bluuebunny/crossref_metadata_2025 huggingface dataset:
Shoot responses of young red pine to watering applied over two seasons
Authors: Clements John R.
Published: September 2008

Young red pine (Pinus resinosa Ait.) trees were grown under three watering treatments from late summer until early fall and under two watering treatments again the next spring. Size of apical buds, date of bud swell and bud burst in the spring, number of needle fascicles on the new shoots, shoot length, and needle-fascicle spacing were related to the first treatments. Most of these plant responses were correlated with bud size, and the correlations were unaffected by the spring watering treatments. The effect of treatments was on magnitude only, i.e. on mean sizes or mean numbers of the plant organs.In all cases in this experiment watering treatments during elongation had no effect on the results. Therefore in a species such as red pine, with determinate height growth, environment during bud formation played an important role in determining later shoot responses by acting on the bud size.Possibly the relationships reported here are genetically characteristic, unalterable by environment or at least by water alone. In this case the effect of environment on the trees was a proportionate increase or decrease in the size or number of plant organs.
Coniochaeta velutina and its synonyms
Authors: Taylor L. David
Published: September 2008

An expanded description of Coniochaeta velutina (Fuckel) Munk is presented. Type studies of Rosellinia velutina Fuckel and Rosellinia kellermanni Ellis & Everh. show synonymy. Collections and isolations of a fungus previously identified as Sordaria minima Sacc. & Speg. are referred to C. velutina. Lignicolous, coprophilous, and terrestrial habits of C. velutina are recorded.
Some morphological and physiological effects of palladium on Kentucky bluegrass
Authors: Benedict W. G.
Published: September 2008

Palladium (PdCl2) added to nutrient solution at concentrations greater than 3 mg/l inhibited transpiration of Kentucky bluegrass (Poa protensis L.). In contrast, toxicity only became apparent at 10 mg/l. The effects of palladium included aberrant stomatal histogenesis, inhibition of nodal meristem development, changes in chloroplast structure, and hypertrophy of mesophyll cells, nuclei, and nucleoli. The stomatal aberrations involved accessory cell disorientation which resulted in guard cells not being open to the atmosphere.
Effect of sugars on amino acid biosynthesis in maize root tips
Authors: Oaks Ann , Johnson F. J.
Published: September 2008

There is a general increase in incorporation of acetate carbon when excised maize root tips are aged for 3 h in a salts medium, but little further increase during a subsequent 3-h period. Addition of glucose or sucrose to the medium causes a further increase in the incorporation of acetate carbon into glutamic acid, glutamine, γ-amino butyric acid and into the protein amino acids, principal among these being glutamic, aspartic, proline, threonine, valine and the leucines. Sugars also cause a reduced incorporation of acetate carbon into asparagine. The results indicate that glucose (or sucrose) has a major effect in diverting carbon of the tricarboxylic acid cycle into glutamine and protein amino acids and away from asparagine.
Growth rates in the articulated coralline Calliarthron (Rhodophyta)
Authors: Johansen H. William , Austin Lloyd F.
Published: September 2008

Specimens of the articulated coralline alga Calliarthron tuberculosum growing on an underwater reef off the coast of central California were photographed over a period of 2 years, during which time the mean increase in branch length was 1.7 mm per month. A tier of medullary cells 50–75 μ high is formed about once a day and flexible genicula develop every 1.5–2.7 months. Mean growth rates are 1.3 mm per month in summer (April–Sept.) and 2.3 mm per month in winter (Oct–March). On glass and plexiglass settling surfaces placed among the algae, basal crusts under 1 mm in diameter were visible in less than 1 month, fronds were evident after 2 months, and the fronds bore conceptacles after 11 months. Measurements of photographed and collected specimens reveal that the plants mostly branch during two different times of the year, from March to June and again from September to December.
Development in vitro of excised flower primordia of Nicotiana tabacum
Authors: Hicks G. S. , Sussex I. M.
Published: September 2008

Young flower primordia of Nicotiana tabacum 'Wisconsin 38' have been successfully cultured on a nutrient medium supplemented with kinetin. The petal, stamen, and carpel primordia form in the normal acropetal sequence during the first week on excised floral apices which initially bore only sepal primordia. Relatively normal morphogenesis of the organs ensues, and on optimal concentrations of kinetin, pedicel length, calyx length and width, corolla width, and ovary length and width after 4 weeks were comparable to those in the normal flower at anthesis. The corolla, filaments, and style were always much shorter than normal. Large quantities of pollen were produced on low kinetin concentrations and normal embryo sacs formed in the numerous ovules. When kinetin was omitted from the medium, similar explants initiated all the organ primordia, but these subsequently remained minute through 4 weeks of culture. The data indicate that organ initiation is independent of exogenously supplied hormones, but that the later phases of bud growth have a marked requirement for kinetin. It is suggested that the sepals or petals may provide some stimulus for the initiation of meiosis in the anthers and ovules. In that flower morphogenesis in culture is independent of specific regulation from the rest of the plant, bud development appears to be relatively autonomous.
Reproduction and reproductive irregularities of Abies lasiocarpa and A. grandis
Authors: Eis S.
Published: September 2008

The initiation of potentially reproductive buds, microsporangiate and megasporangiate, takes place annually and is probably independent of environmental factors. Subsequent development is controlled by year-to-year environmental variation and ultimately determines the presence or absence of the buds. Determination of sexual or vegetative function of the buds is a gradual process during which the function may change. Abortion may take place at any time before the function of the bud is determined as well as during the development of reproductive structures.
Influence of genotype and soil on root fan structures of Acer rubrum
Authors: Medve Richard J.
Published: September 2008

Soils collected from eight different plant communities that contained red maples (Acer rubrum L.) had little effect on root fan structures of red maple seedlings. Seedlings from eight seed sources, grown in the same soil types, showed a significant amount of variation for third order root characteristics. Root fan structures, especially those characteristics relating to beaded rootlets, were significantly affected by soil sterilization. Root fan structures were more copious and developed more rapidly on indigenous seedlings than on seedlings grown under greenhouse conditions.
Sources of oat crown rust resistance in hexaploid and tetraploid wild oats in Israel
Authors: Dinoor A.
Published: September 2008

A wealth of resistant plants was found in the tetraploid wild oat Avena barbata Pott, as well as in the hexaploid A. sterilis L. The appreciably high frequency of resistance found in A. sterilis (about 7.5%) reveals an abundant and useful source of resistance, for direct crosses with cultivated varieties. The most efficient procedure of seed collection and screening for obtaining sources of resistance, was (1) random sampling of small samples in the entire region (method A); (2) seedling tests in the greenhouse; (3) construction of distribution maps of resistance; (4) more intensive search in promising locations according to distribution maps (methods B and D). The use of seedling resistance as an indication of adult resistance may result in overlooking the adult plant resistance in up to 40% of the locations where adult resistance could have been found by direct adult tests. Nevertheless, the frequency of locations where plants were found to be resistant in both seedling and adult stages allows for the more convenient use of seedling tests in initial screening.
The cytology and development of Preussia flanaganii sp. nov.
Authors: Boylan Brendan V.
Published: September 2008

The life cycle of Preussia flanaganii Boylan sp. nov. is demonstrated. The ascocarp develops as a result of hyphal fusion and the subsequent proliferation of pseudoparenchyma at the fusion site. The ascocarp is uniloculate or multiloculate and non-ostiolate. The fungus has no known asexual phase and is homothallic. The nuclear cycle in the asci follows a pattern similar to that found in other Euascomycetes. The chromosome number is about 14.
Conformation of chloroplast DNA in wheat leaves
Authors: Mache Regis , Waygood E. R.
Published: September 2008

Sedimentation and electron microscopic studies have provided no evidence for the presence of circular DNA (deoxyribonucleic acid) in chloroplasts from wheat leaves. Electron microscopy of osmotically disrupted chloroplasts has revealed the presence of linear duplex filaments, some with a tertiary helicoidal configuration and possibly monostranded filaments. None of these structures was observed if the chloroplasts were previously treated with DNase (deoxyribonuclease), but the tertiary configuration was somewhat disorganized by RNase (ribonuclease).
Fire blight resistance in Pyrus: hydroquinone formation as related to antibiotic activity
Authors: Hildebrand D. C.
Published: September 2008

Aqueous extracts of pear leaf blade and woody tissues, which are fire blight resistant, exhibited greater antibiotic activity than did extracts of petioles and leaf midribs, and bark, which are susceptible. Increases in antibiotic activity with incubation time were associated with increases in the amount of hydroquinone formed and a concurrent decrease in arbutin. Largest increases in antibiotic activity occurred in extracts of tissues which exhibited the greatest amount of antibiosis in the tissue bioassay test. The levels of other phenolics did not change significantly, even when tissue fragments were present in the extracts. Leaf age did not appreciably affect the diffusion from leaf discs of compounds necessary for antibiotic activity. β-Glucosidase was not inactivated in leaf discs thawed for long periods. There is an insufficient amount of free hydroquinone in Pyrus tissues to affect antibiotic activity or fire blight resistance. Free hydroquinone occurs in large amounts in extracts obtained with hot methanol. These findings continue to support the validity of tissue bioassay as a method for measuring the relative β-glucosidase activity in Pyrus tissues.
Chromosome pairing and fertility in Spartina × caespitosa
Authors: Marchant C. J.
Published: September 2008

A detailed study of meiosis and breeding behavior of Spartina × caespitosa (A. A. Eaton) Fern, and a comparison with S. patens (Ait.) Muhl. and S. pectinata Link, its putative parents, has revealed regular meiotic pairing, relatively high pollen stainability, and a low seed set in the hybrid when intercrossed with other clones of S. × caespitosa or with S. patens and S. pectinata. S. × caespitosa quite frequently occurs and persists under competition amidst juxtaposed clones of rhizomatous S. patens and S. pectinata but there is little evidence of an F2 generation in the wild and it maintains a very localized distribution. Many characteristics of S. × caespitosa are closely similar to those of a species and features of hybrid nature are not easy to define.
Observations on the fine structure of Oedogonium. VI. The striated component of the compound flagellar "roots" of O. cardiacum
Authors: Hoffman Larry R.
Published: September 2008

The striated, inner component of the compound flagellar "roots" of zoospores and spermatozoids of Oedogonium cardiacum has been studied ultrastructurally after three methods of preparation. The roots constitute an element of the ring-shaped flagellar apparatus, with the roots and basal bodies alternating in equal numbers. Each root consists of two components radially superposed; the outer component is ribbon-like and formed of three parallel microtubular elements, while the inner component is rod-like (tapering at each extremity) and demonstrates a very regular pattern of cross-striation. Although the striated pattern in sectioned roots differed somewhat from the pattern obtained with negatively stained roots, the major periodicity in both instances averaged about 305–325 Å. This contrasts to a periodicity of 150 Å which was reported earlier. The pattern of cross-striation appears the same for roots of both spermatozoids and zoospores when any one method of preparing the material is considered separately. Furthermore, no distinctions were observed in zoospore roots obtained from a haploid male strain, a haploid female strain, and a diploid female strain. The striated root component of Oedogonium may provide mechanical support for the flagellar apparatus, thereby serving as a means for distributing throughout the motile cell the stresses generated by flagellar action. A possible contractile function cannot be excluded.
Absence of lateral transfer within the oat leaf of substances responsible for crown rust resistance
Authors: Burrows V. D.
Published: September 2008

The longitudinal half of each of three inoculated leaves of an unusual trisomic oat seedling was resistant and the other half susceptible to crown rust race 264. Resistance was conditioned by the Pc-15 gene located on the extra M4 chromosome. It is postulated that the chimera resulted early in the ontogeny of the plant and one of the cells which eventually developed into the susceptible half of the plant failed to receive or lost its M4 chromosome. The chimera demonstrates that the factors responsible for crown rust resistance are not mobile, in a lateral direction, within the leaf.
Effect of 60Co gamma irradiation on the survival of some fungi in single samples of each of three different grades of wheat
Authors: Mohyuddin M. , Skoropad W. P.
Published: September 2008

Wheat grains of grades No. 1, 2, 3 Northern were treated with 100, 300, 500, 700, or 1000 krad of 60Co gamma irradiation to study its effect on the fungi present. Species of Alternaria and Fusarium were abundant, and were highly resistant to irradiation in situ, requiring 1000 krad for complete inactivation. Species of Aspergillus, Rhizopus, and Absidia were less frequently isolated from the grain, and were less resistant to inactivation by irradiation. A dose of 300 krad was required to completely eliminate these fungi. The grade of grain did not effect the survival behavior of various fungi after treatment with gamma irradiation.Increasing doses of gamma irradiation interfered progressively with the formation of septa in the spores of Alternaria sp., and, at a dose of 700 krad, spores failed to form.
Electron microscopy of the sporangium of Phytophthora capsici
Authors: Williams W. T. , Webster R. K.
Published: September 2008

This paper reports results of a study on the ultrastructural cytology of sporangia of Phytophthora capsici Leonian with emphasis on flagellum formation, general sporangial structure during zoospore cleavage, and the presence, structure, and transition of cytoplasmic organelles and inclusions during these processes.Non-cleaving sporangial cytoplasm contains a high concentration of ribosomes, mitochondria, vacuoles, lipid inclusions, and endoplasmic reticular cisternae scattered throughout the cytoplasm. Nuclei in mature sporangia are located at the periphery of the cell, with their narrow poles aligned towards the plasma membrane. The apical papilla measures 4–5 × 10 μ, and is initiated as a fibrous third layer under the two-layered cell wall several microns from the apex. The outer wall layer surrounds the papilla while the inner wall narrows and disappears near the crown. The basal septal plug is a combination of the inner wall layer and slime substances.One of the first structural changes in the cytoplasm during zoospore cleavage is the genesis of the flagellar apparatus. Paired centrioles next to the narrow poles of the nuclei elongate to form kinetosomes which extend through the cytoplasm toward receptive axonemal vesicles. Axonemes then form in the axonemal vesicles. The terminal plate and its prisms account for the appearance of the axoneme when it forms above the terminal plate in the axonemal vesicle. The axonemal cylinder has a typical 9 + 2 morphology and the axonemal sheath is continuous with the axonemal vesicle tonoplast. The nucleus is an integral part of the flagellar apparatus and appears to be connected to the kinetid (axoneme + kinetosome) base via microtubules. Golgi dictyosomes occur in the sporangia during all stages of growth and may be responsible for elaboration of needed membranes during zoospore production. Osmiophilic droplets (liposomes), located within vacuoles, are a predominant feature of precleavage cytoplasm. These globules are probably lipid in nature. As cleavage begins, the liposomes become less opaque at the margins, and striations appear, eventually encompassing all or most of the liposomes at the time of cleavage. The liposomes then become less spherical and expand, filling the vacuoles. Electron-transparent regions eventually appear throughout the liposomes and the vacuolar membrane may disappear.Cleavage of the cytoplasm into zoospores occurs by the alignment and fusion of cleavage vesicles around individual nuclei. During this period organelles migrate to these centers. The cleavage vesicles coalesce with each other and the axonemal membranes, eventually becoming the plasma membranes of the daughter zoospores.
Carbohydrate movement in pea plants in relation to axillary bud growth and vascular development
Authors: Wardlaw Ian F. , Mortimer D. C.
Published: September 2008

The dormant bud in the axil of leaf 4 of pea plants (Pisum sativum cv. Alaska) began to elongate within 4 h of removal of the shoot apex. Within 24 h after decapitation there was an increase in the uptake of 14C-labeled assimilates by the bud, following the assimilation of 14CO2 by the lamina of leaf 4, and an increase in total sugar per bud. Starch was present in the inhibited bud and also increased within 24 h of decapitation. Complete vascular differentiation and the formation of additional xylem elements was not evident until 48 h after decapitation. The localization of soluble sugars in the bud trace, determined by microautoradiographic techniques, suggested that differentiation of the phloem did not greatly precede that of the xylem. This sequence suggests that apical dominance was not acting through inadequate development of the bud vascular system.
The influence of wind on ring width and cell length in conifer stems
Authors: Bannan M. W. , Bindra M.
Published: September 2008

In the three species studied, inequalities were noted in amount of radial growth around the stem. Rings tended to be wider on the east than on the west side. Because the prevailing wind is from the west, the eccentricity is interpreted as being due to wind action. In keeping with the general inverse relationship between ring width and cell length, the cells were longest on the west side where the rings were narrowest. The difference in cell length was not relatable to diversity in frequency of multiplicative divisions in the cambium.
Variation in mating capacities among isolates of Cochliobolus carbonum
Authors: Nelson R. R.
Published: September 2008

Qualitative and quantitative variation in mating capacities among 122 isolates of Cochliobolus carbonum was demonstrated by determining: the qualitative ability of each isolate to cross with isolates of opposite mating type (A–a); the relative frequencies of fertile crosses between specific pairs of compatible isolates; and the number of perithecia, asci, and ascospores produced in different compatible combinations. Marked differences in mating abilities suggest that additional genes influence the ability of paired A × a to cross and (or) govern the resulting extent of cross-fertility. The role of the additional genes as regulators of vital biosynthetic pathways is discussed.
Sexual reproduction and agamospermy in the genus Draba
Authors: Mulligan Gerald A. , Findlay Judy N.
Published: September 2008

Draba oligosperma is primarily apomictic, exhibiting agamospermy over most of its range. Some plants of this species occurring within a small area in Montana are probably sexual. Canadian material of 15 other species of Draba was shown to be selfed automatically and was self-compatible. Evidence was presented to indicate that outcrossing occasionally occurs in these species. It was also suggested that some self-incompatible outcrossing species are found farther south in North America.
Giant cell formation in tomato roots caused by Meloidogyne incognita and Meloidogyne hapla (Nematoda) infection. A light and electron microscope study
Authors: Paulson Ronald E. , Webster John M.
Published: September 2008

Light and electron microscope studies show the changes which occur during transformation of small thin-walled plant cells into greatly enlarged "giant cells," which act as nutrient sources for the developing nematodes. Proliferation of cytoplasm and organelles, lobing of nuclei, and development of irregularly thickened cell walls suggested an increased metabolic activity in these cells. Giant cells appear to be most actively synthesizing materials, including a crystalline form of storage protein, during the later stages of nematode development. Numerous spiny vesicles were present and thought to be associated with the production of storage protein. Shortly after maturation of the female nematode, there was a breakdown of giant cell structure, characterized by a loss of membrane clarity and eventual disappearance of organelles.
Some histochemical changes underlying shoot initiation in tobacco callus cultures
Authors: Thorpe Trevor A. , Murashige Toshio
Published: September 2008

A comparative histochemical study of changes in nucleic acids, proteins, and carbohydrates was performed on freeze-substituted samples of tobacco callus, cultured under shoot-forming and non-organ-forming conditions. The DNA (deoxyribonucleic acid) content per cell showed no apparent change, whereas denser staining for RNA (ribonucleic acid) and protein were observed in shoot-forming regions just before and during the initiation of organized structures. The most dramatic finding was the heavy accumulation of starch in shoot-forming tissue; this accumulation preceded any organ formation and was mainly in regions which ultimately gave rise to primordia.
Detailed morphology, taxonomy, and distribution of Pistillipollenites macgregorii
Authors: Rouse Glenn E. , Srivastava Satish K.
Published: September 2008

Pistillipollenites macgregorii Rouse is redescribed incorporating the detailed morphological characteristics of apertures and exine as seen through the scanning electron microscope. It is proposed that P. macgregorii be restricted to only those triaperturate pollen that have apertures resembling irregular pores in general configuration. Apertures in P. macgregorii appear as circular to elliptically depressed weak areas distributed equatorially. The exine consists of three layers: a foot-layer, baculate-layer, and a tectate-layer that forms large and small primary gemmae. Some primary gemmae bear large and small secondary gemmae. Graphs of size distribution of both Alaskan and Burrard Formation populations show essentially no difference in size. Pistillipollenites appears to be most characteristic of Paleocene and Eocene assemblages that reflect humid, warm temperate to subtropical conditions, and were probably deposited relatively in situ.
Observations on the morphology, anatomy, classification, and reproductive cycle of Saxifraga ferruginea
Authors: Randhawa A. S. , Beamish Katherine I.
Published: September 2008

A survey of morphology and anatomy has been made in the wide-ranging species, Saxifraga ferruginea Graham (Saxifragaceae), of western North America. Anatomical features are reported in detail and are consistent within the six populations studied.The species has been subdivided in many different ways by many taxonomists on the basis of morphological variability. The characteristics previously used and many others have been examined in the present study: leaf and bract size, shape, dentation, and pubescence; petal size and shape; size of pollen grains and stomata; size of seeds and length of tubercles thereon. Special attention has been given to frequency of plantlet production since this is a prime diagnostic feature in existing classifications. The many morphological features examined have all been found to vary so much even within populations that no pattern of subspeciation has appeared.The conclusion is that S. ferruginea should be considered one variable species, there being no stable characters and correlated differences on which to base subcategories. A summary of the reproductive cycle of the species is included.
Carex podocarpa and its allies in North America
Authors: Murray David F.
Published: September 2008

Carex podocarpa R. Br. and five other species in the section Atratae, genus Carex (Cyperaceae), are discussed: C. macrochaeta, C. microchaeta, C. nesophila, C. paysonis, and C. spectabilis. The distinction of phyllopodic and aphyllopodic fertile culms is stressed as a primary dichotomy in this complex. Drawings of perigynia and scales are included for each taxon. A key to species is provided, and a new combination, C. microchaeta ssp. nesophila, is proposed.
Nematophagous Hyphomycetes: observations on Harposporium helicoides
Authors: Barron G. L.
Published: September 2008

The conidia of endoparasitic nematophagous Hyphomycetes ingested by nematodes lodge in either the buccal cavity or the oesophageal lumen. In H. helicoides, however, nematodes have little difficulty in swallowing the conidia, and infection is initiated by the conidia germinating in the gut. The characteristics of H. helicoides in culture are given.
The soil microfungi of white cedar forests in Ontario
Authors: Bhatt G. C.
Published: September 2008

A study was made of the fungal populations of neutral to alkaline organic soils from eastern white cedar (Thuja occidentalis L.) forests in southwestern Ontario. A modified dilution plate technique was used, with peptone–dextrose agar medium supplemented with streptomycin and rose bengal. A total of 184 species belonging to 101 genera were recovered. The dominant species recovered were, in order of dominance: Penicillium spp.; Fusarium spp.; Trichoderma viride; Paecilomyces carneus; Coniothyrium spp.; Cladosporium herbarum; Gliocladium roseum; Cephalosporium spp.; Sterile dark mycelium; Pestalotia sp.; Phialophora spp.; Botryotrichum piluliferum; and Myrothecium roridum. Several undescribed soil fungi were also isolated.
The secondary phloem of Austrobaileya scandens
Authors: Srivastava Lalit M.
Published: September 2008

The origin of sieve elements and parenchyma cells in the secondary phloem of Austrobaileya was studied by use of serial cross sections stained with tannic acid – ferric chloride and lacmoid. In three important respects, Austrobaileya phloem recalls gymnospermous features: it has sieve cells rather than sieve-tube members; a significant proportion of sieve elements and companion cells arise independently of each other; and sieve areas occur between sieve elements and companion cells ontogenetically unrelated to each other. The angiospermous feature includes origin of most sieve elements and parenchyma, including companion cells, after divisions in phloic initials. In these instances companion cells show a closer ontogenetic relationship to sieve elements than do other parenchyma cells. The combination of gymnospermous and angiospermous features makes phloem of Austrobaileya unique when compared to that of all those species that have been investigated in detail. It is further suggested that the term albuminous cells is inappropriate and should be replaced by companion cells but that the ontogenetic relationship implicit in the definition of companion cells is too restrictive and should be abandoned.
Analysis of moss dehydrogenases by polyacrylamide disc electrophoresis
Authors: Taylor I. E. P. , Schofield W. B. , Elliott Anita M.
Published: September 2008

Polyacrylamide disc electrophoresis has been used to separate multiple forms of formic, glutamic, lactic, and malic dehydrogenases from 20 moss species. The enzymes were detected using a tetrazolium procedure. The analyses are the first reports of these enzymes from the Bryophyta.The value of disc electrophoresis for physiological, ecological, and taxonomic studies of mosses is discussed.
Inhibitory compounds of Pinus monticola resistant and susceptible to Cronartium ribicola
Authors: Hoff Raymond J.
Published: September 2008

In a study of the effects of preformed inhibitory compounds in resistant and susceptible western white pine (Pinus monticola Dough), ether fractions from 6 of 16 resistant trees substantially reduced germination of basidiospores of Cronartium ribicola J. C. Fisch. ex Rabenh. as compared to the percentage of germination observed in paired susceptible trees. The foliage of western white pine was found to contain a high level of other inhibitory compounds as well. The implications of these and other findings concerning toxic compounds are discussed.
Distribution of Phytophthora and Pythium species in soils in the Continental United States
Authors: Hendrix, Jr. Floyd F. , Campbell W. A.
Published: September 2008

The Pythium flora of 2132 soil samples from all sections of the United States was determined using an apple trapping method and two selective media. Isolates of the P. irregulare – P. debaryanum complex were obtained from 90% of the samples, and made up 55% of the 10 566 isolates examined. Isolates referable to the P. dissotocum – P. perniciosum complex, P. spinosum, P. splendens, P. ultimum, P. vexans, and heterothallic forms including P. sylvaticum, P. heterothallicum, and P. intermedium were obtained from 5 to 15% of the samples. Pythium afertile, P. aphanidermatum, P. dissotocum – P. perniciosum, P. irregulare – P. debaryanum, P. spinosum, P. torulosum, P. ultimum, and the heterothallic species were found in soil samples from 60% or more of the sections of the country sampled. The following species were isolated infrequently: P. acanthicum – P. oligandrum complex, P. catenulatum, P. helicoides – P. oedochilum complex, P. mamillatum, P. middletoni, P. myriotylum, P. paroecandrum, P. periplocum, P. prolatum, P. pulchrum, P. rostratum, P. vexans, Phytophthora cinnamomi, and P. parasitica.
The life history of Porphyra miniata
Authors: Chen L. C-M. , Edelstein T. , Ogata E. , McLachlan J.
Published: September 2008

The complete life history of the distromatic species Porphyra miniata has been obtained in culture. Conchospores were released from the conchosporangia only at low temperature (~5 °C). These spores formed the leafy thallus of about 1 m in length. After about 4 months the leafy thalli developed α- and β-spores; the former were viable and initiated the life history again. Neutral spores were not observed in specimens either from nature or from culture.
Relation of xylem plugging to black rot lesion development in cabbage
Authors: Sutton John C. , Williams Paul H.
Published: September 2008

Black rot lesion development in cabbage leaves was correlated with accumulation of plugging material in the xylem vessels as Xanthomonas campestris multiplied and spread. Plug formation preceded a partial disorganization of the xylem, and spillage of bacteria from the vessels. The movement of eosin and 32PO43− was blocked within the vessels, and plugs caused water shortage in affected cells. Vein blackening, the first symptom of the disease, occurred after plugs had formed, and was associated with an accumulation of melanins among collapsing cells of the vascular bundle. The population of viable bacteria within the veins declined rapidly as the veins blackened.Advance of the bacteria in the xylem vessels accounted for the relationship between venation and lesion spread. A weakly virulent isolate spread extensively in the xylem vessels if inoculated with a virulent isolate, but not when inoculated alone. Acid mucopolysaccharide plugging material was not formed in vessels infected with the weakly virulent isolate.Water stress in cells of interveinal tissues of inoculated leaves resulted in chlorosis, loss in turgor, and loss of electrolytes. If net water loss from infected leaves was prevented by high atmospheric relative humidity, affected cells remained green and turgid and maintained their electrolyte balance.
Nova Scotian fungi. New and noteworthy Hygrophorus species
Authors: Bird Carolyn J. , Grund Darryl W.
Published: September 2008

This paper considers 12 Hygrophorus species collected in Nova Scotia during 1967–68, stressing differences from previously published descriptions and presenting additional data. Of these, 10 are first records for the province. Four of the 10 are being reported for the first time in Canada, and 2 have been previously collected in Nova Scotia but referred to other species. One species, although previously recorded, is included because of significant differences from earlier accounts. One new species, H. murinus, is described.
Germination patterns in Daucus carota ssp. carota. I. Variations in the 1967 collections
Authors: Dale Hugh M.
Published: September 2008

Wild carrot seeds of 70 provenances were periodically germinated in 1968 and 1969. The number of seeds germinating gave a whole range of values with no apparent groupings. An examination of numbers germinating at various times after imbibition showed that some grouping was possible. Of the seeds which germinated, in some lots up to 99% germinated in week 1, in others up to 48% in week 2, and in some up to 40% did not germinate until given a cold stratification. Three patterns were derived from the germination data for these three time periods by converting percentages of seeds germinating at each time into a percentage of the seeds which eventually germinated during that test. The pattern is related to the time of collection of seed.Seeds were stored dry at 4° up to 22 months with the time stored affecting the number of seeds germinating. Storage had more influence on the total number germinating than on the time of radicle emergence after imbibition. During the initial storage period the total germination was reduced. This was followed by an increase in numbers for several months, and then a gradual decline. These changes in dry storage may be due to changes in the endosperm which clamps the embryo in the seed.
Postdormancy development and growth of microsporangiate and megasporangiate strobili of Abies balsamea
Authors: Powell G. R.
Published: September 2008

Postdormancy development and growth of strobili of Abies balsamea (L.) Mill, are described. Some strobilus growth occurs within the buds before bud swelling becomes detectable. The strobilus buds burst before the vegetative buds. The latter burst about 10 days after the megasporangiate buds, by which time pollen is being shed and the megasporangiate strobili are receptive. Elongation of megasporangiate strobili is divided into two stages; the first, occurring before the strobili are receptive, accompanies the grand period of bract growth; the second accompanies the grand period of ovuliferous-scale growth. The two stages are not evident when growth is expressed as dry weight. Elongation ceases in mid July, but strobilus dry weight increases until mid August. This is largely accounted for by embryo growth in the contained seeds.The moisture content of microsporangiate strobili reaches a maximum just before pollen release. Pollen grains account for about half the mature strobilus dry weight. The moisture content of megasporangiate strobili reaches a maximum at the time of fertilization, after which it declines until the strobili break up.Megasporangiate strobili situated in upper positions become larger than those situated lower in the megasporangiate-strobilus bearing zone.
Developmental morphology of the crustaceous alga Melobesia mediocris
Authors: Lee R. K. S.
Published: September 2008

Thallus development is described in three phases on the basis of structure and ontogeny: (1) spore germination and parenchymatous disc, (2) prostrate filaments, and (3) erect filaments. Also given are detailed analyses of the development of the female reproductive complex of both the conceptacle and procarpic elements; the gonimoblast and carposporangium; and the asexual apparatus made up of roof cap, conceptacle, pore cells, and tetrasporangia. The morphology of mature spermatangia and their conceptacles is described. Certain interpretations, pertaining to structure, ontogeny, or function, differ from those made by previous workers for the same species or others of the Melobesioideae.
Growth of Odontia bicolor in vitro
Authors: Lachance Denis
Published: September 2008

The growth of Odontia bicolor in soil and in balsam fir wood was studied. In steam-sterilized organic soil, the fungus grows rapidly, producing a scanty and uniform growth, whereas in propylene oxide gas-treated or natural organic soil, it forms mycelial strands. In mineral soil, the fungus reacts as in organic soil except that growth is more sparse. The fungus grows through natural soil and colonizes new substrate more rapidly when mycelial strands are linked to an appropriate food base.The optimum temperature for growth on a 2.5% malt extract medium occurs between 22 and 27 °C. The fungus grows well in balsam fir wood at any moisture content above 42% of the oven-dry weight, and twice as fast in sapwood as in heartwood. Its growth is not influenced by previous storage of the wood, either frozen (−20 °C) or at a temperature of 2 °C for up to 16 weeks.
Picea banksii n. sp. Beaufort Formation (Tertiary), northwestern Banks Island, Arctic Canada
Authors: Hills L. V. , Ogilvie R. T.
Published: September 2008

Picea cones of late Tertiary age, from northwestern Banks Island, Arctic Canada, are described and illustrated. Extremely good preservation allowed measurements on cone length and width, scale length and width, seed wing length, and bract length, width, and number of teeth. In addition, ratios such as scale length to width; seed length to width; seed length to scale length; and bract length to scale length are calculated.Comparison is made with extant species of Picea and it is concluded that the fossil is most closely related to Picea glauca. It is suggested that a Picea glauca type was ancestral to many Northern Hemisphere spruce.
Forest microfungi. IV. A leaf spot of Populus caused by Cladosporium subsessile
Authors: Sutton B. C.
Published: September 2008

The binomial Phaeoramularia maculicola (Rom. & Sacc.) n. comb. (≡ Torula maculicola Rom. & Sacc, syn. Cladosporium subsessile Ell. & Barth.) is proposed for a fungus causing leaf lesions on various Populus species in Canada, the United States, and Sweden. The generic relationships of the organism are discussed, a detailed description provided, and an account of the symptoms, host range, and distribution of the disease given. Differences in morphology of the fungus and symptoms of the disease are emphasized in distinguishing this syndrome from the shoot and leaf blight caused by Pollaccia radiosa (Lib.) Bald. & Cif.
Phlyctochytrium reinboldtae (Chytridiales): morphology and physiology
Authors: Barr D. J. S.
Published: September 2008

A pure culture of Phlyctochytrium reinboldtae Persiel isolated from soil near Ottawa, Canada, grew best at 20 and 25 C, slightly at 10 C, and not at all at 35 C. It grew best in alkaline media and required no exogenous vitamins. It used ammonium, nitrate, and nitrite nitrogen and each of the 7 amino acids tested. Of 18 carbon sources, it used glucose, fructose, trehalose, maltose, mannose, cellobiose, glycerol, and starch. It is similar physiologically to P. punctatum Koch and P. plurigibbosum Barr and morphologically to P. papillatum Sparrow and P. dichotomum Umphlett.
A suggested frost injury rating system for clones of trees
Authors: Morsink W. A. G.
Published: September 2008

The author presents a system which relates actual frost injury to an integrated climatic factor for the evaluation of clones of woody plants. This climatic factor combines duration and intensity of normal minimum temperatures below 42 °F, and is referred to as "normal minimum dormant degree days" or M.D.'s. Five grades of frost injury are used to describe a range of frost damage encountered on woody plants.To illustrate the system, a table of frost injury ratings for species native to Ontario has been provided; the frost injury ratings for species are shown for quantities of 1000 M.D.'s, ranging from 3000–9000 M.D.'s. The system permits the expression of differences for one species (or clone) in frost injury ratings for various quantities of M.D.'s. It is suggested that the use of this system could be extended for winter survival prediction of woody plants for specific localities.
Role of surface films in the germination of rust uredospores
Authors: Woodbury William , Stahmann Mark A.
Published: September 2008

An association of rust uredospores with materials which form films on water surfaces was demonstrated. One milligram of spores of Puccinia graminis tritici and 3.5 mg of Uromyces phaseoli spores released about 100 cm2 of film within 1 min of coming into contact with a large water surface. Oxidative reactions within these films, which were accelerated by light, formed products which inhibited spore germination. When spores were germinated on a large volume of water, germination varied with the surface area, which indicated that inhibitor was formed and retained at the water surface.Hydration of spores resulted in an increased germination, a decreased film area and a delay or prevention of film reactions. Storage of spores at lower humidities resulted in decreased germination, decreased film area, and film reactions which began as soon as the spores came into contact with the water surface. These results suggest that the effects of light and of storage conditions on germination may be mediated by surface film materials.The amount of surface film material released by wheat and bean rust spores may be correlated with the wetability of the host cuticle and also with the ability of rusts to differentiate infection structures in vitro on artificial membranes. On plastics which supported the formation of infection structures, spores acquired spherical infection droplets when exposed to a humid atmosphere. The surface area of these droplets was correlated with the area of surface film. It is suggested that surface film material may interact with the appropriate host cuticle to determine the size and configuration of infection droplets. This would provide a water surface of defined area upon which film reactions occur resulting in a sequence of products which control germination, directed growth of the germ tube and differentiation of infection structures.
Experiments and observations on the aftereffect of wilting on stomata of Rumex sanguineus
Authors: Allaway W. G. , Mansfield T. A.
Published: September 2008

Stomata of Rumex sanguineus showed an aftereffect of wilting, those of previously wilted plants failing to open as widely as usual. The water content of previously wilted leaves recovered rapidly after watering. The wilting treatment killed about 2% of the guard cells, and was followed by a persistent 5.5 to 7% increase in the carbon dioxide compensation point of leaves. Replacing the air in the intercellular spaces with carbon-dioxide-free air did not remove the aftereffect of wilting on the stomata. Detached leaves also showed the aftereffect, although it was apparently smaller than in leaves attached to the plant. Neither persistent water deficits, nor killing of guard cells, nor increased intercellular space carbon dioxide concentration could explain the aftereffect of wilting on stomata. The results are, however, consistent with the view that an inhibitor of stomatal opening accumulates in leaves after a period of water stress or, alternatively, that there is a deficiency of a substance which promotes opening.
The automation and standardization of certain herbarium procedures
Authors: Beschel R. E. , Soper J. H.
Published: September 2008

This paper presents a brief review of recent developments in the fields of data processing and computer applications as related to herbarium procedures, indicates some of the benefits to be derived from the automation of certain routine operations in the herbarium, and suggests how data presented on herbarium labels might be improved and made more suitable for their preparation as input to information retrieval systems.
The effect of anionic and nonionic detergents on soil microfungi
Authors: Lee Benny K. H.
Published: September 2008

Surveys of the microfungal populations in potting soil watered with tap water, a solution of anionic 15-S-3A detergent (Tergitol, 15-S-3A), and a solution of nonionic 15-S-9 detergent (Tergitol, 15-S-9), revealed a greater reduction in propagule densities in the anionic detergent watered soil than in the nonionic detergent watered soil. In the anionic detergent study, 39 species, including six dominant species which contributed 58% of the isolates, were obtained from the treated soil. In the nonionic detergent study, both sample populations contained 29 species and the four to six dominants contributed 67–68% of the 100 isolates.Twenty-two isolates representing 10 dominant species were tested in vitro for sensitivity to the two detergents. All grew at the lowest concentration (10 p.p.m.) of both detergents. The growth rates of nine isolates increased with the addition of 10 p.p.m. of the anionic detergent; four isolates showed increased growth with 10 p.p.m. of the nonionic detergent. With increasing concentration of detergent from 100 to 1000 p.p.m., the growth rates of 21 of the 22 fungi decreased. Isolates recovered from detergent-treated soil grew better in the medium containing detergent than the same species recovered from the control soil. In concentrations of 1000 p.p.m., complete inhibition was displayed by four species in the anionic series compared to five species in the nonionic series. Both detergents affected pigmentation, exudate formation, and rigidity of the sporangiophore in several of the fungi.Fourteen of the 16 isolates tested used anionic detergent and 12 isolates used nonionic detergent as a carbon source for growth. Dry weight differences indicated that the anionic detergent was more available than the nonionic detergent.
Plant species diversity in a woodland–meadow ecotone near Regina, Saskatchewan
Authors: Jones Gweneth J. , Peterson Everett B.
Published: September 2008

A 60-meter-wide ecotone between Populus woodland and Scirpus–Juncus–Calamagrostis meadow on a former lakeshore in southern Saskatchewan was characterized by the following features in relation to the adjacent woodland and adjacent meadow: intermediate elevation; intermediate depths to water table; maximum snow accumulation and maximum snow persistence in the spring; maximum plant species diversity; maximum variety of growth forms (trees, shrubs, and herbaceous species); maximum surface accumulation of L and F organic layers.
Variation in the spectral qualities of flowers in the Nymphoides indica complex (Menyanthaceae) and its possible adaptive significance
Authors: Ornduff Robert , Mosquin Theodore
Published: September 2008

The Nymphoides indica complex is polymorphic in the spectral qualities of its flowers. Flowers of the circumtropical white-flowered race absorb ultraviolet light strongly. Flowers of yellow-flowered South African plants reflect almost uniformly, but those of yellow-flowered plants from the West Indies absorb more strongly in the center and reflect from the remaining portion of the petals. The evolution of these contrasting patterns is considered to represent an increasing specialization of pollinator–flower relationships because of the effect these patterns have in directing pollinating insects to the flowers and to the reproductive organs of the flower.