bluuebunny/crossref_metadata_2025 huggingface dataset:
A contribution to the taxonomy of Arctostaphylos uva-ursi
Authors: Packer John G. , Denford K. E.
Published: September 2008

The infraspecific taxa of Arctostaphylos uva-ursi are reevaluated with respect to the pubescence of the young branches, chromosome number, and phenolics. It is concluded that the best taxonomic treatment for the time being is to recognize four taxa at the subspecies level, ssp. uva-ursi, ssp. adenotricha, ssp. stipitata, and ssp. longipilosa, the two latter being new taxa not previously described.
Verticillium wilt of chrysanthemum: anatomical observations on colonization of roots, stem, and leaves
Authors: Alexander Susan J. , Hall Robert
Published: September 2008

The morphology and distribution of Verticillium dahliae Kleb. within the ornamental chrysanthemum (Chrysanthemum morifolium Ramat) was determined at intervals after placement of rooted cuttings into infested potting mix. Most infection sites on the root system occurred on roots that developed after potting. Estimates of the number of infection courts per 100 cm of root ranged from 5.6 to 15.8. Root-cortex cells responded to invasion by producing lignitubers and a dark pigment. Microsclerotia had formed within root-cortex cells 8 days after potting. Hyphae, conidia, and conidiophores were observed throughout the vascular system. Hyphal widths ranged from 1.3 to 3.6 μm; conidial dimensions ranged from 1.8 × 3.6 to 2.6 × 5.8 μm. Colonization of vessels of stem and leaves was initially discontinuous and was therefore presumably initiated by conidia. Hyphae in root and stem vessels were generally narrow and there was rarely more than one strand per vessel. Occlusion of the lumen or pore plate of vessel elements in root and stem by hyphae, conidia, gums, gels, or tyloses was not observed. Conidia accumulated in petioles and basal portions of the midrib and lateral veins of leaves, often blocking pore plates. Initially, hyphae in leaf vessel elements were narrow but as wilt symptoms appeared, wide sinuous hyphae predominated, often coursing freely among adjacent vessel elements through pit-pairs and pore plates. Mycelium and conidia appeared to occur sufficiently abundantly in leaf vessels to significantly restrict water flow.
Osmotic and specific ion effects on the germination of alfalfa
Authors: Redmann R. E.
Published: September 2008

Inhibition of seed germination in alfalfa varieties Rambler, Roamer, and Beaver by iso-osmotic potentials of different substrates varied widely. Sodium and potassium sulfate and sodium chloride were most inhibitory. Chlorides of potassium and magnesium and magnesium sulfate were least effective; mannitol and polyethylene glycol were intermediate. Ion toxicity was determined by measuring germination recovery after treatment with solutions containing equivalent weights of salt. No salts were toxic at 25 meq/liter. Sodium sulfate and magnesium chloride appeared highly toxic at 200 meq/liter; other salts were less toxic, with sodium chloride showing the least effect of all. All salts were highly toxic at 400 meq/liter. Germination recovery after treatment with polyethylene glycol and mannitol was good, clearly distinguishing osmotic and specific ion effects. Variety Beaver was the most tolerant of both the osmotic and toxic effects of salt.
Experimental hybridization in Xanthium strumarium of American complexes with diverse photoperiodic adaptation
Authors: McMillan Calvin
Published: September 2008

Plants with different critical periods of darkness for flowering were hybridized for a comparison of photoperiodic adaptation. The reciprocal F1 progenies showed a photoperiodic requirement which was intermediate between those of the parental types. The leaf and bur morphologies and the sesquiterpene lactones of the hybrids also showed intermediacy. The American morphological complexes involved in the artificial crosses were italicum, chinense, cavanillesii, and pennsylvanicum and included indigenous populations as well as those introduced to Australia. The plants that were hybridized were from lower latitudes and had apparent critical nights of 9.25–9.5, 9.75, 10, 10.25, and 10.5 h.
Disappearance of IAA in the presence of tissues of sunflowers infected by Plasmopara halstedii
Authors: Cohen Yigal , Sackston W. E.
Published: September 2008

Stem elongation of sunflower plants inoculated at the two-leaf stage through apical buds with Plasmopara halstedii was greatly inhibited. Systemically infected plants did not show normal phototropic and negative-geotropic responses. There was a positive correlation between stunting of infected plants and ability of stem slices to remove indoleacetic acid (IAA) from test solutions. IAA disappearance in the presence of stem slices of infected plants was also highly correlated with area of mildew symptoms on leaves. Although IAA disappeared in the presence of all diseased tissues, leaf tissues were least active. No IAA disappeared in the presence of sporangia of the pathogen. These results explain reduced levels of IAA observed in mildew-infected sunflowers in earlier studies and may account for the characteristic stunting of systemically infected plants.
A contribution to the taxonomy of Viola adunca
Authors: McPherson G. D. , Packer John G.
Published: September 2008

This study has confirmed the occurrence of diploid and tetraploid races in Viola adunca J. E. Smith, in both of which sexual reproduction is normal. Also found to exist is a triploid which is sterile. The tetraploid is distributed widely in western Canada and the two races appear to be virtually allopatric. Differences have been found which permit separation of the races on morphological grounds. Taxonomic recognition of the two chromosome races is recommended but is not included here because necessary information on the type specimen is not available at the present time.
Parameters for growth measurement in suspension cultures of plant cells
Authors: Rose Dyson , Martin S. M.
Published: September 2008

Well-adapted cells, which had been initiated from root tissue of Ipomoea and of Daucus carota, were grown in 7.5-liter stirred-jar fermenters, and both the cells and media were analyzed for major components at intervals during the growth period. Controlled variables included the size of inoculum, the amount of sucrose, and the source and amount of nitrogen in the media.The data obtained indicate that there are two distinct growth phases in the development of batch cultures of these cell lines. The first, which we term "cytoplasmic growth phase," begins immediately upon addition of inoculum to fresh medium and is characterized by a high rate of nitrogen uptake and metabolism relative to the increase in cell dry weight. The second, or "maturation phase," is characterized by large increments in dry weight and total cell carbohydrate relative to the increments in cell nitrogen. It is suggested that the classical lag, log, and stationary phases of bacterial growth could apply only to the early hours of cytoplasmic growth, if indeed they are relevant at all.
Discontinuities in the callose wall, intermeiocyte connections, and cytomixis in angiosperm meiocytes
Authors: Whelan Ernest D. P.
Published: September 2008

Discontinuities, considered to be holes, were observed in the meiocyte callose wall of 25 dicotyledon and 5 monocotyledon taxa investigated by phase-contrast and Nomarski interference-contrast optics. With the exception of the Helianthus spp., where regular distribution was observed, the holes were confined to two to four discrete areas of the callose wall. Hole size was highly variable; the largest, of about 2 μm diameter, occurred in lupin (Lupinus polyphyllus Ldl.). Cytoplasmic connections between neighboring meiocytes and (or) cytomictic phenomena were observed in 13 of the 30 taxa investigated.
Pollen morphology and the infrageneric classification of Minuartia (Caryophyllaceae)
Authors: McNeill J. , Bassett I. J.
Published: September 2008

Pollen size, type and number of apertures, and exine thickness are reported for 25 species representative of all four subgenera of Minuartia (Caryophyllaceae) and of the related genera Honkenya and Wilhelmsia. The pollen of the species of Minuartia subgenus Rhodalsine is trizonocolpate with a relatively thin exine and it differs from that of all other species of the subfamily Alsinoideae. Species of this subfamily apparently all have pollen grains that are pantoporate with a thick exine. The relationship of the species of subgenus Rhodalsine with those of Spergularia (subfamily Paronychioideae), a genus which has pollen grains similar to those of subgenus Rhodalsine, is discussed. A new name, Minuartia webbii McNeill and Bramwell, is proposed.
Destruction of enzymatic activities of corn and soybean leaves exposed to ozone
Authors: Leffler H. R. , Cherry Joe H.
Published: September 2008

Experiments were conducted to determine the effects of a single ozone exposure on selected enzymatic activities and chlorophyll contents of corn and soybean seedlings. Both nitrite reductase activity and chlorophyll content of the seedlings were found to be quite sensitive to ozonation and were seen to decrease as much as 50% after exposure to 80 parts per hundred million (pphm) ozone. After exposure to lower levels of ozone, less-pronounced decreases were observed. Nitrate reductase activity was reduced only after exposure of seedling leaf tissues to high concentrations of ozone. These results are discussed in relation to the concept of a two-phase response to oxidant exposure. The first phase is at the chloroplast level and is quite sensitive to the low as well as the high concentrations of ozone; the second is at the cellular level and is relatively resistant to all but the highest ozone concentrations.
Nova Scotian fungi. New and noteworthy species of Hygrophorus
Authors: Grund Darryl W. , Harrison K. A.
Published: September 2008

This brief paper considers five species of Hygrophorus collected in Kings Co., Nova Scotia, during 1972–1973. One variety is described as new, and three species are reported for the first time from the Maritime Provinces. Three of the five species included are not adequately described or illustrated in previous publications.
Conidiophore and conidium ontogeny in Spegazzinia tessarthra
Authors: Cole Garry T.
Published: September 2008

Spegazzinia tessarthra (Berk. & Curt.) Sacc. is a member of a unique group of hyphomycetes whose conidiophores undergo 'basauxic' growth. In this initial developmental study, time-lapse photomicrographic analyses of two kinds of conidia are presented and ultrastructural features of the fertile cells are examined.
Glyphium in western Canada and United States
Authors: Goree H.
Published: September 2008

The hysteriaceous genus Glyphium (Ascomycetes) is represented in western Canada and United States by two species. The inland species, G. corrugatum (Ell.) comb. nov. (≡ Acrospermum corrugatum Ell.), has ascospores which fragment in the ascus. The coastal species, G. elatum (Grev. ex Fr.) Zogg, has ascospores which remain intact.
Effects of carbon dioxide on Pharbitis, Xanthium, and Silene in short days
Authors: Purohit A. N. , Tregunna E. B.
Published: September 2008

The flowering response and other morphological characters of Pharbitis nil, Xanthium pennsylvanicum, and Silene armeria were studied in environments with different levels of carbon dioxide and oxygen under short-day conditions. Different light sources and intensities were also tested. Irrespective of the light source and intensity used, higher levels of carbon dioxide delayed or inhibited flowering as well as other morphological characters of the short-day plants but induced flowering in the long-day plant. Dry weight per unit leaf area as well as total chlorophyll increased with carbon dioxide concentration. The results are discussed in relation to some other recent reports, and it is proposed that large variations in photosynthetic rates of plants probably alter their photoperiodic response.
Effect of ionic environment on the response of the sensory hair of Venus's-flytrap
Authors: Jacobson Stuart L.
Published: September 2008

Single cells of multicellular sensory hairs excised from the leaf of Venus's-flytrap were impaled with KCl-filled micropipettes. The cellular resting potential and the electrical response to mechanical stimulation were measured. The effect of changing the ionic composition of the fluid perfusing the hairs was examined by systematically varying the concentration of Na+, K+, Mg2+, Ca2+, Cl−, and H+. The resting potential was only affected significantly and consistently by potassium ion. The amplitude of the resting potential decreased linearly as log [K+] in the perfusing fluid increased. The amplitude of the response potential was affected by all of the ions tested except sodium. Response amplitude decreased linearly as log [K+] for low [K+] and in a more complex fashion for higher [K+]. The amplitude of the response potential increased linearly as log [Mg2+] or log [Ca2+] increased. Changes of [Cl−] and [H+] affected the response potential in a complicated way.
Etude cinétique, en microscopie électronique, des interactions entre Colletotrichum lagenarium et les cellules foliaires de Cucumis melo
Authors: Dargent Robert , Touzé André
Published: September 2008

The ultrastructure of apparently healthy mesophyllic cells of muskmelon seedlings is briefly described.Electron micrographs of invaded cells 72 h after inoculation show the intracellular localization of the pathogen and the alteration of the host cell wall in contact with the hyphal apex, the capsulation of hyphae by the host-cell plasmalemma, and the swelling of chloroplasts, nuclei, and mitochondria.When symptoms appear, about 96 h after inoculation, electron micrographs show advanced host cell degeneration, and the fine structure of invading hyphae, including septa formation.
Spores and septa in the genus Dipodascus
Authors: Ru N. J. W. Kreger - van , Veenhuis M.
Published: September 2008

Electron microscopy of the septa in hyphae of Dipodascus species showed a narrow, central pore in D. uninucleatus and plasmodesmata in D. aggregatus, Ascospores in D. uninucleatus are small, oval, or reniform; in D. aggregatus they are much bigger with a wall which is first narrow and later expands considerably. The description of the spores of the type species, D. albidus, of which no strains were available for examination, agrees with that of D. aggregatus. Apart from the features mentioned above, D. uninucleatus differs from D. albidus and D. aggregatus in other important characteristics, such as the method of gametangia formation and the structure of the cell wall.
Genetic limitations on models of specific interactions between a host and its parasite
Authors: Person Clayton , Mayo G. M. E.
Published: September 2008

Specific interaction between a resistance gene (R gene) of the host and an avirulence gene (A gene) of the parasite is the basis of the gene-for-gene relationship. R and A genes are conditional genes, capable of associating with either of two phenotypes depending on the presence or absence of the other. Although avirulence usually segregates as a dominant character, microevolutionary history suggests that in its primary function an A gene associates not with avirulence but with virulence, also that R:A interaction generates a “stop signal,” which prevents disease development, and finally that the primary function of a recessive a-gene, when it replaces a dominant A gene, is one of negating the stop signal. Where several gene-for-gene relationships operate simultaneously, a single R:A interaction is sufficient to prevent disease development. R and A genes occupied in R:A interaction are thus epistatic over those which are not. Because of the characteristics of the gene-for-gene relationship, definite limitations are imposed on genetic study. In any genetic study there may be, because of these limitations, contributing genes in both the host and the parasite which are not detected.
The effect of salinity and temperature on seed germination and growth of Hordeum jubatum
Authors: Ungar Irwin A.
Published: September 2008

Studies on the germination of Hordeum jubatum seeds indicate that they were highly tolerant of salinities up to 1.0%, with little reduction in germination. Each increase in salt concentration did, however, delay the time of germination. Seedling growth proved to be more sensitive than germination to salinity stress, with newly germinated plants showing a decrease in size with each salinity increment. Results of growth studies were similar to those in germination tests; plants decreased in size with decreased osmotic potential of the salt solution. The germination stage and later periods of active growth were nearly equal in their ability to withstand salinity stress.
Comparison of polyphenols and related enzymes in the capsule and nodal tumor of Nicotiana plants
Authors: Sheen S. J. , Andersen R. A.
Published: September 2008

Extracts of capsules of Nicotiana tabacum cv. Burley 21 and nodal tumors and capsules of a genetically tumor-prone amphiploid N. suaveolens × N. langsdorffii had a similar composition of phenolic compounds. Dihydroxyphenols, predominantly chlorogenic acid, accumulated to 4% and 13% of the dry weight in the young and old tumors, respectively. In situ synthesis of chlorogenic acid in tumor tissues was demonstrated by incorporation of L-phenylalanine-U-14C. Quantities of polyphenols also increased as floral tissue developed from fertilized flower to capsule. The immature capsule and tumor tissues contained more polyphenoloxidase but less peroxidase than the leaf. Peroxidase zymograms, soluble proteins, and alkaloids in tumor extracts resembled those in capsule extracts. It is suggested that these biochemical similarities may reflect a common mode for the regulation of cell proliferation in tobacco capsules and nodal tumors.
Temperature effects on growth, sporulation, and germination of some “aquatic” hyphomycetes
Authors: Koske R. E. , Duncan I. W.
Published: September 2008

Twelve species of "aquatic" hyphomycetes isolated from terrestrial habitats were grown in agar cultures at 5, 10, 15, 20, and 25C. The optimum temperature for mycelial growth of most species was 20C. Sporulation generally was favored by temperatures lower than or equal to that for maximum mycelial growth. Conidium germination by nine species was 100% after 24 h on water agar at 10-25C. Conidia of species with a low optimum temperature for sporulation were more seasonal in occurrence than were species that sporulated well from 10 to 25C.
The aqueous extraction of protein from plant tissue with the use of electrodialysis
Authors: Frenkel Chaim , Hess Charles E.
Published: September 2008

An electrodialysis system was used for the aqueous extraction of protein from frozen tissue of mung bean (Phaseolus aureus Roxb.) hypocotyl followed by gel electrophoresis and assay of polyphenol oxidase, esterase, and fungal glucose oxidase isozymes. The isozymes tested showed a consistent increase in activity with the increase in current, between 0 and 100 mA, suggesting that current application can overcome, in part, alterations in protein fraction during the aqueous extraction of plant tissue. Details of the extraction procedure and the construction of the electrodialysis system are described.
Intraspecific competition in experimental populations of weeds
Authors: Deschênes J. Marc
Published: September 2008

Red fescue (Festuca rubra L.), yarrow (Achillea millefolium L.), and mouse-eared chickweed (Cerastium vulgatum L.) were seeded at six densities under greenhouse conditions. Total dry matter production per pot (shoots and roots) increased as density increased for every species until a point was reached where a further increase of the density did not result in a higher production per pot. All species produced about the same shoot yield per pot. Root production per pot, however, was different among the species. The shoot–root ratio was the highest for mouse-eared chickweed, the lowest for red fescue, and intermediate for yarrow. All species exhibited fairly high germination and very low mortality, except yarrow. The three species displayed considerable plasticity in yield and in seed production per pot from low to high densities. The reproductive behavior varied between the species. Red fescue remained vegetative. Sexual reproduction of yarrow decreased drastically with increasing density. Mouse-eared chickweek maintained a large seed production over the whole range of densities. The population of the respective species seemed regulated by (1) individual plasticity and vegetative reproduction (red fescue), (2) individual plasticity, mortality, and limited seed production (yarrow), and (3) individual plasticity and high seed production (mouse-eared chickweed).
Blue-light-enhanced nitrate reductase activity in etiolated pea terminal buds
Authors: Jones R. W. , Sheard R. W.
Published: September 2008

Under conditions in which the light requirement for phytochrome mediation was inferred to be above saturation, white and blue lights enhanced the extractable nitrate reductase activity of etiolated pea terminal buds above the levels engendered by red and far-red lights. The regulation of nitrate reductase by light in the terminal buds appears to involve both phytochrome and a blue-sensitive high-energy reaction.
A periderm-color chimera in Abies
Authors: Zobel Donald B.
Published: September 2008

A chimera of red and yellow periderm color is described from a population intermediate between Abies concolor and A. grandis. Its formation probably followed changes in properties of apical initials, rather than in cells produced later in development. Apparently only a single genetic change can control this red–yellow periderm color difference.
Scanning electron microscopy of meiotic chromosomes of plants in situ
Authors: Whelan Ernest D. P. , Haggis G. H. , Ford E. J. , Dronzek B.
Published: September 2008

Scanning electron microscope studies of anthers of the Asiatic Lilium hybrid Enchantment and Solanum tuberosum L. cv. Netted Gem fixed in organic acid – alcohol type fixatives clearly revealed nucleoli, bivalents, and the meiotic spindle. Centromere regions could not be identified in pachytene bivalents, but areas of possible spindle attachment were evident for metaphase I – anaphase I bivalents.
A freeze-etch study of membranes in Plasmodiophora-infected and non-infected cabbage root hairs
Authors: Aist James R.
Published: September 2008

Membranes in cabbage root hairs infected by Plasmodiophora brassicae Wor. and in non-infected cabbage root hairs were investigated by the freeze-etching technique after glutaraldehyde fixation and glycerination. Non-infected root hair membranes were characterized for the first time by freeze etching, and their features were generally similar to those of membrane systems in other cell types. Plasmalemmasomes were observed in infected and in non-infected root hairs to have particle-free fracture faces. Similar fracture faces occurred in the outermost membrane of the envelope surrounding young amoebae in the root hairs; but, the plasma membranes of parasite cysts bore particles, and these showed an unusually strong tendency to adhere to the inner fracture face. In view of this new evidence the possible origin of the amoebal envelope is discussed. Striking developmental changes which occur in the interfacial membranes during the first 21 h of parasite growth are described and discussed.
The ascus apex of Ciboria acerina
Authors: Corlett Michael , Elliott Mary E.
Published: September 2008

The apical thickening of the ascus is composed predominantly of a relatively homogeneous and granular ground material laid down between the outer and inner wall layers of the ascus. A cylindrical pore with a central pore plug passes through the apical thickening. The cylinder is continuous with the outer ascus wall layer and extends into the lumen of the ascus. The plug, which obstructs the pore cylinder, consists of a material similar to or identical with the ground material in appearance. There is no outer ascus wall layer overlying the top of the pore plug but at the bottom the inner ascus wall layer separates the pore plug from the ascus lumen beneath. As a result of ascospore dispersal, the pore cylinder becomes everted.
Effet du potentiel osmotique du milieu nutritif des racines sur la pénétration et la migration du 42K fourni par voie foliaire
Authors: Chamel André , Bougie Bernadette
Published: September 2008

The uptake and translocation of 42K deposited on corn leaves (Zea mays L.) decrease significantly when the osmotic potential of culture solutions is lowered to –8.2 atm with polyethylene glycol (PEG 1000), [Formula: see text] before the application of 42K. The effect of this water stress on the translocation and distribution of 42K was not completely reversible in plants temporarily growing on the solution of smaller osmotic potential. After a 25-h period of recovery on a solution without PEG, there was always a difference between plants either not treated or treated previously with PEG. It appears clearly that the rates of translocation vary directly with the water content of plants.
Taxonomic and ecologie relationships between Picea glauca and Picea engelmannii
Authors: Daubenmire R.
Published: September 2008

Comparisons have been made of the morphologic characters of 30-tree populations of Picea distributed from near the Arctic Circle in Alaska, to near the southern boundary of Arizona. Included are 7 populations of P. glauca beyond the geographic range of P. engelmannii, 12 populations of P. engelmannii beyond the geographic range of P. glauca, and 14 populations in the area of sympatry. Hybridization is evident in all populations in the area of sympatry, despite the appearance of many low-altitude trees as pure P. glauca and many high-altitude trees as pure P. engelmannii. The geographic range of P. glauca influence has been extended farther south than previously recognized—to eastern Washington and northern Wyoming. Distinguishing characters commonly given in taxonomic keys are less reliable than absolute measurements of the ovuliferous scales. The Holocene history of Picea is speculated upon.
Bud morphogenesis of white spruce Picea glauca seedlings in a uniform environment
Authors: Pollard D. F. W.
Published: September 2008

Differences in height growth occurring between provenances of white spruce are associated with variation in number of needle primordia formed in the dormant bud. The number is influenced by seasonal pattern of initiation. This investigation sought to establish whether normal morphogenesis could proceed in a constant environment, and whether provenance variation would be expressed in the absence of seasonal changes. Bud development was induced in five provenances of white spruce by subjecting 1st-year seedlings to short photoperiods. Developing buds were sampled at 3-week intervals over a period of 12 weeks. Throughout this time, photoperiod was kept at 8 h; temperature was constant at 22.5 °C (72.5 °F). Observations revealed a morphogenetic pattern comparable with that of buds in older, field-grown trees. Needle initiation on the primordial shoot ceased 6 to 12 weeks after the inception of bud development. The inferred endogenous control of bud development and its effect on shoot growth was influenced genetically, with significant differences in needle initiation occurring among the provenances. Differences in bud development may allow early selection for fast growth and hardiness in this species. The results of this investigation identify the period immediately after shoot growth as critical for subsequent growth of nursery stock.
The nomenclatural implications of the taxonomy of Danthonia in Canada
Authors: Findlay Judy N. , Baum B. R.
Published: September 2008

An investigation of type collections of the 13 Danthonia species hitherto recognized for Canada as well as those of other pertinent species described from the United States is reported in detail. As a result of our designation of lectotypes and study of holotypes, we conclude that the correct names of the five species recognized earlier by Baum and Findlay are Danthonia californica Bolander, D. parryi Lamson-Scribner, D. sericea Nuttall, D. spicata (L.) Beauv. ex Roem. & Schult., and D. canadensis Baum & Findlay sp. nov.
Cytokinin production by the fungi Taphrina cerasi and T. deformans
Authors: Johnston James C. , Trione Edward J.
Published: September 2008

Cytokinins were released into chemically defined liquid media by cultures of Taphrina cerasi and T. deformans. The presence of the cell-division factors was demonstrated with the soybean callus tissue assay, which is specific for the detection of cytokinins. Paper chromatography in four solvent systems, in conjunction with bioassays, revealed that T. cerasi produced compounds that have migration patterns similar to those of zeatin, zeatin riboside, N6-(Δ2-isopentenyl) adenine, and N6-(Δ2-isopentenyl)adenosine. T. deformans produced compounds with chromatographic properties similar to those of zeatin, zeatin riboside, and a substance(s) the migration of which is correlated with the Rf interval that included the positions of N6-(Δ2-isopentenyl) adenine and its riboside. A third type of cytokinin, the mobility of which differs from those of the cytokinin standards used, was also produced by T. deformans. The total cytokinin activity in cultures of T. cerasi was calculated to be about 2 μg kinetin-equivalents per liter of culture medium, and the amount released by T. deformans was about 4 μg kinetin-equivalents per liter of medium.
The role of gibberellin and the hulls in the control of germination in Aegilops Kotschyi caryopses
Authors: Wurzburger Judith , Leshem Y. , Koller D.
Published: September 2008

Large and small Aegilops Kotschyi caryopses have low α-amylase activity. After imbibition in water a marked increase takes place in α-amylase activity in the large, hulled and dehulled caryopses and only a slight increase in the small ones. Exogenously applied gibberellic acid (GA3) enhances α-amylase activity in both caryopses, and also improves germination of the small, hulled caryopses.Removing parts of the hull from different sites on the palea or lemma of the small caryopses improves germination. The most pronounced effect was obtained when the segment was removed from the palea just above the embryo. When this excised site was covered with a strip of wet filter paper before germination, the resulting germination was essentially similar to that of the non-excised controls.The role of GA3 and seed coat in improving germination of small Aegilops caryopses is discussed.
The fine structure of the marine chrysophycean alga Phaeosaccion collinsii
Authors: Chen L. C-M. , McLachlan J. , Craigie J. S.
Published: September 2008

An electron microscope examination of Phaeosaccion collinsii has revealed characteristic heterokont structures. Certain features such as penetration of the pyrenoid by a thylakoid suggest that this species should be included in the Chrysophyceae. Fine-structural features thus corroborate previous conclusions based on morphological and chemical investigations.
A detailed study of the genus Azollopsis
Authors: Sweet A. R. , Hills L. V.
Published: September 2008

Five species of Azollopsis Hall, 1968, are described from strata of Campanian to Paleocene age. The spores were recovered from the Belly River and Edmonton Groups of central Alberta, Canada.The genus Azollopsis is emended to include forms with circinate glochidia. Two subgenera, Spiralopsis subg. nov. and Azollopsis subg. nov., are erected to encompass the seven known species of Azollopsis. Two new species, Azollopsis pusilla and A. intermedia, are described, and enlarged descriptions are given for A. tomentosa Hall, 1968, A. coccoides Hall, 1968, and A. pilata (Snead 1969) comb. nov. Salvinia spinata Hall and Bergad, 1971, is formally transferred to Azollopsis (Spiralopsis).A possible ancestral relationship between Azollopsis and Ariadnaesporites Potonié, 1956, emend. Tschudy, 1966, is proposed. The phylogenetic relationships between the species of Azollopsis are discussed.
The psilopezioid fungi. V. Miladina lechithina
Authors: Pfister Donald H. , Korf Richard P.
Published: September 2008

A description and illustrations of Miladina lechithina are provided. This common, yellow, north temperate psilopezioid species has previously been referred to as Peziza lechithina. It is considered to belong to the Pyronemataceae, tribe Aleurieae.
Cyathus crispus, a new species from Ghana
Authors: Brodie Harold J.
Published: September 2008

Cyathus crispus sp. nov. from Ghana has golden-colored, strongly plicate peridia covered externally by curls of hyphal hairs. The small dark brown peridioles are radiately wrinkled; they are provided with a two-layered cortex and long narrow basidiospores. The new species is most closely related to C. limbatus Tul.
Taxonomy of the genus Ceratocystis in Manitoba
Authors: Olchowecki A. , Reid James
Published: September 2008

From Manitoba hardwoods and conifers, 183 collections were examined for Ceratocystis species. Most previously described species, including many type specimens, were also examined.Among the morphological characters used to separate species of Ceratocystis, those of the ascospores are the most reliable and were given major stress herein. The nature of the conidial state, which is distinctive in some species and of diagnostic value in others, was also considered in preparing species diagnosis, and the method of conidium formation was therefore also stressed.The genus Ceratocystis is organized into four groups based mainly on ascospore characters: (1) the Minuta group; (2) the Ips group; (3) the Fimbriata group; and (4) the Pilifera group. It is felt that such groupings reflect the affinities between various species. A key to the groups of species and keys to the species of each of the four respective groups are provided. The keys include 70 species, 50 of which are found in Manitoba.
The systematics of Ranunculus gmelinii and R. hyperboreus in North America
Authors: Scott Peter J.
Published: September 2008

A consideration of the taxonomy of Ranunculus gmelinii DC. and R. hyperboreus Rottb. is presented. The role of phenotypic plasticity is indicated as a factor contributing to the range of morphological variation in these species and to the confusion found in their taxonomy. The present work, by a reexamination of representative material collected throughout the North American range of the species, and the use of controlled growth conditions, has suggested new limits for the species. This has resulted in modifications of the descriptions of the species and (or) the reduction of taxa to synonymy.Ranunculus hyperboreus Rottb. var. turquetilianus Polunin has been made a synonym of R. gmelinii DC.; R. natans C.A. Mey. var. intertextus (Greene) L. Benson has been made a synonym of R. hyperboreus Rottb.
Rest in the cambium of Abies balsamea
Authors: Little C. H. A. , Bonga J. M.
Published: September 2008

Cuttings were collected from the field between September and May, when buds and cambia are dormant, and were placed under favorable conditions in environmental cabinets. Radial width of new xylem, measured at the midpoint of the cuttings, was used to indicate cambial activity.In bud-bearing cuttings, cambial activity was associated with bud activity. Debudding decreased cambial growth. Application of a mixture of indole-3-acetic acid (IAA) and lanolin to the apex of debudded cuttings promoted cambial activity in a manner similar to that effected by expanding buds. Clearly, bud-produced auxin is required for cambial activity in balsam fir.Cambial activity increased with increasing preexposure to natural chilling until about December; thereafter additional preexposure did not further increase cambial growth. Extending the natural chilling period with a period of artificial chilling enhanced cambial growth in material collected during the autumn, but not in material collected later. The effect of chilling was manifested whether or not buds were present during the chilling period. Long photoperiod partly compensated for lack of chilling in autumn-collected material. It is concluded that the cambium of balsam fir in central New Brunswick has an autumnal rest period that grades into quiescence by about December. Cambial rest was not broken by applications of IAA, gibberellic acid, or kinetin, or by IAA with either of the others.
The growth behavior, ecology, and geography of Erythronium americanum in northeast North America
Authors: Holland P. G.
Published: September 2008

During the spring months, 20%, on average, of the non-flowering bulbs of Erythronium americanum Ker. propagate by runners, yet in 2.5 ha of deciduous forest vegetation on heterogeneous terrain at Mont St. Hilaire, Quebec, the plant is either absent from or rare in places with standing water in April–May and on slopes steeper than 15°. Elsewhere in the stand, and particularly on ledges across the back slope and on the blowdown mounds of low gravel terraces, the plant is locally abundant. Field transplant experiments confirmed that the plant neither survives for long nor reproduces vegetatively outside its local range. Also, during five consecutive years of observation on the flora of sample quadrats in the stand, both the number of individuals of this species and their distribution did not significantly change, suggesting that the plant now occupies all suitable niches in the small study area. This may not be true elsewhere in southeastern Canada, where E. americanum is concentrated along the principal plant migration routes from the U.S.A. The plant occupies a much narrower range of topographic situations in Canada than in the U.S.A. and there are grounds for believing it could still be moving into valley bottom areas with a cover of hardwood forest vegetation in eastern and southern Nova Scotia, New Brunswick, the southern Laurentians, and extreme southwestern Ontario.
Revisions for the Bray and Curtis ordination
Authors: Orlóci László
Published: September 2008

The revisions suggested remove from the Bray and Curtis method certain unwanted inconsistencies while retaining the use of freely chosen ordination poles. The revised method performs metric scaling on oblique axes.
Cytotaxonomic studies of Draba nivalis and its close allies in Canada and Alaska
Authors: Mulligan Gerald A.
Published: September 2008

The cytotaxonomy of seven closely related species of Draba is discussed and a key is given. The species are as follows: D. fladnizensis Wulfen (n = 8); D. lactea Adams (n = 24); D. lonchocarpa Rydberg (n = 8); D. nivalis Liljebl (n = 8); D. palanderiana Kjellman (n = ?); D. porsildii G. A. Mulligan, sp. nov. (n = 16); and D. subcapitata Simmons (n = 8). Characteristics of sterile artificial and of natural hybrids, between some of these species and between them and other species of Draba, are discussed. Draba fladnizensis, D. lonchocarpa, and D. nivalis are diploids, each with two homologous sets of eight chromosomes that are partly homologous with sets of the other two species. Draba porsildii contains two sets of 16 chromosomes, each with two completely homologous genomes, and each genome from both sets of 16 is partly homologous with either of the genomes in the other set. All four genomes of D. porsildii are partly homologous with each genome of D. fladnizensis, D. lonchocarpa, and D. nivalis.
Soil microfungi associated with aspen in Saskatchewan: synecology and quantitative analysis
Authors: Morrall R. A. A.
Published: September 2008

The soil microfungi associated with 26 communities of aspen (Populus tremuloides) in Saskatchewan were investigated using a dilution plate technique. Frequency values for the taxonomic entities isolated were calculated, based on occurrence at six sampling sites in each community. Most of the entities were quantitatively rare. The frequency values of the 51 commonest entities were used for quantitative analysis of microfungal community relationships by principal components analysis and by agglomerative classification. These analyses demonstrated only limited correlations of microfungal community structure and species performance with the edaphic and vegetational factors studied. The microfungal communities of aspen stands in the boreal forest region of Saskatchewan appeared to be a distinctive group characterized by the abundance of Mortierella spp. The remaining communities, from all other parts of the province, were distinct from the boreal communities but did not form other discrete groups. Many of them contained a substantial number of species which are common grassland soil microfungi, such as Fusarium spp. Almost all the common species found in aspen soils in this study have been reported previously from soil.
Carbon monoxide fixation by plants
Authors: Bidwell R. G. S. , Bebee Gail P.
Published: September 2008

Leaves of 35 species of temperate and tropical plants absorbed CO in light from air containing 6 ppm CO at an average rate of 0.19 μl/h g fresh weight. CO absorption was measured by the uptake of 14CO from a closed flowing gas system. CO uptake by bean leaves varied considerably with age. Uptake by nine species having widely different rates of absorption was exactly proportional to CO concentration in the range 0 to 100 ppm CO. Absorbed CO was metabolized either by oxidation to CO2 and fixation as such or by reduction and incorporation into serine. Corn, a C4 plant, emphasized the former pathway and bean, a C3 plant, emphasized the latter pathway. CO had various effects on the photosynthesis of leaves of different species; ranging from being inhibitory at concentrations as low as 65 ppm to exerting no influence, or even permitting an increase in net CO2 fixation at 99% CO because of the absence of O2.Plants do not contribute significantly to the global CO balance because their uptake rate is low at the CO concentration normally encountered in interurban areas. However, their contribution may become very important in or near urban and polluted areas, where elevated CO concentrations are frequently found.
Echinopodospora spinosa from Nigerian soils
Authors: Huang L. H.
Published: September 2008

By an ethanol treatment isolation method, Echinopodospora spinosa (Cailleux) Malloch & Cain has been found in subsurface soil from eight different localities in Nigeria. The fungus is characterized by its wide, club-shaped asci and spiny, appendaged ascospores. This is the first report of the occurrence of E. spinosa from soil.
Element content of moss sporophytes: Buxbaumia aphylla
Authors: Hancock James A. , Brassard Guy R.
Published: September 2008

The mineral element content of plant tissues and substrate of Buxbaumia aphylla was analyzed and represents the first data for bryophyte sporophytes. There is no apparent 'barrier' preventing the normal movement of elements from the gametophyte into the sporophyte. Silver, previously found only in Polytrichum and Atrichum, was found in Buxbaumia.
Biosystematics of the genus Populus. III. Naturally occurring Manitoba hybrids of introduced P. × petrowskyana with native P. deltoides var. occidentalis and P. balsamifera
Authors: Ronald W. G. , Steele J. W.
Published: September 2008

Collections of hybrid poplars made in the Roseisle area of Manitoba appear to have resulted from hybridization of introduced P. × petrowskyana Schneid. with native P. deltoides Marsh. var. occidentalis Rydb. and P. balsamifera L. This interpretation was supported by morphology of an open-pollinated seedling population of P. × petrowskyana and by chromatographic analyses. Gas chromatographic results were effective in distinguishing the three parent species; however, the hybrid nature of P. × petrowskyana made chromatographic documentation of hybridization very difficult. High fertility, indicated by abundant production of sound seed, was noted for several mature P. × petrowskyana × P. deltoides var. occidentalis female trees. No barriers were found that would prevent a three species complex of all three hybridizing species.
Reassessment of Tympanis based on types of ascospore germination within asci
Authors: Ouellette G. B. , Pirozynski K. A.
Published: September 2008

The genus Tympanis is reassessed in the light of criteria provided by characters of ascospores and patterns of their germination within asci, rather than classical criteria of host specificity and dimensions of apothecia, asci, and ascospores. Consequently, several taxonomic and nomenclatural changes were made, and included establishment of Tympanis neopithya sp. nov. replacing T. pithya auct. non Karst.; T. pulchella sp. nov. and T. pseudoalnea sp. nov. segregated from T. alnea sensu Groves; T. heteromorpha sp. nov., from T. saligna; and T. grovesii sp. nov., from T. fasciculata; and establishment of T. alpina sp. nov. Tympanis pseudotsugae Groves is transferred to Claussenomyces and a new species, C. luteoviridis Ouellette & Korf, is described.
Ontogeny of spore markings on aeciospores of Cronartium comandrae and peridermioid teliospores of Endocronartium harknessii
Authors: Henderson D. M. , Hiratsuka Yasuyuki
Published: September 2008

Aeciospores of Cronartium comandrae Pk. and peridermioid teliospores of Endocronartium harknessii (J. P. Moore) Y. Hiratsuka were studied under the transmission electron microscope. Spores are ornamented by growth of hyaline structures within a growing primary cell wall. The ornamentation is subsequently exposed by the removal of the primary wall matrix, presumably by reabsorption.
Studies on lichen-dominated systems. VIII. The instrumentation of a raised-beach ridge for temperature and wind speed measurements
Authors: Field G. , Larson D. W. , Kershaw K. A.
Published: September 2008

The instrumentation of a research site on a raised-beach ridge, 5 km inland from Hudson Bay, is described. Fine thermocouples and hot-film anemometers were used to measure air and thallus temperature, and wind speeds, respectively. Replicate sensors were monitored through automatic stepping switches of new design and strip chart recorders. The circuit diagram of the stepping switch is described. The satisfactory operation of the entire system indicates that it is not difficult to maintain this type of electronic equipment in remote sites and opens up considerable possibilities for ecological work in fairly inaccessible areas.
Studies on lichen-dominated systems. IX. Topographic influences on microclimate and species distribution
Authors: Kershaw K. A. , Larson D. W.
Published: September 2008

The marked positional relationship of two plant associations dominated by Cladina alpestris and Alectoria nitidula, occurring on lower ridge slopes and exposed ridge summits, respectively, is described. Measurements obtained under conditions of diffuse radiation over the ridge profile show a consistent trend of slower rates of evaporation over the Cladina alpestris association coupled with lower wind speeds and higher temperatures. Conversely, the relative drying rate of Alectoria nitidula on the ridgetop is much faster with higher wind speeds and lower temperatures. Examination of the metabolic response of these two lichen species to the level of thallus saturation and temperature shows an exact correlation with their spatial distribution in the field and the microclimate at these zones.
The induction of excessive amounts of secondary growth in the petioles of Norway maple (Acer platanoides)
Authors: Weidlich W. H.
Published: September 2008

A fascicular and an interfascicular cambium are present in the petioles of Norway maple. These cambia are capable of producing secondary tissue in excess of that found in intact petioles when petioles are used in a bridge graft.
Effect of temperature pretreatment of achenes of Senecio serra on germination during stratification
Authors: McDonough W. T.
Published: September 2008

Imbibed achenes of Senecio serra Hook., a forb common to high-elevation rangeland in Utah, were stratified at 1C for 20 weeks, with or without temperature pretreatments in the 30–10C range. The temperature pretreatments increased the rates of germination during stratification. The results are discussed in terms of advantageous effects of early germination under a snow cover that normally persists through May.