bluuebunny/crossref_metadata_2025 huggingface dataset:
Phylogenetic relationships in subtribe Poinae (Poaceae, Poeae) based on nuclear ITS and plastidtrnT–trnL–trnF sequencesThis paper is one of a selection of papers published in the Special Issue on Systematics Research.
Authors: Gillespie Lynn J. , Soreng Robert J. , Bull Roger D. , Jacobs Surrey W.L. , Refulio-Rodriguez Nancy F.
Published: September 2008

The worldwide temperate subtribe Poinae comprises the largest grass genus, Poa (500+ species), and multiple additional small genera. We explore generic boundaries and relationships among genera of Poinae using nuclear ribosomal internal transcribed spacer data (ITS) and plastid trnT–trnL–trnF (TLF) sequence data. ITS and TLF analyses are mostly congruent with regards to circumscription of genera, and with respect to relationships among Poinae genera, but tree structure is generally better supported among genera in the ITS strict consensus tree. ITS and TLF both support two main Poinae lineages: (i) Poa and (ii) a clade comprising all other sampled Poinae. Nine small genera were nested within the large Poa clade, including Aphanelytrum , Dissanthelium , and Tovarochloa , supporting inclusion of these as sections within Poa. In the second clade, three subclades support close relationships among Nicoraepoa , Hookerochloa , and Arctagrostis ; Arctophila and Dupontia ; and Apera , Bellardiochloa , and Ventenata . Genera of the related subtribes Alopecurinae, Cinninae, and Miliinae were mixed among or in part external to Poinae in different ways in ITS and TLF analyses, and only subtribe Puccinelliinae was strongly supported and monophyletic. ITS analyses supported placement of Catabrosella , Hyalopoa , and Paracolpodium in Puccinelliinae (no TLF data available). The position of Poa subgenus Arctopoa is incongruent between the two analyses: TLF data support inclusion within Poa and ITS data place it outside of Poa. Similarly, TLF data resolves the genus Aniselytron outside of Poa, whereas ITS data place it within Poa. Based on these results and a consideration of morphology, we recognize Arctopoa and Aniselytron as genera, probably of ancient hybrid origins. Nothogenus  × Duarctopoa is coined for Arctopoa × Dupontia, with a single nothospecies  × Duarctopoa labradorica . A new combination is provided for Poa subg. Sylvestres .
A preliminary study of the influence of water potential on sclerotium germination in Sclerotinia sclerotiorum
Authors: Morrall R. A. A.
Published: September 2008

Sclerotia of Sclerotinia sclerotiorum (Lib.) de Bary buried in a heavy clay soil at 15 °C germinated over a range of moisture levels from 15% to 50%. A method of germinating sclerotia held at constant matric water potentials was tested. Sclerotia were placed in soil in bags of a semipermeable membrane; the bags were immersed in solutions of polyethylene glycol 20 000.Germination occurred between 0 and −7.5 bars but not at lower potentials.
Nonparasitic stunting of tobacco plants by Phytophthora cryptogea
Authors: Csinos Alex , Hendrix James W.
Published: September 2008

Burley tobacco plants were severely reduced in growth when transplanted into soils infested with nonviable Phytophthora cryptogea. Soils that were infested with the fungus and then sterilized by autoclaving or methyl bromide fumigation stunted tobacco transplanted into them. Mycelium produced on a defined medium and lyophilized, powdered, and mixed with soil was toxic to plants at between 0.5 and 1.0 g per 400 grams of soil. These results provide direct evidence that severe reduction in growth of Burley tobacco caused by P. cryptogea is not due to parasitism.
Anthopsis deltoidea, a new genus and species of Dematiaceae from soil
Authors: Marchisio Valeria Filipello , Fontana Anna , Mosca Anna Maria Luppi
Published: September 2008

Anthopsis deltoidea n.gen. et n.sp. of dematiaceous Hyphomycetes, isolated from horticultural soil in Italy, is described. The new fungus is characterized by a peculiar conidial apparatus and by triangular conidia.
Ultrastructure of wilt syndrome caused by Verticillium dahliae. III. Chronological symptom development in sunflower leaves
Authors: Robb Jane , Busch Lloyd , Brisson Jean D. , Lu B. C.
Published: September 2008

When sunflowers are infected by the vascular pathogen Verticillium dahliae, the first visible foliar symptom is the appearance of tiny chlorotic flecks. An attempt was made to determine the temporal order in which early ultrastructural changes leading to symptom expression occur. The evidence indicates that ultrastructural changes occur in the following order: (1) degradation of xylem vessel walls, (2) initiation of the necrotic band, (3) degeneration of the mesophyll tissue remote from the vein, and (4) degeneration of the phloem. The possible importance of xylem vessel plugs and of phenolic compounds to the initiation of symptom development is also discussed.
Mycoparasitic relationships. III. Parasitism of Physalospora obtuse by Calcarisporium parasiticum
Authors: Hoch H. C.
Published: September 2008

The host–parasite interaction between Physalospora obtusa and the biotrophic contact mycoparasite Calcarisporium parasiticum was studied by light and electron microscopy. After hyphal contact between the two fungi, a contact cell was delimited by a septum in the germ tube apex of C. parasiticum. Subsequently, a portion of the appressed walls of the host–parasite interface was dissolved, creating a large pore through which cytoplasmic exchange occurred. The results of this study explain, in part, how increased nutrient uptake from the host by the parasite is accomplished and dispells the hypothesis that the contact cell increases the permeability of the host plasmalemma to nutrients and required growth factors.
A membrane-bound plastid inclusion in the epidermis of leaves of Taraxacum officinale
Authors: Martin E. S. , Larbalestier G.
Published: September 2008

Epidermal chloroplasts of Taraxacum officinale agg. contain large electron-dense inclusion bodies enclosed by a single membrane. These inclusion bodies were not observed in mesophyll chloroplasts. The origin and functional role of these structures is discussed.
Transmission electron microscopy of annellides and conidiogenesis in the synnematal hyphomycete Trichurus spiralis
Authors: Hammill Terrence M.
Published: September 2008

This study was done to compare events of conidiogenesis with previous studies done on the closely related genera Doratomyces and Scopulariopsis. Formation of the first conidium by a T. spiralis annellide was not observed. Conidial initials blew out through the annellide apex, increased in size, and were eventually delimited by centripetally developing septa. Each conidial-delimiting septum subsequently split; the distal layer formed part of the conidial base, and the proximal layer became a portion of the wall of the next conidial initial. A circumscissile rupture of the wall layer continuous between conidium and annellide produced the characteristic annellations and conidial basal frills. Annellations on T. spiralis were more conspicuous than on the two species of Doratomyces and the two species of Scopulariopsis previously studied with electron microscopy. Differences in nuclear behavior and other differences and similarities among the five species were discussed. The term holoblastic to describe conidiogenesis in annellides was questioned.
The effects of substrate, temperature, and photoperiod on conidiationof Pyrenophora tritici-repentis
Authors: Platt Harold W. , Morrall R. A. A. , Gruen H. E.
Published: September 2008

Fifteen isolates of Pyrenophora tritici-repentis were used to determine the effects of substrate, temperature, and photoperiod on growth and conidiation. Conidiation was achieved with seven isolates when either 15% V-8 juice agar (1.5 g/l CaCO3 and 15 g/l agar) or autoclaved leaves of wheat or wheatgrass (Agropyron dasystachyum (Hook.) Scribn.) were used as substrates. However, V-8 juice agar provided the most consistent and abundant conidiation. Conidiophore production was observed over a temperature range of 10 to 31 °C while conidia were produced from 10 to 25 °C. Optimal conidiation on 15% V-8 juice agar occurred at about 21 °C. Twenty-five different photoperiods were tested and conidiophores were formed with all regimens containing alight period. Conidia were produced with 1 to 21 h of light (4790 lx) per day with an optimum at 12 ± 1 h at 21 °C on 15% V-8 juice agar.
The genus Sphagnum in Alberta
Authors: Vitt Dale H. , Andrus Richard E.
Published: September 2008

There are 21 species of the genus Sphagnum presently known from Alberta. A multiple-access key and an illustrated, dichotomous key are given for the species, and the habitat and distribution of each species in Alberta are presented. The species of sphagna that occur in the province have either widespread or continental tendencies in their distribution patterns. Oceanic and sub-oceanic species are absent from the flora.
Studies on lichen-dominated systems. XX. An examination of some aspects of the northern boreal lichen woodlands in Canada
Authors: Kershaw K. A.
Published: September 2008

The existence of two major types of lichen woodland in Canada, Cladonia stellaris woodland and Stereocaulon paschale woodland, is discussed in relation to their seral nature and their rarely developed theoretical climax type.Our own observations, coupled with previous descriptions from a wider area, suggest that Stereocaulon paschale woodland replaces Cladonia stellaris woodland in a more or less continuous zone from just west of Churchill across to Great Slave Lake, immediately north and south of latitude 60° N. Both woodland types are often typical of sandy soils (pH 6 or less) and almost always represent the final recovery phase after fire. Rarely, the lichen surface is replaced by a continuous moss cover as the spruce canopy closes. The lichen surface is thus dependent on the lack of competition from higher plants, the absence of which is characteristic of the climate of this northern boreal region. Cladonia stellaris woodland also occurs on palsas and peat plateaux where, again, lack of higher plant competition and a suitable pH exist.The recovery sequence after fire is a highly complex process and as yet only the following parameters have been categorized. In the early recovery phases, limited soil moisture and hence a reduced summer latent heat flux enhance the sensible heat flux. The surface conditions are analogous to those of a hot desert with very high surface temperatures and extremely large diurnal temperature fluctuations. The physiology of these initial moss and lichen colonizers presumably enables them to tolerate these harsh conditions. The establishment of a few spruce seedlings and the subsequent development of open lichen woodland modulates the harsh summer temperature regime and allows the further development of a vegetated surface. After humus accumulation, which acts as an effective mulch, summer soil moisture is elevated, enhancing the latent heat flux and correspondingly reducing the sensible heat flux. This probably allows the full development of mature lichen woodland with its almost monospecific ground cover of either Cladonia stellaris or Stereocaulon paschale. Limited data suggest that the net photosynthetic responses of these two species is favoured by the relatively warm mesic conditions established by the open spruce canopy. Good accumulation of snow in the winter is probably also important for protection of the lichen surface from low temperatures. The open nature of mature lichen woodland is apparently maintained by an active inhibition of spruce seedling establishment by the lichen mat, although the mechanism is not entirely clear.
Development of the epiphyllous appendages of Begonia hispida var. cucullifera: implications for comparative morphology
Authors: Sattler Rolf , Maier Uta
Published: September 2008

The epiphyllous appendages arise from the two outer cell layers of the young leaf by a cell division pattern like that of leaf inception at the shoot apex. The leaf-like appendages, especially, show a developmental pattern that resembles that of the main leaf. These data as well as anatomical evidence provide a factual basis for homologizing the leaf-like appendages with leaves (phyllomes). Only the position of the leaf-like epiphyllous appendages contradicts that of typical phyllomes. This contradiction disappears by applying the evolutionary process of spatial shifting (heterotopy) to leaves. This process leads to the formation of epiphyllous leaves which may be contrasted with cauline leaves. Since secondary appendages have been observed on some of the epiphyllous leaves, the concept of a 'leaf system' is used in contrast with the concept of ‘shoot system.’ In a leaf system leaves are interconnected without the intervention of a shoot apex. Supporting evidence from experimental research, especially organ culture, is pointed out. Other unusual modes of plant construction are briefly discussed.
The Alternaria brassicae – Nectria inventa host–parasite interface
Authors: Tsuneda A. , Skoropad W. P.
Published: September 2008

The Verticillium state of Nectria inventa is a destructive parasite of Alternaria brassicae. Tropic growth of parasite hyphae towards hyphae and conidia of A. brassicae occurs in the vicinity of the host. Upon contact, the parasite hyphae often form appressorium-like bodies on the host cells and produce fibrous adhesive material at the host–parasite interface. Conidia are penetrated more commonly than hyphae. Penetration of the septa in hyphae results in a separation of cells. Penetration of a mature conidium also occurs commonly at a septum. The presence of a large hole in the wall of the host cell and the meshwork of material at the penetration site suggest that enzymatic breakdown of host cell wall occurs. Juvenile conidia are penetrated usually at the basal pore.
Depolarization of cell membranes in leaves of Lycopersicon by extract containing Ricca's factor
Authors: Cheeseman John M. , Pickard Barbara G.
Published: September 2008

Extract containing Ricca's factor depolarizes the membrane potential of at least three types of cells in Lycopersicon leaves : mesophyll, midrib parenchyma, and midrib epidermis. The depolarization has been studied in some detail for the epidermal cells, in which depolarization appears to begin without a lag and is completed within 60–90 s. The maximum rate of depolarization is typically about 3 mV s−1. No changes in resistivity, capacivity, or intercellular electrical coupling have been detected during the depolarization.Extract from 0.5 mg fresh leaf tissue in 1 ml of water at pH 6.6 causes threshold depolarization in many experiments, and a concentration only 40 times greater is usually saturating. Raising the pH increases the concentration of factor required for saturation.With subsaturating concentrations of factor, the potential recovers somewhat after depolarization, and when factor-free medium is washed over the tissue the potential depolarizes briefly before returning to its baseline value. With saturating concentrations of factor, the potential depolarizes to an essentially stable level and no transient depolarization occurs when the factor is washed out.The potential remaining after application of a saturating concentration of factor is independent of the initial baseline potential but depends on the concentration of K+ in the equilibration medium and in the extract. The saturation level of depolarization is in the range of the Nernstian potential for K+, but whether it is precisely equal to the Nernstian potential for K+ has not been established.Evidently, the occurrence and influence of Ricca's factor should be taken into account in all electrophysiological studies of shoot tissue since the factor appears to be released whenever cells are wounded and may be released during other kinds of stress as well.
The reproduction and phenology of Antithamnion cruciatum (Rhodophyta: Ceramiaceae) in insular Newfoundland
Authors: Whittick Alan , Hooper Robert G.
Published: September 2008

Antithamnion cruciatum (C.Ag.) Näg. is reported from insular Newfoundland, its most northerly known location in North America. It exhibits a variable morphology occurring as the typical erect form, as a prostrate form, and as a fragmented form by which it perennates. Zonately divided sporangia containing four spores have been observed, but their function is unknown. Culture experiments show that the species grows at 10 °C and above, but fertility was not induced. Cytological studies indicate there is no genetic alternation of generations, and chromosome numbers suggest the population may be polyploid.
Genetic damage to a fern population growing in a polluted environment: segregation and description of gametophyte mutants
Authors: Klekowski Jr. Edward J. , Davis Edward L.
Published: September 2008

A population of the fern Osmunda regalis growing in a polluted river was investigated genetically. Previous studies documented a high frequency of postzygotically induced genetic and chromosome damage. This paper describes two categories of gametophytic mutants which occurred in the progeny of this population. A gametophyte phenotype which exhibited a maternal effect on the sporophyte generation when it was the female parent occurred in 7.8% of the spore sample. A gametophyte phenotype which could best be characterized as a neuter calluslike mass occurred in 6.6% of the spore sample. Studies of nearby O. regalis populations in non-polluted sites failed to document the presence of such phenotypes in the spore samples.
Cyanide-insensitive respiration in wheat: cultivar differences and effects of temperature, carbon dioxide, and oxygen
Authors: McCaig T. N. , Hill R. D.
Published: September 2008

The cyanide-insensitive respiration of the mitochondrial fraction isolated from etiolated coleoptiles of four cultivars of wheat has been studied under a variety of conditions. Cultivar differences were observed in the apparent capacity of the CN-insensitive pathway ranging from 8 to 35% of the observed state 3 respiration rate. Although Arrhenius plots of the state 3 and state 4 rates were relatively linear from 2.5 to 30 °C, the CN-insensitive oxygen uptake exhibited a distinct maximum rate at about 17.5 °C. Germination of the wheat in the presence of high concentrations of CO2 (15–25%) resulted in a dramatic increase in the capacity of the CN-insensitive pathway. Germination in 100% O2 appeared to have little effect on either the cytochrome or CN-insensitive electron-transport pathways. However, oxygen did exert a synergistic effect with CO2 since germination in 25% CO2 in oxygen yielded mitochondria with about twice the CN-insensitive capacity of wheat germinated in 25% CO2 in air.
Factors maintaining a disjunct community of Liatris spicata and other prairie species in Ontario, Canada
Authors: Roberts T. M. , Robson T. , Catling P. M.
Published: September 2008

Plants of the prairie peninsula have persisted in southwestern Ontario in localized areas where a high water table in spring, severe drought in midsummer, and intermittent burning have limited forest encroachment. Unlike these relicts of the postglacial xerothermic period, a community of prairie species on a railway embankment at West Hill (Toronto) has developed within the last 100 years. It is postulated that the persistence of these prairie species in the face of intense competition by seedlings from the surrounding fields is due largely to their adaptation to the seasonal fluctuation of moisture availability, nutrient deficiency, and periodic disturbance at this site. Mortality of invading seedlings was due to extrinsic environmental stresses rather than competition for limited resources during the period of active growth. The perennial Liatris spicata was able to dominate part of the habitat as a result of rapid growth of adults and seedlings before drought, low requirement for nutrients and effective mobilization from the corm in spring, and resorption before senescence. Experimental trials suggest that accumulation of litter, improving the moisture-retention and nutrient availability of the substrate, will lead eventually to elimination of Liatris and the other disjunct species. The case for preserving this community and other wet-mesic prairies in southwestern Ontario is outlined. However, it is clear that the current practice of 'conservation by complete protection' should be replaced by a management policy of periodic burning or mowing.
Seasonal periodicity in the discharge of Pucciniastrum goeppertianum basidiospores
Authors: Sickle G. A. Van
Published: September 2008

Discharge of Pucciniastrum goeppertianum (Kühn) Kleb. basidiospores from witches' brooms on lowbush blueberry (Vaccinium angustifolium Ait. and V. myrtilloides Michx.) in central New Brunswick occurred at irregular intervals from mid-May to late June in 1973 and 1974, but more than 75% of the total catch occurred in a 1-week period each year. Annual timings were related to spring weather variation so that discharge peaks each year coincided with shoot elongation of the aecial host, balsam fir (Abies balsamea (L.) Mill.). Measurable rainfall preceded all major discharge peaks; relative humidity and temperature were factors only as they affected the rate of drying of the hypertrophied twigs. Basidiospore concentration at 15, 90, and 150 cm above the ground level brooms decreased at a ratio of 7:2:1.
Miscellaneous microfungi. II.
Authors: Raj T. R. Nag
Published: September 2008

New taxa reported are as follows: Amphisphaeria argentinensis sp. nov.; Catenophora yuccae sp.nov.; and Hyphopolynema tropicale sp. nov., typifying Hyphopolynema gen. nov.
The ultrastructure of Polymyxa betae zoospore exit-tube differentiation
Authors: D'Ambra V. , Mutto S.
Published: September 2008

Zoosporangia of Polymyxa betae Keskin are plurilobate and develop cross walls. During ripening they show dark zones at the contact points with the host cell wall at the light microscope level. With the electron microscope these zones appear to correspond to single uninucleate compartments separated by a wall from the zoosporangium itself. These compartments give rise to exit tubes while the zoosporangial contents differentiate into zoospores. At the beginning of exit-tube formation, the thallus wall in contact with the host cell wall becomes thinner and softened. At the same time, thallus cytoplasm shows membrane-bound vesicles, the endoplasmic reticulum increases, and vacuoles enlarge. Vesicles are concentrated in the area of exit-tube formation and this suggests that they are involved both in host and thallus wall lysis. Wall microfibril profiles indicate that at this point mechanical forces have also been applied. A papilla, surrounded by a wall which appears to be continuous with the inner layer of the zoosporangium wall, is formed. The papilla elongates and becomes tubular, forming the zoospore exit tube. The same lytic and mechanical sequence described for thallus and host cell wall demolition at the site of exit-tube emission, also takes place in the demolition of zoosporangial cross walls.
Lack of reproducibility in bioassays for gene-specific RNA reportedly involved in the resistance response of wheat to stem rust
Authors: Rohringer R. , Howes N. K. , Kim W. K. , Samborski D. J.
Published: September 2008

Results published from this laboratory reporting evidence for a direct gene-specific effect of RNA in stem rust – wheat interactions could not be consistently repeated when an improved bioassay was used.
Effects of temperature on the photosynthesis–irradiance response curves of newly matured leaves of alfalfa
Authors: Ku S. B. , Hunt L. A.
Published: September 2008

Various carbon dioxide exchange characteristics are described for two alfalfa (Medicago sativa L.) genotypes (AT 171 and CC 120) grown at 20:15 °C and 30:25 °C day:night temperatures and 53 nE cm−2 s−1 irradiance (400–700 nm). Growth at 30:25 °C as compared with 20:15 °C resulted in lower net carbon dioxide exchange rates (NCE) for both genotypes when analyzed at 20 °C, but did not cause any sizeable change for CC 120 at 30 °C. Oxygen inhibition of photosynthesis increased with irradiance to 48 nE cm−2 s−1 but either declined or remained constant with further increase in irradiance. Oxygen inhibition was higher at 30 °C than at 20 °C and was not consistently influenced by growth temperature. However, the ratio of oxygen inhibition to carbon dioxide exchange rate in air containing 1% oxygen and the mesophyll resistance were greater with AT 171 grown at 30:25 °C than at 20:15 °C, particularly at high irradiances. NCE measured at 20 °C instead of 30 °C for plants grown at 30:25 °C was reduced to a much more marked extent with CC 120 than with AT 171; this difference was paralleled by a more marked increase in stomatal resistance length (rSL) for CC 120.rSL decreased with an increase in irradiance, was generally higher at 20 °C than at 30 °C, and did not differ between growth temperatures when measured at an irradiance of 116 nE cm−2 s−1 and a temperature equal to the day temperature of the growth regime. The results are discussed in relation to factors responsible for adaptability to different thermal environments.
The effects of soil factors on the distribution of Agrostis gigantea on a mine waste site
Authors: Hogan Gary D. , Courtin Gerald M. , Rauser Wilfried E.
Published: September 2008

A number of soils were examined from areas of a mine waste contaminated with heavy metals. Soils from areas vegetated with Agrostis gigantea Roth, which did not possess copper tolerance were compared with adjacent barren areas. Soils from sites which supported non-tolerant grasses had higher pHs and were lower in water-extractable metals than soils from non-vegetated areas. The soils did not differ with respect to any other factor examined. The non-vegetated soils were shown to be more toxic to the growth of Avena sativa than vegetated soils. The establishment and survival of grasses not having the selective advantage of copper tolerance were found to be restricted to the less toxic regions of the study site.
Copper tolerance in clones of Agrostis gigantea from a mine waste site
Authors: Hogan Gary D. , Courtin Gerard M. , Rauser Wilfried E.
Published: September 2008

A mine waste site from Sudbury, Ontario, contaminated with heavy metals is described. The dominant vegetative cover was formed by two grasses: Agrostis gigantea Roth, and Agrostis scabra Willd. Testing of 10 clones of A. gigantea from the roast bed and an adjoining area for copper tolerance showed that two clones collected from the roast bed were tolerant to increased copper levels. Copper tolerance was found in clones growing on soils with high copper contents and low pHs. The combination of high copper content and low pH brought about a high level of extractable copper within the soil. Soils with equally high copper levels but higher pHs and therefore low extractable-copper levels did not support copper-tolerant clones.
Ultrastructure of the epidermis and stomatal complex of balsam fir (Abies balsamea)
Authors: Chabot Jean Fincher , Chabot Brian F.
Published: September 2008

The ultrastructure of the epidermis and stomatal complex of Abies balsamea (balsam fir) was examined. Needles were fixed at the time of emergence from the bud and at intervals thereafter. Epidermal cells in the youngest needles examined had a prominent nucleus, with several nucleoli, ribosome-rich cytoplasm, a few rudimentary chloroplasts. and small vesicles with osmiophilic material. With maturation, the vacuole expanded to nearly fill the cell leaving only a thin layer of cytoplasm around the wall. The walls underwent a high degree of thickening, and a wax and cuticle layer developed.Guard cells were located below the needle surface with specialized subsidiary cells overarching them and creating a stomatal antechamber. This cavity contained wax formations deposited even before the needles emerged from the bud scales. Guard cells were substantially matured at the time of bud break with a characteristic pattern of wall structure. Chloroplasts, which develop multiple starch grains, were abundant near the polar ends of the cells. Radial micellation of the walls was pronounced. Specialized 'hinge' areas were noted. A region on the ventral wall, facing the pore, lacked lignification and showed distinct bends in the fibrillar material, which may be associated with opening and closing the stomate.
Floral organogenesis of Limnocharis flava
Authors: Sattler R. , Singh V.
Published: September 2008

Besides a trimerous calyx and corolla, the mature flower exhibits a polyandric androecium and an apocarpous gynoecium consisting of a whorl of carpels. Yet the primary pattern of the flower is completely trimerous and tetracyclic. After the inception of three sepals and three petals, three antesepalous primary androecial primordia are initiated each of which forms three stamens (i.e. secondary androecial primordia). Opposite these three groups of three stamen primordia, three groups of three carpels are initiated, possibly on three extremely inconspicuous primary gynoecial primordia. Additional carpel primordia are formed in varying numbers between the original three groups. Even before carpel inception, the three primary androecial primordia merge laterally thus forming an androecial ring. Additional stamen primordia arise on this ring first between the three groups of three stamen primordia and then in centrifugal direction as the androecial ring broadens basally. Eventually four whorls of stamens and two to three whorls of staminodia are formed secondarily on the androecial ring which arose from the primary primordia. Morphogenesis and construction of the flowers of Limnocharis flava differs in two major respects from those of all other taxa of the Alismatales studied thus far: (1) there are no stamen pairs primarily associated with the petals, and (2) the first-formed carpel primordia do not alternate with the stamen primordia of the preceding whorl, thus violating Hofmeister's rule of alternation.
Development of the inflorescence and flower of Sagittaria cuneata
Authors: Singh V. , Sattler R.
Published: September 2008

The reproductive region of Sagittaria cuneata is basically trimerous. This trimery is exhibited in the arrangement of the bracts, sepals, petals, pairs of stamens in the male flower, and pairs of staminodia in the female flower. In the male flower after the inception of three sepal primordia, each of the three petal primordia arises with one pair of stamen primordia on an alternisepalous bulge of the floral apex, i.e., a petal–stamen (CA) primordium. Subsequent stamen primordia are formed in alternation with the six first-formed primordia. If, for convenience sake, the first six primordia are referred to as the first whorl of stamens up to four additional whorls may be produced. Depending on the size of the floral bud, the third and fourth whorls (if present) consist of two to six stamen primordia, whereas the fifth whorl (if present) contains one to five stamen primordia. Finally, primordia of pistillodes are formed in varying numbers. In the female flower the presence of CA primordia could not be as clearly established as in the male flower. However, again each petal primordium is definitely associated with a pair of antepetalous primordia. The latter primordia develop into staminodia. In alternation with the first six staminodia six additional staminodia are formed and then again in alternation many whorls of pistils (carpels). Even in the mature flower the basic trimery is reflected in the triangular shape of the globose and massive gynoecium. From a developmental point of view, the male and female flowers are primarily trimerous. The polyandric androecium and the large pleiomerous gynoecium are superimposed on the primary trimery. It appears quite possible that this developmental modification also reflects a phylogenetic derivation. This means that the pleiomerous gynoecium and androecium are not primitive but rather advanced. There is no indication of a spiral arrangement of stamens and carpels.Whereas the foliage leaves, bracts, and sepals are initiated as dorsiventral primordia, the petals, stamens, staminodia, pistils, and pistillodes arise as more or less hemispherical mounds and become dorsiventral thereafter. The vegetative apices, inflorescence apices and the floral apices have a two-layered tunica over a massive corpus. Foliage leaves, bracts, sepals, petals, stamens, staminodia, carpels, and pistillodes are initiated by periclinal divisions in the second tunica layer. In the case of the stamens and staminodia the corpus may also contribute. Ovules are initiated by periclinal divisions of the second layer of the carpel primordium.
Floral development of Aponogeton natans and A. undulatus
Authors: Singh V. , Sattler R.
Published: September 2008

The primordia of the floral appendages are initiated in an acropetal succession. Members of the same whorl appear nearly simultaneously. The gynoecial whorl and the two staminal whorls are trimerous, whereas the perianth consists only of two anteriolateral tepals. However, the posterior (adaxial) tepal may be present as an extremely reduced buttress whose growth becomes arrested immediately after its inception. If this somewhat questionable tepal rudiment is included we have a perfectly trimerous and tetracyclic flower with alternation of successive whorls. Subtending bracts of the flowers are completely missing in all developmental stages. While the tepal primordia are dorsiventral from their inception, the stamen and pistil (carpel) primordia originate as hemispherical mounds which become dorsiventral in subsequent stages of development. Each pistil (carpel) primordium becomes horseshoe shaped. As the margins grow up and contact they fuse postgenitally. No cross zone is formed. Placentation is submarginal. In A. natans eight ovules are formed and in A. undulatus only two arise; all ovules are bitegmic. The floral apices have a two-layered tunica up to the stage of pistil formation. The inception of all floral appendages (including the ovules) occurs by periclinal cell division in the second tunica layer. The third layer (corpus) may contribute to the formation of the stamens and pistils. Each appendage primordium receives only one procambial strand which begins to differentiate after the inception of the primordium. The questionable rudimentary tepal buttress lacks a procambial strand. Apparently it does not reach the developmental stage at which procambial induction occurs. From the point of view of floral development, the two species of Aponogeton differ drastically from members of the Alismatales studied so far. Among the Helobiae, the Aponogetonaceae appear to be most closely related to the Scheuchzeriaceae and the Juncaginaceae (Triglochinaceae).
White pine blister rust: hypersensitive resistance in sugar pine
Authors: Kinloch Jr. Bohun B. , Littlefield Julia L.
Published: September 2008

Resistance to white pine blister rust in sugar pine is simply inherited and can be identified by distinct needle spot morphs. After artificial inoculation at 2 years of age, seedlings from selfed and full-sib families developed either 'fleck' spots, characterized by a pale, yellow margin with a necrotic fleck in the center, or they developed typical yellow or red spots (or both). Seedlings segregated for needle spot reaction in monohybrid ratios with fleck dominant. Mycelium in secondary needle tissues of fleck spots, in contrast to yellow and red spots, was relatively sparse and confined by dense tannin deposits. Bark infection and mortality was heavy on seedlings with yellow and red spots. On seedlings with fleck spots, no bark symptoms developed from secondary needle infection but small, abortive cankers did develop on some of these seedlings as a result of primary needle infection. These atypical cankers did not sporulate or spread extensively, and had healed by the 2nd year after inoculation. The gene responsible for the fleck reaction thus elicits a hypersensitive response in secondary needles and, apparently, in bark tissues as well.
Biosystematic studies in the genus Pholiota, stirps Adiposa
Authors: Farr Ellen R. , Miller Jr. Orson K. , Farr David F.
Published: September 2008

A study of the morphology and mating compatibility of a number of collections of Pholiota, stirps Adiposa A. H. Smith & Hesler, demonstrated that a species concept based upon interbreeding populations was broader than that of the morphological species currently recognized in the group. Pholiota abietis A. H. Smith & Hesler, P. connata A. H. Smith & Hesler, P. limonella (Pk.) Sacc, P. squarroso-adiposa Lange, and P. subvelutipes A. H. Smith & Hesler can be accommodated in the composite description of the eight interbreeding collections studied. Of these names, P. limonella has nomenclatural priority. Pholiota aurivella (Fr.) Kummer was found to be distinguished from P. limonella only by spore size.
A study of photosynthesis and leakage of solutes in relation to the desiccation effects in bryophytes
Authors: Gupta R. K.
Published: September 2008

Photosynthesis and the phenomenon of leakage have been studied in bryophytes Porella platyphylla (L.) Lindb., Plagiochila asplenioides (L.) Dum., Plagiothecium undulatum (Hedw.) B. & S., and Scapania undulata (L.) Dum. which were collected from habitats subjected to a wide range of moisture stresses. The percentage decrease in photosynthesis has been used as a measure of desiccation injury and the desiccation resistance has been denoted as number of days in which a particular injury level occurred. In all the species the rate of leakage reached the highest value in the first 2 min of re wetting, and the slowed down. Such reduction of leakage with time is believed to be due to the reassemblage of membrane structure, which results in a return of normal semipermeability, or to the rapid decrease of solutes in dead or injured tissues that occurs after rewetting. The solutes in the leachate are found to be reabsorbed by the viable cells. The leakage from viable tissues is likely to be due to the shock resulting from sudden immersion of desiccated shoots into water, while in injured or dead cells it is due to the disruption of membranes. The physiological and ecological implications of the leakage phenomenon are also briefly discussed.
Deuteromycetes. II. Antromycopsis broussonetiae
Authors: Moore Royall T.
Published: September 2008

Antromycopsis broussonetiae has recently been shown to be the appropriate form name for the coremia produced by Pleurotus cystidiosus and has been redescribed and figured by Pollack and Miller (Mem. N.Y. Bot. Gard. 28(1): 174–178, 1976). The present report represents the historical background and possible significance of the form species. That is, if A. broussonetiae is the status imperfectus of P. cystidiosus, then P. cystidiosus should occur in Algeria, the type locality of A. broussonetiae. The monokaryons of P. cystidiosus, when cultured, also produce coremia with an apical mucous spore drop. These, however, are smaller, as are the arthrospores. On the basis of descriptions and drawings it is suggested that A. broussonetiae subsp. minor Penzig & Saccardo may represent such monokaryotic coremia of P. cystidiosus; if so, then the anticipated range of P. cystidiosus is extended to India and Java. (Pleurotus cystidiosus was described from North America and has also been reported from South Africa and Taiwan.)
Seasonal growth and foliar nutrients of Larix laricina in three wetland ecosystems
Authors: Tilton Donald L.
Published: September 2008

Levels of N, P, Ca, Mg, K, Al, Fe, Zn, Mn, and B were determined in foliage from tamarack (Larix laricina (DuRoi) K. Koch) in a bog, conifer swamp, and fen from budbreak to leaf abscission. Elongation of needles and lateral shoots as well as dry and ash weight of needles were determined. Expansion of needles and shoots ceased at similar dates for all sites, but trees in the fen had significantly longer needles and lateral shoots.On August 13, foliar concentrations of N, Ca,and Mg were higher in the fen than in the conifer swamp or bog, while concentrations of Al, Fe, Zn, Mn, and B were higher in the bog than the other two sites. Phosphorus concentrations in foliage were similar on this date in the fen and conifer swamp but were lower in the bog site. Despite significant between-site variation for certain foliar elements, two patterns of seasonal variation in nutrient concentrations were discerned. Significant between-site differences in the amounts and rates of needle and shoot elongation, foliar nutrient concentrations at a single sampling time, and patterns of certain foliar elements were associated with variations in nutrient status and moisture–aeration conditions of the study sites.
Relative effectiveness of certain heavy metals in producing toxicity and symptoms of iron deficiency in barley
Authors: Agarwala S. C. , Bisht S. S. , Sharma C. P.
Published: September 2008

Excess supply of the heavy metals Mn, Cu, Zn, Co, and Ni to barley caused their accumulation in shoots and specially in roots and induced symptoms characteristic of the particular heavy metal involved, the syndrome of which varied with the different treatments. The effectiveness of the heavy metals in inducing visual symptoms was in the order of Ni2+ > Co2+ > Cu2+ > Mn2+ > Zn2+. These treatments caused a decrease in dry matter yield of plants in the order Ni2+ > Co2+ > Zn2+ > Mn2+ > Cu2+.Studies using 59Fe indicated that an excess supply of each of the heavy metals reduced iron absorption by plants and affected its distribution in roots and shoots. Excess of Co2+, Cu2+, Mn2+, and Zn2+ reduced iron translocation to shoots, induced chlorosis, and decreased catalase activity of young leaves. Excess nickel, which was most active in producing toxic effects, did not inhibit translocation of iron to young leaves. Unlike iron deficiency, an excess of Ni2+ did not decrease the activity of catalase and stimulated the activity of peroxidase. Excess supply of each of the heavy metals increased the concentration of non-reducing sugars. Observations suggest that toxicity to heavy metals does not necessarily involve induction of iron deficiency, their redox potentials, or the stability of their organometal complexes.
Development of long-shoot terminal buds of western white pine (Pinus monticola)
Authors: Owens John N. , Molder Marje
Published: September 2008

Long-shoot terminal bud (LSTB) development in western white pine (Pinus monticola Dougl.) was studied throughout the annual growth cycle to determine the phenology of LSTB development and the time of cone-bud differentiation. Development of LSTB began in early April and cataphylls were initiated from mid-August until early November. Cataphyll initiation was slow during May and June when shoots were elongating and then rapid just after shoot elongation was completed. Proximal cataphylls were sterile, whereas more distal cataphylls began to initiate axillary buds by late June or early July. Axillary buds were initiated first in the proximal portions of the LSTB and then acropetally in rapid succession. The last cataphylls to be initiated in the fall remained as sterile bud scales enclosing the LSTB apex. Axillary buds initiated sterile cataphylls which functioned as bud scales. The number varied with the type of axillary bud. Proximal axillary buds initiated few cataphylls and began to differentiate into dwarf shoots or pollen cones in August. The more distal axillary buds differentiated into dwarf shoots during September and October, The most distal axillary buds initiated many cataphylls during September and October but did not differentiate into seed-cone buds or lateral branch buds until after winter dormancy. Consequently, attempts to induce or enhance seed-cone production in P. monticola would probably be most successful in the spring when seed-cone buds differentiate. LSTB bearing seed cones were larger, had broader apices, and produced more cataphylls during the growing season than did LSTB bearing pollen cones. The phenology of LSTB development in soft pines and hard pines is discussed in relation to reports available on the association of cone crops and climatic conditions in several species of Pinus.
The effect of two organophosphate insecticides on the growth of freshwater algae
Authors: Birmingham Brendan C. , Colman Brian
Published: September 2008

Seven freshwater algae were grown in the presence of Abate® 4-E (O,O,O′,O′-tetramethyl-O,O′-thiodi-p-phenylene phosphorothioate) and Dursban® M-3633 (O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate) at 1,10, and 100 μg/ℓ active ingredient. The response of different algal groups to the insecticides was highly variable.The growth rate of the nitrogen-fixing blue-green alga Anabaena flos-aquae was increased from 22% at 10 μg/ℓ Abate to 58% at 100 μg/ℓ Abate when grown on nitrogen-free medium. Dursban caused similar growth stimulation. The green alga Chlamydomonas reinhardii showed growth stimulation in response to 100 μg/ℓ Dursban.Significant decreases in growth rate were observed for the green alga Chlorella pyrenoidosa after treatment with 10 μg/ℓ Abate (8%) and 100 μg/ℓ Dursban (12%). The diatom Navicula pelliculosa gave decreases in growth rate of the same order with 10 μg/ℓ Abate or Dursban.No significant effect on the growth rates of the diatom Navicula minima or the blue-green algae Coccochloris peniocystis, Oscillatoria sp., and Anabaena flos-aquae grown in the presence of nitrate was detected after treatment with either insecticide.
An investigation of photosynthetic sucrose production in bean leaves
Authors: Fry S. C. , Bidwell R. G. S.
Published: September 2008

First trifoliate leaves of wax beans. Phaseolus vulgaris, were exposed to 14CO2 in light for periods of 15 to 75 s. Leaves were frozen in liquid N2 and a chloroplast fraction was isolated nonaqueously. The chloroplast fraction contained a small amount of contaminating cytoplasm that could not be removed. Labelled photosynthetic compounds were separated from the whole leaves and from the corresponding chloroplast fractions and their radioactivity was measured.The compounds fell into two groups in their behaviour. Glyceric acid and ribulose, derived from photosynthetic 3-phosphoglyceric acid and ribulose diphosphate respectively, remained largely or exclusively in the chloroplast fraction. Labelled sucrose and serine and glycine, on the other hand, were located in the chloroplast fraction only during the first 15–30 s of 14CO2 supply, and appeared in the cytoplasmic fraction in increasing amounts thereafter. The results suggest that serine and glycine are produced in organelles in the layer of cytoplasm that closely surrounds the chloroplasts and is isolated with them in the non aqueous technique. Sucrose may also be synthesized from photosynthetic intermediates in this layer of cytoplasm. Sucrose was not formed from intermediates of the glycolate pathway in detached leaves.
Preliminary characterization of peroxidase isozymes isolated from two flax genotrophs
Authors: Fieldes M. A. , Deal C. L. , Tyson H.
Published: September 2008

Four peroxidase (EC 1.11.1.7) isozymes were isolated from each of two flax genotrophs. All four isozymes were glycoproteins and all exhibited indoleacetic acid (IAA) oxidase activity. The percentage purity of two of the isozymes was very high; these isozymes differed in percentage carbohydrate and in peroxidase and IAA oxidase specific activities. Three of the isozymes displayed molecular weight values of about 43 000; for the fourth, molecular weight was considerably higher. Corresponding isozymes from the genotrophs and from two other flax genotypes displayed molecular weight differences which corresponded to electrophoretic relative mobility differences. Enzyme yield per unit fresh weight was higher for one genotroph than the other, and the balance between peroxidase activity and IAA oxidase activity between the genotrophs was different.