetland environments where herbaceous and low shrubby plants predominated; this suggests that some Endosporites—rich coals of the Upper Pennsylvanian are derived in large part from marshland peats.
Colonization rates and growth responses of soybean plants infected by vesicular–arbuscular mycorrhizal fungi
Authors: Carling D. E. , Brown M. F. , Brown R. A.
Published: November 2007

The interactions between soybean plants and two species of mycorrhizal fungi were examined. The number of infection units in young seedlings was found to increase in the presence of increasing quantities of Glomus fasciculatus inoculum, until a maximum was reached. Soybean seedlings remained free of mycorrhizal infection during early stages of development. First infection units appeared 10–12 days after planting which was also the approximate time that rhizobium root nodules and tertiary roots were first observed. The response to colonization by vesicular–arbuscular mycorrhizal fungi was evident as early as 6 weeks after planting.
Tissue culture and organogenesis in the winged bean
Authors: Bottino P. J. , Maire C. E. , Goff L. M.
Published: November 2007

Seedlings of Psophocarpus tetragonolobus var. TPt2 were grown under sterile conditions on nutrient agar. Hypocotyl sections (0.5 cm) from 2-week-old seedlings were used to initiate callus on solid B5 medium with 0.5 mg/L 2,4-D. Callus was transferred into liquid B5 and MS media also containing 0.5 mg/L 2,4-D. Suspension cultures developed within 6 weeks, but could not be maintained longer than 3 months. However, when suspensions were transferred into medium containing MS salts, iron-EDTA, and the following organic compounds: inositol, thiamine, pyridoxine, nicotinic acid (0.5 mg/L), kinetin (0.3 mg/L), IAA (5.0 mg/L), 2,4-D (1.5 mg/L), and sucrose (40 mg/L), optimal growth resumed and has continued for 2 years with a doubling time of 57.6 h. Chromosome counts of the suspension culture cells show predominantly the diploid chromosome number of 2n = 18. Greening of callus occurred in the absence of exogenous hormones, but efforts to hormonally induce organogenesis from callus have succeeded only in promoting root formation.
Inception of the cupule of Quercus macrocarpa and Fagus grandifolia
Authors: Macdonald Alastair D.
Published: November 2007

The female inflorescence of Fagus grandifolia comprises two flowers; one flower terminates the first-order inflorescence axis, the other flower terminates the second-order inflorescence axis. Each flower is flanked by two cupular valves each of which arise in the axil of a bract. The two valves flanking the flower terminating the first-order inflorescence axis represent second-order inflorescence axes and the two valves flanking the flower terminating the second-order inflorescence axis represent third-order inflorescence axes. The four valves remain discrete. Each female flower of Quercus macrocarpa terminates a second-order inflorescence axis and is surrounded by a continuous cupule. The cupule first forms as two primordia in the axils of each of the two transversal second-order bracts. These cupular primordia represent third-order inflorescence branches. The cupule primordia become continuous about the pedicel by meristem extension. The cupules of Fagus and Quercus are homologous to the extent that they are modified axes of the inflorescence. This serves as a model to interpret the morphological nature of the fagaceous cupule.
Ultrastructure of the interaction between the take-all fungus and antagonistic bacteria
Authors: Faull J. L. , Campbell R.
Published: November 2007

The interaction between Gaeuinannomyces graminis and a bacterium, Bacillus mycoides strain 31, that reduced root lesions on wheat in field trials, was studied under gnotobiotic conditions. The ultrastructure of infection by G. graminis is described including the penetration of the cortex and formation of lignitubers. In the presence of the bacterium the hyphae of the pathogen are lysed and it is suggested that this lysis is the reason for the control of the disease. In field soils, bacteria and sometimes the fungal hyphae, were surrounded by clay particles; the possible importance of this association in the balance between the bacteria and the pathogen is discussed.
Chromosome numbers in Canadian Phegopteris
Authors: Mulligan Gerald A. , Cody William J.
Published: November 2007

Phegopteris connectilis (Michx.) Watt in Canada is commonly an apogamous triploid with the chromosone number n = 2n = 90. Apogamous tetraploid plants of this species, with the chromosome number n = 2n = 120, also occur at a few locations in Quebec, New Brunswick, and Nova Scotia. Although these tetraploids are assumed to have arisen through hybridization between apogamous triploid plants of P. connectilis and plants of the sexual diploid (n = 30, 2n = 60) P. hexagonoptera (Michx.) Fée, some of the tetraploids now occur outside of the present range of P. hexagonoptera. Frond characteristics are diagnostic in separating tetraploid P. connectilis from P. hexagonoptera but are not always reliable in distinguishing tetraploid from triploid plants of P. connectilis.
Dwarf mistletoe seed capsule orientation and seed discharge in western hemlock
Authors: Thomson A. J.
Published: November 2007

The seed discharge of Arceuthobium tsugense is closely related to the orientation of the seed capsule. The distribution of capsule orientations may therefore be used as a guide to the discharge pattern. With plants on the periphery of the crown, the azimuth orientation of the capsules directs seeds outward from the crown, whereas plants within the crown have an inward direction of azimuth capsule orientations. The distribution of vertical orientation angles is related to the growth angle of the branch bearing the infection. Infections near the crown periphery would appear to be more related to spread of infections, whereas those within the crown are related to intensification.
Occurrence of the ectomycorrhizal fungus Pisolithus tinctorius in Ontario
Authors: Malloch D. , Kuja A. L.
Published: November 2007

The ectomycorrhizal species Pisolithus tinctorius is reported in eastern Canada for the first time. One collection occurred on a mine tailing near Sudbury and a second in an undisturbed site near Georgian Bay.
Etude de la dynamique de l'azote à haute altitude. I. Fixation d'azote (réduction de l'acétylène) par Alnus viridis
Authors: Moiroud André , Capellano André
Published: November 2007

During two vegetative seasons (1977, 1978), Alnus viridis Chaix root nodules were incubated in the field and assayed for nitrogen fixing activity by acetylene reduction method. In green alder the nitrogenase activity took place with the first opening of buds (June); maximum values were attained in July–August; the activity decreased steadily until leaf fall, and then ceased. Diurnal fluctuations in acetylene reducing activity were observed, the 1400-hour values were twice those of 1000 hours. The optimal temperature for nitrogenase activity was below 20 °C; this fact would be in relation with better adaptation of Alnus viridis to cold climate. The nodular biomass being only 40 kg/ha, the nitrogen fixed during the vegetative season (mid-June to mid-October) was only about 8 kg/ha. Symbiotic fixation accounted for only 10% of the nitrogen requirements of green alder.
Yield response of winter wheat to chronic doses of ozone
Authors: Heagle Allen S. , Spencer Suzanne , Letchworth Michael B.
Published: November 2007

The relative sensitivity of 11 soft red winter wheat, Triticum aestivum L. cultivars, exposed as young plants to ambient levels of ozone (O3) was determined. On the basis of the shoot dry weight response, the cultivar Holly was determined to be significantly more sensitive than Oasis or Coker 47-27; Blueboy II showed intermediate sensitivity. Plants of these four cultivars, grown in pots or in the ground, were exposed for 54 days in open-top field chambers to different O3 concentrations added to existing levels of ambient oxidants for 7 h/day. The effects of O3 on foliar injury, growth, and yield were determined. For the four cultivars combined, the threshold O3 concentration (7 h/day seasonal mean) for significant injury and decreased growth and yield was between 0.06 and 0.10 ppm. For potted plants exposed to 0.10 and 0.13 ppm O3, seed weight yields were 10 and 27% less, respectively, than for those grown in "charcoal-filtered-air" chambers (0.03 ppm O3). For plants in the ground exposed to 0.10 and 0.13 ppm O3, the yields were 16 and 33% less, respectively, than for those at 0.03 ppm O3. The relative sensitivity of cultivars to O3 as young plants could not be used to predict O3 effects on seed yield.
An ultrastructural study of Triticum monococcum cell suspension cultures during aging and after treatment with the herbicide Diclofop-methyl (methyl-2-(4-(2′,4′-dichlorophenoxy)phenoxy)propanoate)
Authors: Davis David G. , Brezeanu Aurelia
Published: November 2007

Cell suspensions from root-derived callus tissues of Triticum monococcum L. were examined during growth and senescence. The fine structure of control cultures was compared with the ultrastructural modifications in cultures treated with the compound, methyl-2-(4-(2′,4′-dichlorophenoxy)phenoxy)propanoate (Diclofop-methyl). The control cell suspensions were observed during the cell division phase, the log phase, and the early stationary phase of growth. Senescence is characterized by a loss of ribosomes, alteration of internal membranes of the plastids, vesiculation, formation of granular material in the cytoplasm, rupture of the tonoplast, and an increase in number of lipid bodies. Cells in advanced stages of senescence had few organelles, but rather the cytoplasm consisted almost exclusively of lipid bodies and vesicles. The fine structure of the nuclei and mitochondria was least affected during aging. The ultrastructural effects of herbicide treatment did not completely parallel those of senescing cells, although any distinctions were difficult to sort out. The intensity of herbicide damage depended on both concentration and time (and undoubtedly the physiological state of any particular cell at the time of treatment). Low concentrations (4 μM) at 12 h resulted in plastid damage (analogous to chloroplast damage in photosynthetic tissues treated with herbicides) and in the formation of some myelin figures. At 20 μM concentration for 12 h, very extensive formation of myelin figures was observed in all cells. By 70 h, cells treated with 4 μM herbicide ranged from those with little or no damage to cells with extensive vesicle formation. In contrast, all cells treated with 20 μM herbicide at 70 h were damaged greatly. Some nuclei were present, although the nuclear envelopes were altered. Most organelles were barely recognizable. Extensive vesiculation and lipid formation occurred. These effects were more pronounced in cells treated with 40 μM herbicide at 70 h than in cells treated with lesser concentrations for shorter times. In this case, some organelles were recognizable (plastids and mitochondria) but they were abnormal in that the contents were often granular with only remnants of membranes. Some cells appeared as though the physiological processes were stopped so rapidly that hydrolytic enzymes could not function totally.
Ultrastructure of septal pore apparatus in the lamellae of Nematoloma puiggarii
Authors: Khan S. R. , Kimbrough J. W.
Published: November 2007

The lamellae of Nematoloma puiggarii have dolipore–parenthesome septa like the majority of the basidiomycetes. The septal pore canal is almost always transected by a central electron-dense zone. Often two more electron-dense zones, one on each side of the central one, are present in the canal. Pore canal openings are normally occluded by granular electron-dense plugs which are ring like in subbasidial and subhymenial septa and appear solid in some tramal septa. A hemispherical fibrous outer cap is always present outside the parenthesomes of subhymenial septa. Tramal septa do not have outer caps, and the subbasidial septa have them only on the subhymenial sides. The outer caps are usually delimited externally by either the cisternae of endoplasmic reticulum or by the tonoplast of adjacent vacuoles.
Impact of leaf-feeding insects on three bog ericads
Authors: Reader R.
Published: November 2007

In 1978, polyphagous larvae of the chain-dotted measuring worm (Cingilia catenaria (Drury)) (Lepidoptera: Geometridae) completely defoliated three species of ericad at the Luther Marsh bog in southern Ontario, but consumed less than 1% of the ericad leaf area each year between 1974 and 1977. The three ericads, bog laurel (Kalmia polifolia Wang.), leatherleaf (Chamaedaphne calyculata (L.) Moench.), and Labrador tea (Ledum groenlandicum Oeder.), were equally effective in defending leaves against all herbivores except larvae of C. catenaria, to which all were equally susceptible at high larval density. During the study period the frequency of intense herbivory was not great enough to seriously diminish the advantage of nutrient conservation associated with the 2-year leaf-retention period exhibited by these ericads.In laboratory feeding trials involving an unlimited food supply, C. catenaria larvae preferred leaves of K. polifolia and C. calyculata over L. groenlandicum leaves. Chemical feeding deterrents such as condensed tannins, although present in relatively large concentrations in the leaves, appeared to be less important than nutrients, such as nitrogen and carbohydrates. Pubescence on the undersides of L. groenlandicum leaves probably acted as a physical deterrent to larval feeding. The possession of antiherbivore leaf characteristics (e.g., thick cuticle, condensed tannins, terpenes, pubescence) by these three ericads may reflect selective pressure by herbivores in the past and (or) current edaphic constraints (i.e., limited water availability in winter and lack of nitrogen and phosphorus during the growing season).
A new Nitschkia on western conifers and its probable microconidial state
Authors: Funk A.
Published: November 2007

A new species, Nitschkia molnarii (Ascomycetes: Nitschkiaceae), is described from Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) in coastal British Columbia, Canada. A microconidial state closely associated with the ascocarps is described, but not separately named.
Acremonium boreale n.sp., a sclerotial, low-temperature-tolerant, snow mold antagonist
Authors: Smith J. Drew , Davidson John G. N.
Published: November 2007

A previously undescribed, sclerotial, low-temperature-tolerant fungus with orange sclerotia, is common on a wide range of plant species and substrates in Western Canada. It is often associated with snow mold complexes. It has also been found in eastern Canada and Norway, indicating a circumpolar distribution. It is described as Acremonium boreale n.sp. Some isolates were antagonistic towards common snow molds, viz. Fusarium nivale, Sclerotica borealis, Typhula ishikariensis var. ishikariensis and var. canadensis, and the nonsclerotial low-temperature basidiomycete in culture at low temperatures. Although it was weakly parasitic towards two grass species, its main ecological importance seems to be as an invasive primary saprophyte on a wide range of substrates. It may play a significant role in determining the nature and intensity of damage in snow mold complexes.
Seasonal changes in carbohydrate levels in tissues of Carex lacustris
Authors: Roseff Scott J. , Bernard John M.
Published: November 2007

Seasonal changes in total nonstructural carbohydrates (TNC) levels in aboveground and belowground tissues of Carex lacustris were determined. TNC concentrations of aboveground tissues averaged 15–20% of the dry weight throughout the year, ranging from 31.3% in newly emerged shoots in September to 3.1% in mostly dead shoots in December. Belowground, TNC concentrations ranged from a low of 16.4% in young rhizomes in midsummer to a high of 44.9% in late October.TNC content of shoots was 68.5 g/m2 on May 5, increasing to a peak of 224.5 g/m2on August 5. Levels declined to a low of 31.6 g/m2 by December 5, of which 74% was found in young shoots about to overwinter. Belowground TNC was 107.5 g/m2 on May 8, declined somewhat into June, then increased to a maximum of 240 g/m2 on October 24. The data indicate these belowground reserves are important for the species to overwinter successfully.The difference between the minimum TNC content of the sedge biomass in late May and the peak in October represented a gain over the summer of approximately 205 g/m2.
Aulacomnium heterostichoides sp.nov., an Eocene moss from south central British Columbia
Authors: Janssens Jan A. P. , Horton Diana G. , Basinger James F.
Published: November 2007

Aulacomnium heterostichoides Janssens, Horton, and Basinger is described as new from Eocene sediments located near Horsefly, B.C. It is characterized by spirally arranged, oblong leaves, which are slightly asymmetric by the unequal laminae in the lower one-third; irregularly, coarsely toothed upper margins with the teeth both multicellular and multiseriate; a strong costa, which ends near the apex; upper and basal laminal cells which are more or less isodiametric. These character states indicate a very close relationship to Aulacomnium heterostichum.Palynological studies indicate that Aulacomnium heterostichoides grew in a temperate, deciduous forest with species of Alnus, Carya, Pinns, Quercus, Taxodium, and Tilia, as well as other deciduous and coniferous trees. Extant populations of A. heterostichum commonly occur in a similar habitat along streams in the mesic, deciduous forests of eastern Asia and eastern United States.There is considerable fossil evidence which shows that vascular plants currently restricted to eastern Asia and eastern North America, occurred in the intervening areas across continental North America in Tertiary times. Our report of A. heterostichoides is the first indication, based on a fossil specimen, that bryophytes presently associated with the disjunct deciduous forests of eastern Asia and eastern North America were earlier associated with some elements of these forests in localities beyond the present range of such taxa.
Vegetation ecology and classification in the Antarctic Zone
Authors: Longton R. E.
Published: November 2007

A review is presented of plant community ecology within the Antarctic Botanical Zone. The vegetation is formed largely of mosses, lichens, and algae but hepatics also occur and two native species of flowering plants are locally abundant. A hierarchical classification is outlined in which the vegetation is divided into two formations dominated, respectively, by flowering plants and by cryptogams. The antarctic nonvascular cryptogam tundra formation comprises eight physiognomically distinct subformations, while associations within subformations are recognized on the basis of constancy, and sociations within associations by cover of the dominant species. It is shown that the classification is applicable at a range of climatically diverse localities in the maritime and continental Antarctic regions. The position of the Antarctic communities in relation to worldwide and polar–alpine vegetation classification is briefly discussed.Low summer temperature is suggested as a major factor determining the essentially cryptogamic nature of Antarctic vegetation. Water availability and exposure appear to be of primary importance in controlling the distribution of the cryptogamic growth form types, both within localities in the vegetationally relatively diverse maritime Antarctic, and between the maritime and the more sparsely vegetated continental regions. With certain exceptions, there appear to be few successional relationships between the major vegetation types.