bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon dioxide and oxygen concentrations in relation to survival and saprophytic growth of Pythium irregulare and Pythium vexans in soil
Authors: Gardner Donald E. , Hendrix Jr. Floyd F.
Published: September 2008

In both pasteurized and nonpasteurized soils, higher CO2 combined with normal atmospheric O2 concentrations were generally favorable for growth and survival in comparison with the effects of lower O2 combined with atmospheric CO2 concentrations. Different amounts of growth among the various gas treatments and between pasteurized and nonpasteurized soils also occurred in the general populations of soil fungi, actinomycetes, and bacteria. Gas effects on total fungi, actinomycetes, and bacteria may have resulted in indirect effects on Pythium.
Initiation of floral organs in Nicotiana tabacum
Authors: Hicks G. S.
Published: September 2008

Floral buds of Nicotiana tabacum were fixed, sectioned, and stained by routine procedures, then analyzed microscopically. Initiation and emergence of all four classes of floral organs involved periclinal division in the second tunica layer (T2) and division of corpus cells. The extent of periclinal T2 divisions was different in different organs. Plasmolysis of tunica and corpus cells was observed at organ sites. The results generally parallel those of other studies.
Fine structure of Wolffia arrhiza
Authors: Anderson J. L. , Thomson W. W. , Swader J. A.
Published: September 2008

Light and electron microscopic studies of Wolffia arrhiza L. frond development during vegetative reproduction showed that the fronds were composed entirely of chlorenchymous cells. Chloroplasts in the epidermal cells other than the guard cells were unique in that they contained no starch. Cell division occurred only at the proximal end of daughter fronds early in their development. Meristematic cells contained chloroplasts with clearly defined grana. Proplastids, commonly observed in meristematic cells of apical regions of other plants, were absent in the cells of these plants.
The reciprocating flow hypothesis of translocation in plants
Authors: Miller D. M.
Published: September 2008

The purpose of this communication is to show that phloem transport could result as readily from a reciprocating movement of the sieve tube sap as from a mass flow in one direction. Furthermore such movement would not lead to the terminal buildup of substances to which the sieve tube membrane has little permeability nor would it have difficulty in explaining either transport of different substances at different rates or bidirectional transport within the same tube. A kinetic analysis of this mechanism predicts that the concentration profiles of moving solutes would correspond in general with those reported in the literature, including those obtained after short intervals in single fibers. These latter experiments suggest that if such oscillations occur, they do so with a displacement of the order of a centimeter and a period of the order of a minute. Oscillations of a similar magnitude are found during a protoplasmic streaming in the mold Physarum polycephalum, which supports a previous suggestion that protoplasmic streaming together with some osmotically driven mass flow might be responsible for phloem transport.
Taxonomic studies of North American Sparganium. I. S. hyperboreum and S. minimum
Authors: Harms Vernon L.
Published: September 2008

The taxonomy of the two similar species Sparganium hyperboreum and S. minimum in North America is investigated by a morphological analysis of herbarium specimens and the construction of hybrid indices. It is concluded that despite some hybridization and apparent introgression the two taxa should be recognized as specifically distinct. The criteria for their separation are presented.
Tissue volume changes in black spruce phloem
Authors: Brudermann G. , Koran Z.
Published: September 2008

Cell dimensions and volume changes were studied in black spruce phloem by microscopic techniques.It was found that sieve cells measure 4 mm in length and 30 μm in diameter and constitute on the average 52.2% of the volume of the inner bark. However, sieve cell volume decreases gradually from 62.8% at the cambium to 38.7% in the outer dead phloem as a result of the collapse of these elements. In contrast, the volume of longitudinal parenchyma increases from 28.7% at the cambium to 43.7% in the outer dead bark.Sclereids possessing thick and multilayered walls make up on the average 3.4% of the inner bark. Sclereid volume increases from 2.8% at the cambium to 9.6% in the outer bark. On the average, rays constitute 6.4% of the inner bark, increasing from 5.7% at the cambium to 8% in the outer bark as a result of dilation.
Ultrastructural aspects of conidiogenesis in Gonatobotryum apiculatum
Authors: Cole Garry T.
Published: September 2008

Conidium formation in Gonatobotryum apiculatum (Peck) Hughes is identified as holoblastic (Kendrick 1971. Taxonomy of Fungi Imperfecti. University of Toronto Press). Morphological features of this developmental process are demonstrated using scanning and transmission electron-microscopic and freeze-etch techniques. The wall relationships between scars (denticles) on the surface of conidiogenous cells and basal abstriction scars of conidia are demonstrated. The presence of cytoplasmic deposits of insoluble polysaccharides and crystalloids in the apex of conidiogenous cells are noted and possible functions of these inclusions are discussed. "Paramural bodies" (Marchant and Robards 1968. Ann. Bot. 32: 457) in conidiogenous cells are also described. A diagrammatic interpretation of conidiogenesis in this species is presented.
Ultrastructural changes caused by lipid extraction of pollen of Pinus echinata
Authors: Hess W. M. , Weber D. J. , Allen J. V. , Laseter J. L.
Published: September 2008

Lipid-extracted and non-lipid-extracted Pinus echinata Mill. pollen grains were examined by light microscopy, scanning electron microscopy, and freeze-etching and thin-sectioning procedures used with transmission electron microscopy. Non-lipid-extracted pollen grains floated in aqueous solutions, sacci were not collapsed, and organelles were not disrupted. Lipid-extracted pollen grains did not float in aqueous solutions, sacci collapsed, and organelles were disrupted. In the vacuum of the scanning electron microscope the sporoderm in the aperture-bearing area collapsed causing sacci to come into contact with each other.
Sugar concentration gradients of the sugar beet plant in relation to translocation
Authors: Suzuki Michio , Mortimer D. C.
Published: September 2008

An increasing sugar gradient in the rib, a decreasing gradient in the upper region of the petiole, and a sharp increase in the base of the petiole were found when transverse segments of the rib and petiole of a sugar beet leaf or the isolated vascular bundles as a whole were analyzed. The sugar concentration and the gradient pattern varied considerably with the leaf position in the ontogenic sequence. The proportion of assimilated 14C exported as sucrose was highest for leaves of intermediate age, which were at the nearly mature stage. Mature and old leaves exported less 14C and young leaves, which had a high sugar concentration in the blade and a sharply decreasing gradient in the petiole, exported very little. Analysis of vascular bundles in the petiole which serve the tip and basal regions of the blade after 14CO2 incorporation into the blade indicated that a much larger amount of 14C-sucrose entered into and moved through the basal bundle than into and through the tip bundle.
Afterripening and germination of seeds of American highbush cranberry (Viburnum trilobum)
Authors: Fedec Paul , Knowles R. H.
Published: September 2008

Seed of the American highbush cranberry, Viburnum trilobum Marsh., kept at germinative conditions of 20 °C, required 328 days to reach 92% germination. Initially, about one-half the seed germinated within 120 days. After a 120-day lag, the balance germinated. Afterripening, with as little as one cycle of alternating temperature (1 week at 20 °C and 1 week at 2 °C) shortened the time to total germination by [Formula: see text] months. The inductive effect of afterripening was studied in relation to utilization of the high lipid reserve present in the endosperm. No appreciable changes in polar and non-polar lipids occurred during prolonged exposure to either afterripening or germinative conditions, indicating that afterripening is not associated with lipid degradation. Gibberellic acid (GA3) had little effect on seed germination but successfully overcame epicotyl dormancy of the seedling.
An examination of the floristic zone concept with special reference to the northern limit of the Carolinian zone in southern Ontario
Authors: Thaler G. R. , Plowright R. C.
Published: September 2008

Several features of the concept of floristic zonation, as a special case of biogeographical zonation in general, are examined. A distinction between description and hypothesis testing provides a preliminary systematization of methods used to detect the presence of zonation by analysis of distribution records. It is argued that the use of range limits largely fails to take the statistical nature of distribution records into account. Accordingly, three ordinational methods which do not depend upon range limits are applied to presence–absence data for 100 species of vascular plants occurring in southern Ontario. Two of these methods, canonical correlation and principal-components analysis, explore the idea that linear combinations of differential weightings upon the members of a set of taxa may demonstrate clearer geographical trends than merely treating all taxa as equally important trend-setters. The results of the study appear to bear this out. No sharply demarcated zonal boundaries emerged from the analyses, but two of the methods indicated the presence of weakly developed tension zones which may be taken as evidence of floristic zonation in southern Ontario.
Encystment and germination of the parasitic chytrid Rozella allomycis on host hyphae
Authors: Held Abraham A.
Published: September 2008

Zoospores of the obligately parasitic chytrid Rozella allomycis which settle upon hyphae of the water mold host, Allomyces arbuscula, encyst and germinate before their protoplasts penetrate into the host cytoplasm. This process has been examined by light and electron microscopy. Three stages which follow the attachment to the host and the retraction of the zoospore's flagellum are described: (1) the early cyst lacks a wall; it is discoid, and its shape is maintained by the coil of the retracted axoneme which forms its rim; (2) a cyst wall is formed while multivesicular bodies occur at the cell periphery and eventually disappear; a germ tube starts to grow at the point of attachment; and (3) the firm-walled cyst is spheroidal; it has a fully developed germ tube with a specialized class of vesicles; it also forms a distal, flattened vacuole whose swelling eventually injects the Rozella protoplast into the host; at this stage the retracted axoneme has disappeared and the cell's organelles have undergone extensive changes. Electron-dense, "gamma-like" granules enclosed in vacuoles may play a major role in the formation of both the cyst wall and the distal vacuole. These granules appear to give rise to small vesicles, and thus to multivesicular bodies; the distal vacuole appears to form by coalescense of gamma-like vacuoles.The general sequence of encystment and germination resembles that found in other Chytridiomycetes, both saprophytic and parasitic. However, the distal vacuole and the vesicles in the germ tube appear to be parasitic adaptations and are shared by obligate intracellular parasites from several unrelated groups of zoosporic fungi.
Lipid composition of morning glory (Ipomoea sp.) cells grown in suspension cultures
Authors: Song Moonja , Tattrie Neil
Published: September 2008

Total fatty acids of morning glory (Ipomoea sp.) cells grown in suspension cultures for 8 days were determined. Triglycerides, diglycerides, mono- and di-galactosyl-diglycerides were isolated and their constituent fatty acids were analyzed. Sterols and sterol esters as well as the major phospholipids were quantitatively isolated and analyzed at various stages of growth. Palmitic and linolenic acids were the predominant fatty acids in all the isolated compounds until the 5th day of growth when the linolenic acid rapidly decreased and the oleic acid increased until the end of the growth period. Stearic acid remained at about 5% during the entire growth period. Linoleic acid increased from 12 to 20% between 6 and 30 h, then decreased to the original value of the inoculum. The free sterols, β-sitosterol, stigmasterol, and campesterol (72:18:10) changed very little during the 8-day growth period. The three main phospholipids (phosphatidyl-choline, phosphatidyl-ethanolamine, and phosphatidyl-glycerol) increased rapidly between 12 and 48 h of growth but changed very little during the next 6 days.
Formation of fruits on rootless plants
Authors: Peterson Carol A. , Fletcher R. A.
Published: September 2008

Fruits develop on tobacco, tomato, pea, and bean plants even though the roots are removed at the time of flowering and the formation of adventitious root primordia is prevented by periodic excision of the bases of the stems. Pea and bean fruit growth in the absence of roots is limited by the accelerated senescence of the foliage. Experiments with tomato shoots had to be concluded when the fruits were still enlarging since all the subtending stem had been removed. Tobacco fruits will reach maturity on stems without roots and will produce viable seed. Removal of roots from young bean plants results in a rapid and drastic inhibition of stem growth. In contrast, when roots are removed during flowering, pod growth is not severely inhibited until much later when the foliage has senesced. Seeds developing in the absence of roots contain well-differentiated embryo axes and cotyledons. They are smaller in size than those of the controls, an effect which can probably be explained by the reduced food supply available to them from the senescing foliage. The appreciable degree of fruit and seed development after root removal indicates that the developing fruits and seeds probably do not depend exclusively on roots for their supply of growth regulators.
Hypersensitive resistance. Isolation and characterization of glycoproteins from plants with localized infections
Authors: Brown Robert G. , Kimmins Warwick C.
Published: September 2008

Local lesions were induced on Phaseolus vulgaris var. Pinto by inoculation with tobacco necrosis virus. At 24–36 and 120 h, alkali-soluble protein–polysaccharide complexes (I and II, respectively) were isolated from the primary leaves.Amino acid analyses indicated that the protein components of I and II were similar and related in composition to known plant cell wall proteins. The two preparations differed principally in their carbohydrate moieties; preparation II contained more glucose and this glucose was shown to occur as a β-(1 → 4)-linked glucan. Preparation I contained mostly (1 → 4)-linked glucose but, in addition, (1 → 3)-linked glucose (callose-type linkage) was present. Both complexes contained acid-labile arabinose as well as mannose and galactose.
Hypersensitive resistance. The role of cell wall glycoproteins in virus localization
Authors: Kimmins Warwick C. , Brown Robert G.
Published: September 2008

Glycoprotein complexes were extracted from Phaseolus vulgaris var. Pinto infected with tobacco mosaic virus (TMV) or with tobacco necrosis, or after sham inoculation. After all three treatments there were two distinct periods when glycoproteins were at a maximum. The product accumulated during the primary response contained both β(1 → 3)- and β(1 → 4)-linked glucopyranosyl residues. That of the secondary response contained mainly β(1 → 4)- but no β(1 → 3)-linked residues. These two glycoprotein complexes were absent from healthy non-inoculated plants.The similarity between results from sham-inoculated plants and those inoculated with virus suggests that the glycoprotein formation is a wound response, induced through mechanical inoculations and not through virus infection. Deposition of glycoproteins within the cell walls in advance of infection may localize the virus by reducing the number of intercellular pathways for virus spread. If virus has already spread beyond the zone of cell wall modifications, localization will be incomplete.
Photosynthetic O2 evolution and apparent H+ uptake by slices of greening barley and maize leaves in aerobic and anaerobic solutions
Authors: Lüttge Ulrich
Published: September 2008

Apparent rates of photosynthetic O2 evolution and light-dependent pH change (Δ[H+]) were measured in solutions containing leaf slices and bubbled with gas streams of varied composition. Intracellular recycling of O2 and CO2 between photosynthetic and respiratory reaction systems seems to be possible in green cells in the light. As a result of photosynthetic O2 evolution, the tissue and the solution are never strictly anaerobic even after prolonged bubbling with N2. Internal gas exchange is more pronounced in slices from the leaves of maize (a C-4 plant) having the complex Kranz tissue differentiation of mesophyll and bundle sheath, than in the leaves of barley (a C-3 plant).Light-dependent Δ[H+] is observed under all conditions used, i.e. in air, air – CO2, pure N2, and N2 + CO2. During the early stages of greening of etiolated leaves, Δ[H+] is found to be closely related to photosynthetic O2 evolution. After prolonged greening, Δ[H+] is larger in air – CO2 than in air. In pure N2, Δ[H+] is smaller and apparent O2 evolution is larger than in N2 + CO2. These results are discussed in relation to the hypothesis that part of light-dependent Δ[H+] is independent of concomitant photosynthetic CO2 fixation.
Studies of hypodermataceous needle diseases. III. The association of Sarcotrochila macrospora n. sp. and Hemiphacidium longisporum n. sp. with pine needle cast caused by Davisomycella ampla and Lophodermella concolor
Authors: Ziller W. G. , Funk A.
Published: September 2008

Two new species of Hemiphacidiaceae on needles of lodgepole pine (Pinus contorta Dougl.) are described and illustrated. Their taxonomic positions, characteristics in culture, and apparent roles as natural control agents of pine needle cast are discussed.
Floral development of Myrica gale and the controversy over floral concepts
Authors: Macdonald Alastair D. , Sattler Rolf
Published: September 2008

Two bracteoles form by divisions in the second layer of cells on the transversal flanks of the floral apex. Four stamens form in the male by cell divisions in the third layer of cells; one develops opposite each bracteole and two form in the median plane on either side of the floral apex. In the female bud a girdling gynoecial primordium forms by periclinal divisions in the second layer. Growth becomes localized in two or three zones in the gynoecial primordium; upward growth results in the formation of two or three stigmas. The gynoecial wall forms by intercalary growth above and below the region of bracteole attachment. The ovule develops by the resumption of growth of the floral apex. A single vascularized integument, formed at first by periclinal divisions in the protoderm, encloses the nucellus. The development and pattern of the vascular tissue is described. Four conceptual frameworks regarding the morphological nature of the flower are outlined and the data derived from this study are analyzed in relation to each framework. The interpretations are conflicting and it is considered that this is due, in part, to an a priori establishment of mutually exclusive categories.
The nature of the "nuclear cap" and nuclear behavior in Phytophthora infestans
Authors: Sivak Bela
Published: September 2008

The nature of the "nuclear cap" of sporangial nuclei of Phytophthora infestans was studied after treatment with 1.0 N HCl, separate digestions with RNase and DNase, and staining with Feulgen and orcein stains. The results strongly support the conclusion that DNA is a major constituent of the "nuclear cap." Although they provide some supporting evidence for the conclusion that sporangia become multinucleate through migration of nuclei into them, the results also indicate that nuclear division may take place within young sporangia.
Germination of Psilotum spores in axenic culture
Authors: Whittier Dean P.
Published: September 2008

Spores of Psilotum nudum (L.) Griseb. germinated in axenic culture on a nutrient medium containing mineral elements and 0.25% sucrose after 6 months in the dark.
Ultrastructure of the conidia of Helminthosporium maydis
Authors: White J. A. , Calvert O. H. , Brown M. F.
Published: September 2008

Mature conidia of race O and of race T of Helminthosporium maydis were examined microscopically to characterize the general ultrastructure of the conidia and to determine if the two races could be differentiated on the basis of conidial morphology. At the light-microscope level, the two races could not be separated. Histochemical analyses showed that, in both races, the cell wall was composed of chitin with melanin pigmentation. Electron-microscopic examination of thin-sectioned conidia revealed the presence of two distinct cell walls. Cross-walls were found to have typical ascomycetous septal pores. The types of cell organelles found in mature conidia did not provide any indication of the pathogenic capability of the fungus. No consistent differences were found in the ultrastructure of the two races and it was concluded that race T could not be differentiated from race O on the basis of conidial morphology.
The psilopezioid fungi. IV. The genus Pachyella (Pezizales)
Authors: Pfister Donald H.
Published: September 2008

Pachyella, characterized by amyloid asci, globose cells in the ectal excipulum, hyphoid hairs, and gelatinous tissue, is treated monographically. A total of six species are discussed. The new combinations P. adnata, P. violaceonigra, and P. megalosperma are proposed and one new species, P. punctispora, is described.
Isoperoxidases of (IAA oxidase) oxidase in oat coleoptiles
Authors: Gordon William R. , Henderson James H. M.
Published: September 2008

Eight constitutive isoperoxidases were separated by the disc method of polyacrylamide gel electrophoresis from a lyophilized extract of 8-day-old oat (Avena sativa L., cv. Victory) coleoptiles. Both anodic and cathodic isoperoxidases were studied and differences in electrophoretic mobilities and hydrogen donor substrate specificities were revealed. In addition, by enzyme assay, cathodic and anodic isoenzymes were shown to possess differences in peroxidase and IAA (indole-3-acetic acid) oxidase activities.Treatment of coleoptiles with 0.07 mM IAA for 24 h resulted in the repression of two slow-migrating anodic isoperoxidases; however, the same treatment also resulted in the induction of two slow-migrating cathodic isoenzymes which were shown to exhibit peroxidase and IAA oxidase activities.
A clarification of the chromosome number situation in Sanguisorba canadensis
Authors: Mulligan Gerald A. , Cody William J.
Published: September 2008

Although eastern North American populations of Sanguisorba canadensis L. are reported to be octoploid and plants of western North America reported to be tetraploid, it was found that this species is usually tetraploid, 2n = 28, throughout its range. No octoploids were found among the plants studied, even in material from the locations where octoploids have been reported to occur.
A palynological study of postglacial vegetation changes in the University Research Forest, southwestern British Columbia
Authors: Mathewes Rolf W.
Published: September 2008

The postglacial vegetation history of the University of British Columbia Research Forest was investigated using percentage and absolute pollen analysis, macrofossil analysis, and radiocarbon dating. A marine silty clay deposit records the oldest (12 690 ± 190 years before present (B.P.)) assemblage of terrestrial plant remains so far recovered from the postglacial of south-coastal British Columbia. Lodge-pole pine (Pinus contorta) dominated this early vegetation, although some Abies, Picea, Alnus, and herbs were also present. Sediment cores from two lakes were also studied. The older is Marion Lake, where five pollen assemblage zones are recognized, beginning with a previously undescribed assemblage of Pinus contorta, Salix, and Shepherdia in clay older than 12 350 ± 190 B.P. The pollen diagram from Surprise Lake (11 230 ± 230 B.P.) is divided into three pollen zones which show the same major trends of vegetation change as the Marion Lake diagram.The first report of the postglacial vegetation history of cedar (Thuja and perhaps Chamaecyparis) in southwestern British Columbia is presented from pollen and macrofossil analyses.At about 10 500 B.P. in both lakes, pollen of Douglas fir (Pseudotsuga menziesii) began a rapid increase, probably in response to climatic amelioration. The palynological evidence, supported by well-preserved bryophyte subfossils, suggests that humid coastal conditions have prevailed in the study area since about 10 500 B.P., with virtually no evidence for a classical Hypsithermal interval between 8500 B.P. and 3000 B.P.
Callus formation from mesophyll protoplasts of Pisum sativum
Authors: Constabel F. , Kirkpatrick J. W. , Gamborg O. L.
Published: September 2008

Protoplasts isolated from mesophyll of Pisum sativum L. cv. Century, and cultured in 0.2-ml droplets of B5 medium with 1.0 mg/liter (2,4-dichlorophenoxy)acetic acid (2,4-D) or 1-naphthaleneacetic acid (NAA) and 2.0 mg/liter kinetin regenerated cell walls within 2–3 days. The resulting cells began to divide and form calli after 19 days of culture. Protoplast survival depended on keeping the leaf material in the dark for at least 30 h before use.
Taximetrics of Loudetia (Gramineae) based on leaf anatomy
Authors: Lubke R. A. , Phipps J. B.
Published: September 2008

This paper reports the results of a taximetric study of the genus Loudetia Hochst. ex Steud. (Arundinelleae, Gramineae) based on leaf anatomical data. Two interrelated questions were posed: firstly, whether leaf anatomical data would be found to generate taxonomic results conformable to those from morphological data; and secondly, what light might be thrown on the affinities of certain taxa of more obscure or controversial relationships, viz. Loudetia jaegeriana, L. togoensis, Loudetia sect. Pleioneura, and Rattraya. It was discovered that a generalized affinity to the preexisting morphological taxonomies existed, and that L. jaegeriana, L. togoensis, and Loudetia sect. Pleioneura (with Rattraya) tended to be not only distant from each other but not closely related to the main section of Loudetia.
Natural plant recolonization of surficial disturbances, Tuktoyaktuk Peninsula Region, Northwest Territories
Authors: Hernandez Helios
Published: September 2008

Seismic lines or winter roads were sampled where they passed through three different plant communities in the Mackenzie Delta and through four of the major tundra communities in the Tuktoyaktuk Peninsula. Winter seismic lines have been less detrimental than summer lines for all communities examined. Although winter roads through upland areas remove most of the vegetation cover, the peat layer usually remains intact and soil energy budgets are relatively little affected. Wetland sedge meadows are highly susceptible to summer disturbance but least affected by winter operations. Winter-disturbed forested and tall shrub communities recover faster initially than similarly disturbed upland tundra communities.Eriophorum vaginatum and Carex bigelowii appeared to be stimulated by disturbances which did not eliminate them, with Eriophorum often flowering more abundantly in disturbed areas. This probably results from warmer soils and greater nutrient uptake.Summer seismic lines (1965), originally bladed to permafrost, resulted in exposure of mineral soil and thus led to secondary succession in tundra communities. Arctagrostis latifolia, Calamagrostis canadensis, Poa arctica, and Luzula confusa are the most typical and abundant pioneers of upland mesic sites. Wet sites are colonized predominantly by Arctophila fulva and Carex aquatilis. Once established, these species expanded rhizomatously. Six years after exposure of mineral soil, plant cover was usually 30 to 50%.Thaw was generally increased 80 to 100% where mineral soil was exposed, 30 to 50% if the peat remained intact, and 10% if plant cover was little altered. Subsurface ice has occasionally been exposed, resulting in thermokarst subsidence. Water erosion has not been a factor, probably because of the low precipitation in the region.
Structure of the lichen Parmelia aurulenta
Authors: Fahselt D. , Hayden D. B. , Mirando M.
Published: September 2008

The foliose lichen Parmelia aurulenta Tuck. (Parmeliaceae) was examined using scanning electron microscopy and transmittance electron microscopy. The algal component was identified as Trebouxia and the physical relationship between algal cells and fungal hyphae was studied. An impression of the three-dimensional relationship between the two symbionts was obtained with the scanning electron microscope, and the sites of extensive crystal deposition were identified.
Electrophoretic analysis of isozymes from seeds of Pinus, Abies, and Pseudotsuga
Authors: Juo Pei-Show , Stotzky G.
Published: September 2008

Isozyme patterns of L-leucine-amino-peptidase (LAP), esterase, and peroxidase in extracts from conifer seeds (eight species of Pinus, Abies concolor Hoopes, and Pseudotsuga taxifolia Britt.) indicated that certain specific isozyme patterns might be useful in systematic studies of conifers. The isozyme patterns of LAP from these seeds showed an apparent phylogenetic relationship. Eight different LAP bands were detected, and all eight species of Pinus displayed the same three LAP bands. The two slowest moving LAP bands were found to be common to all 10 species, whereas the mobility of the other LAP bands varied among species. Isozyme patterns of esterase from seeds of Pinus, Abies, and Pseudotsuga varied from species to species, and no species displayed the same number of bands. The number of esterase bands detected varied from 5 to 16, and no phylogenetic relationships were apparent. The banding patterns of peroxidase from these conifer seeds, which ranged from three to nine bands, also appeared to be species specific, and no common trends or homologies were apparent.
Ethylene production as related to dwarfness and earliness in plants
Authors: Aharoni Y. , Phan C. T. , Spencer Mary
Published: September 2008

Maximum production of ethylene by whole bean and wheat plants occurred early in the life of the plants. For both bean and wheat, dwarf cultivars matured earlier and produced more ethylene than plants of normal size. The differences in ethylene production were particularly evident in the young plants.
The identification of Mycelium radicis atrovirens (Phialocephala dimorphospora)
Authors: Richard C. , Fortin J.-A.
Published: September 2008

Mycelium radicis atrovirens is known as a sterile fungus colonizing the surface of rootlets of trees in the boreal forest. Microscopic examination of 41 isolates conforming in vegetative morphology to the type description of this fungus revealed the presence of phialoconidia corresponding to Phialocephala dimorphospora in 15.
A new structure containing cyst-like bodies in apothecia-bearing sclerotia of Sclerotinia borealis
Authors: Tu J. C. , Colotelo N.
Published: September 2008

A structure containing numerous cyst-like bodies bounded partially or completely by a double membrane was found in thin sections of sclerotia of Sclerotinia borealis Bub. and Vleug. This structure was only observed in sclerotia bearing apothecia.
Prevalence of Dendryphion nanum in field soils in Saskatchewan with special reference to rape in the crop rotation
Authors: Chinn S. H. F.
Published: September 2008

The prevalence of conidia of Dendryphion nanum was determined by the flotation count method in soil samples obtained from four groups of fields. The first three groups consisted of 25 rape, 25 cereal, and 23 fallow fields. History of prior crops grown was unknown. The fourth group consisted of 10 wheat fields that had never been cropped to rape. Conidial populations ranged from 22 to 3473 conidia per gram soil for rape, 0 to 1680 for cereal, 0 to 547 for fallow, and 0 to 34 for wheat fields. The mean numbers for these groups of fields were 948, 354, 86, and 6 respectively.Prevalence of D. nanum conidia apparently was promoted by cropping to rape and, to a lesser extent, the presence of wild mustard in fields. The populations of conidia were much higher in the first three groups of fields in an intensive rape-growing area around Melfort, Saskatchewan, than in fields in less intensive areas. Evidence is presented to support the reliability of the flotation count method. This method and that used for the isolation of D. nanum directly from soil are described.
A biosystematic analysis of the Caltha leptosepala (Ranunculaceae) complex in the Rocky Mountains.: III. Variability in seed and gross morphological characteristics
Authors: Morris Michael I.
Published: September 2008

Part three of a biosystematic study of the Caltha leptosepala complex in the Rocky Mountains involves analyses of embryology and gross morphology. Data obtained from both the natural populations investigated and from dried herbarium material support the premise that only one species, Caltha leptosepala, can be taxonomically justified for the Rocky Mountains.
Early seed development in hexaploid triticale
Authors: Kaltsikes P. J.
Published: September 2008

The development of the embryo, endosperm, and antipodals was studied in five hexaploid triticale lines. The egg cell was fertilized 10–15 h after pollination. The first division of the zygote occurred 15–20 h later. Ninety-six hours after pollination there was a twofold difference among the lines in the number of embryo cells, which ranged from 17 to 31. The polar nuclei were fertilized 4–5 h after pollination and the first division of the primary endosperm nucleus took place 2–3 h later. At 60 h the lines examined fell into two groups with respect to endosperm development: one group included 6A190 and 6A250, both raw amphiploids, which had 1032 and 486 endosperm nuclei, respectively; and another which included Rosner, Armadillo 458, and 6517, all products of artificial selection, with 209, 201, and 98 endosperm nuclei, respectively. The first five or six endosperm divisions were highly synchronized while later a gradient was established. Cellularization of endosperm was first observed 96 h after pollination. No appreciable amount of mitotic abnormalities was observed in the endosperm nuclei. In all lines examined endosperm nuclei were found with DNA amount exceeding 6C.The number of antipodals, some of which were highly endopolyploid (up to 256C), ranged from 10 to 30 within and among lines. Disintegration of the antipodals began about 3 days after pollination in 6A190, at 4 days in Rosner, and at 5 days in the other lines. The rate of endosperm development and especially the disintegration of the antipodal complement seemed to be positively related with the amount of seed shrivelling observed in the lines studied.
Ultrastructure of hyphal walls and septa of Cronartium ribicola on tissue cultures of Pinus monticola
Authors: Robb Jane , Harvey A. E. , Shaw Michael
Published: September 2008

Colonies of the rust fungus Cronartium ribicola J. C. Fischer were grown axenically and then transferred so that they lay immediately next to callus cultures of the pine host (Pinus monticola Dougl.). Twelve days after the establishment of this association samples of the fungal mycelium taken 2 mm away from the pine callus and at the host–parasite interface were fixed for electron microscopy. Differences were found in the appearance and thickness of the lateral walls and extracellular coatings depending on the proximity of the fungus to the host–parasite interface. Septa were intermediate in structure between the Ascomycete and dolipore types. The origin of the extracellular sheath is discussed.
Biochemical and physiological studies on dormancy release in tree buds. I. Changes in degree of dormancy, respiratory capacity, and major cell constituents in overwintering vegetative buds of Populus balsamifera
Authors: Bachelard E. P. , Wightman F.
Published: September 2008

Changes in the degree of dormancy, rate of growth, respiratory capacity, and in the amounts of several major cell constituents (sugars, protein, amino acids, cell wall materials, starch, and chlorophyll) were examined in vegetative buds of Populus balsamifera L. as they developed from midwinter dormancy to the spring flush of growth in 1972. A significant decrease in the dormancy status of buds occurred during the period March 17 to April 3, and this was accompanied by an increased level of catabolic metabolism of carbohydrates and protein. A further change to anabolic metabolism at the end of April, nearly 2 weeks before bud burst, resulted in a net synthesis of cellular constituents in preparation for bud burst.
A classification of terrestrial vegetation near McMurdo Sound, continental Antarctica
Authors: Longton R. E.
Published: September 2008

Eleven plant sociations are reported from the McMurdo Sound region of continental Antarctica, and they are grouped in the Alga, Fruticose and Foliose Lichen; Crustaceous Lichen; and Short Moss Turf and Cushion subformations of the Antarctic Non-vascular Cryptogam Tundra formation. Their inclusion necessitated only minor modification of a vegetation classification developed in the maritime Antarctic.The most widespread vegetation consisted of sparsely developed communities of turf- and cushion-forming mosses in habitats ranging from dry cinder slopes to sand and gravel in seepage areas and by meltwater streams. The bryophyte colonies seldom exceeded 4 cm in depth, and although total plant cover within the communities locally reached 85%, it was more frequently under 5%. The Sarconeunim association appeared to tolerate more arid conditions than the Bryum association, whose communities occasionally merged with algal sociations occupying certain of the streams. Exposed rock habitats normally supported at most small scattered thalli of crustaceous lichens, well-developed lichen communities being rare.
Revisions of the microcyclic Puccinia species on Saxifragaceae
Authors: Savile D. B. O.
Published: September 2008

Abundant added material and use of phase-contrast microscopy show that Puccinia heucherae, P. austroberingiana, and P. saxifragae are separate species and that each is divisible into two or more populations. Described as new are P. harae on Chrysosplenium, axillare; P. saxifragae-gei on Saxifraga geum; P. heucherea vars. meridionalis, minor, cordillerana, diffusistriata, and japonica new vars., and var. saxifragae-micranthae (Barclay) new comb.; P. austroberingiana ssp. saxifragarum; P. saxifragae var. curtipes (Howe) Diet., vars. longior, heucherarum, holochloae and mitellae new vars.; P. pazschkei var. ferrugineae new var. New host records, correction of erroneous host records, and new biogeographic data throw additional light on the radiation of Saxifraga and emphasize a few erroneous assignments of species to sections or subsections.
Aspects of the life history and ecology of Porphyra linearis (Bangiales, Rhodophyceae) in nature
Authors: Bird C. J.
Published: September 2008

The life history of P. linearis Grev. in nature was studied for 2 years at Sandy Cove, Halifax County, Nova Scotia, Conchospores of this winter alga were present in the supralittoral zone as early as August, although thalli were not visually apparent until mid-October to late October. The first major deposition of conchospores coincided approximately with decreasing sea temperature at 13–14 °C. Spores were deposited throughout the winter until March, when sporulation presumably declined and few new thalli appeared on the study site. A few conchospores were retrieved from the supralittoral zone in April, when extant thalli were bleached or moribund, and as late as June, after the population had died. Conchocelis of P. linearis was not found in the supralittoral habitat of the leafy phase, but several specimens were located at a depth of 9 m in the sublittoral zone near the study site. Leafy thalli became fertile 3–5 weeks after their appearance on the site, and were largely dioecious; broader thalli in the upper littoral zone were frequently monoecious, and displayed α- and β-spores simultaneously. Development of the population was enhanced by thin films of moisture but not by standing water such as tide pools; nor did young P. linearis thrive in Ulothrix flacca – Urospora penicilliformis associations. Death of leafy thalli in spring appeared to result from an interaction of increasing temperature and photoperiod. Alternation of the leafy phase with conchoecelis is obligatory in P. linearis; vegetative reproduction by neutral spores was not observed, and thalli did not perennate via the remnants of basal portions which sometimes persisted through the summer. Intergradation of P. linearis with P. umbilicalis is discussed.
Biosystematics of Coriolus hirsutus and C. pubescens. I. Interfertility studies
Authors: Edwards Roger , Kennedy Lorene L.
Published: September 2008

Interfertility tests between Alberta collections identified as Coriolus hirsutus, C. pubescens, C. velutinus, C. zonatus, and C. versicolor have shown that there are only two distinct species of this complex in Alberta, each with a range of morphological variation. Both these species, which are being called Coriolus hirsutus and C. pubescens, have the tetrapolar type of fertility. Isolates of basidiocarps from Sweden identified as Coriolus hirsutus were intersterile with Alberta isolates of this species, which suggests the existence of two different species. Cultures of C. versicolor (Ontario) were unilaterally dikaryotized by C. hirsutus and to a lesser extent by C. pubescens, indicating very close relationship. Dark pigment lines frequently formed between paired isolates of both distantly related and closely related cultures, indicating that it is not mating-type factors which control pigment formation in the contact zone.
Pollen morphology of Rhynchosia and Eriosema (Fabaceae)
Authors: Ramcharan E. K. , McAndrews J. H. , Grear J. W.
Published: September 2008

The closely related genera Rhynchosia and Eriosema have tricolporate pollen. Twenty-two species of Rhynchosia and nine species of Eriosema were examined with the light microscope. Most of the species have isopolar-type grains, but 11 species have the hitherto rarely described heteropolar-type pollen, i.e. on a single grain, the ends of the colpi subtend a greater area at one pole than at the opposite pole. Duplicate examination of 13 species indicates that polarity types are constant within those species. While the genera cannot be separated on the basis of pollen morphology alone, there are some pollen characters which embrace most species in any one genus. Eriosema species are mostly heteropolar (67%) and Rhynchosia are predominantly isopolar (77%). The lumina of the reticulum of Rhynchosia tend to be smaller than those of Eriosema and, with one exception, the muri of Eriosema have acute tops while those of Rhynchosia are obtuse. Scanning electron micrographs illustrate pollen morphology.
A correlation between rodlet orientation and conidiogenesis in Hyphomycetes
Authors: Cole Garry T.
Published: September 2008

Freeze-etching has revealed changes in the orientation of rodlet fascicles on the surface of the outer wall layer of conidia and conidiogenous cells at successive stages of development. Specific patterns of rodlet fascicles reflect the progressive increase in cell volume and change in shape characteristic of 'blastic' conidium development in Gonatobotryum apiculatum. Rodlet patterns over most of the wall surface of conidia of Oidiodendron truncatum and Geotrichum candidum, on the other hand, are not significantly different from the patterns of rodlet fascicles on the wall of the determinate, fertile hyphae from which the conidia arose. This latter structural–developmental relationship is suggested to be characteristic of the 'arthric' mode of conidiogenesis. It is demonstrated, however, that conidium formation in Oidiodendron truncatum does involve some meristematic activity in addition to conversion and disarticulation of pre-existing hyphal elements. A diagrammatic interpretation of these changes in rodlet patterns during conidiogenesis is presented.
Occurrence and levels of the phytoalexin phaseollin in relation to delimitation at sites of infection of Phaseolus vulgaris by Colletotrichum lindemuthianum
Authors: Rahe J. E.
Published: September 2008

Sequential quantitative analyses of phaseollin associated with individual sites of infection by Colletotrichum lindemuthianum on etiolated hypocotyls of Phaseolus vulgaris provide further insight concerning the possible function of phaseollin in compatible and incompatible host response. When detected, phaseollin was localized in and (or) around individual infection sites; it was not detected in adjacent healthy tissue. Its occurrence was correlated with the time of appearance of visible, necrotic flecks at sites of incompatible response. It was not detected at visibly necrotic sites of compatible response until these became delimited in appearance, after which it occurred in large amounts. Delimitation at these sites occurred well after visible necrosis was first apparent. At high levels of infection, individual sites of compatible infection coalesced before delimitation, and in such instances phaseollin was virtually absent for the duration of the experiments. The levels of phaseollin occurring at individual infection sites indicate that it does not function as the primary determinant of interaction type, but is associated with delimitation at sites of both compatible and incompatible interaction. With respect to phaseollin production, the difference between these interactions was clearly one of time of occurrence, rather than amount produced.
Biosystematics of the genus Populus L. I. Distribution and morphology of native Manitoba species and variants
Authors: Ronald W. G. , Lenz L. M. , Cumming W. A.
Published: September 2008

Twenty-four morphological characters of native Manitoba Populus were studied in an attempt to delineate species and variants and provide keys for correct identification. The results support the hypothesis that the variants have originated from intersectional hybridization of P. balsamifera L. (section Tacamahaca Spach.) and P. deltoides Marsh. var. occidentalis Rydb. (section Aegeiros Duby). Populus × jackii Sarg. encompasses the collective group of individuals resulting from this hybrid cross. The hybrid individuals are widely distributed and occur commonly where the two parental species are growing together.
Biosystematics of the genus Populus L. II. Chemotaxonomy, phenology, fertility, and segregates of native Manitoba species and variants
Authors: Ronald W. G. , Lenz L. M. , Cumming W. A.
Published: September 2008

Chemotaxonomical, phenological, fertility, and hybrid segregation characteristics have further elucidated the relationships of Populus species and variants in southern Manitoba.Species chromatograms, made with bark collections from widely separated localities, were consistently uniform and proved reliable for species identification. Chromatograms of variant individuals were unlike those of any species examined. Flowering and seed shedding in P. balsamifera L., P. deltoides Marsh. var. occidentalis Rydb., and variants occurred together and about 2 weeks and 4 weeks later than respective dates for P. tremuloides Michx.Hybrid fertility, measured by seed set was lower than the expected values for fully fertile hybrids of P. balsamifera and P. deltoides var. occidentalis. All variant populations, except from Grand Beach, produced greater than 90% vigorous seedlings. Seedling progenies from several apparent F1 hybrids segregated towards P. balsamifera and P. deltoides var. occidentalis. No segregates similar to or approaching P. tremuloides were recovered.