bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental potentialities of leaf primordia of Osmunda cinnamomea. II. Further studies on the influence of determined leaf primordia on undetermined leaf primordia
Authors: Kuehnert Charles Carroll
Published: September 2008

In the fern Osmunda cinnamomea, leaf primordia may be excised and grown in sterile culture before or after their irreversible determination as leaves. It has been demonstrated that P3 primordia (third most recently formed primordia) are not irreversibly determined as leaves at the time of excision for they exhibit a tendency to develop as whole shoots (approximately 67.0% of the time) whether grown singly, or as pairs grown in physiological contact. Results from the present investigation support the hypothesis that a morphogenetic factor(s) is found in older primorida which is transmitted to younger primordia to influence the latter to develop as leaves rather than shoots, for P3's grown in physiological contact (as pairs) with P10, P12, or P13 primordia are expressed as leaves at a level approximately twofold or greater than P3's grown singly (controls). Results from the present investigation do not support the hypothesis that increased bulk of tissue, and therefore increased capacity for nutrient productivity by older and larger primordia, is responsible for imposition of leafness on undetermined P3 primordia, for P14 primordia grown in physiological contact with P3 primordia (as pairs) are observed to increase the percentage of P3's expressing leafness at a level only slightly greater than P3's grown singly, and slightly less than when P3's are grown in physiological contact with other P3's as pairs. The slight enhancement in leafness exhibited by undetermined P3's grown as pairs with other P3's, or with P14's has been shown to be non-significant at the 5% level (P < 0.05) by the standard t test and Kramer's (1956) modification of Duncan's (1955) new multiple range test.
Developmental potentialities of leaf primordia of Osmunda cinnamomea. III. Studies of the effects of homogenized, determined leaf primordia on expression-potential of undetermined leaf primordia
Authors: Kuehnert Charles Carroll
Published: September 2008

Further evidence is presented in support of the hypothesis that a morphogenetic factor, or factors, is present in older primordia which is transmitted to younger primordia to influence the latter to develop as leaves rather than shoots. P3 primordia, undetermined at the time of excision, are expressed as leaves at a level of 60.0% when explanted to a simple, defined medium containing, in addition, homogenate of determined P12 primordia and at a level of 70.0% when grown on medium containing homogenate of P13 primordia. By contrast, undetermined whole P3's are expressed as shoots approximately 70.0% of the time when excised and explanted to: (1) a homogenate-free medium, or (2) medium containing homogenate of undetermined P3's. Of greater significance is the observation that undetermined P3's are expressed as shoots at approximately the same level when excised and explanted to medium containing homogenate of determined P14 primordia. The relevance of these phenomena to a physiological aging process is briefly discussed.
Developmental potentialities of leaf primordia of Osmunda cinnamomea. IV. Expression-potential of undetermined primordia separated by a barrier membrane from undetermined or determined primordia
Authors: Kuehnert Charles Carroll
Published: September 2008

Undetermined P3 leaf primordia of the fern Osmunda cinnamomea were excised and grown in sterile culture, as pairs, with P12 or P13 primordia, primordia already irreversibly determined as leaves. Undetermined P3 primordia of a pair (P3 with P3 or P3 with P12) separated by an impervious barrier membrane (mica sheets) exhibit a tendency to develop as shoots rather than leaves. When the barrier membrane was a Millipore Filter, P3's growing with other P3's also exhibited the tendency to develop as shoots. By contrast, undetermined P3 primordia of a pair (P3 with P13) separated by a Millipore Filter barrier membrane exhibit the tendency to develop as leaves. These results would suggest that cell-to-cell contact is not a necessary adjunct to transmission of a leafness morphogen, and they present still further evidence in favor of a hypothesis that determination of a leaf primordium as a leaf may be under the control of more than one control center, and that one such control center is associated with certain of the older leaf primordia of a sibling series.
Total growth of a black spruce (Picea mariana) tree at Chalk River, Ontario, Canada
Authors: Fraser D. A. , McGuire D.
Published: September 2008

Apical and radial growth in trunk, branches, and roots, together with needle and cone distribution, were studied in a black spruce tree 31 years old and [Formula: see text] high. Growth of aerial parts was summarized as follows: (1) according to years of formation (oblique summation); (2) transversely on trunk inter-nodes (horizontal summation); and (3) according to the position of the annual rings, and the branch internodes (and needles) in relation to the pith or trunk (vertical summation). Root segments were classified on the basis of their diameter and distance from the trunk. Calculated on a dry-weight basis, the trunk accounted for 37%, the branches for 24%, the roots for 21%, and the needles for 18% of the grand total of 81 kg.The tree had 7.8 million needles when sampled in the fall of 1963, one-quarter of which were formed during the last 2 years of growth. Dry weight of individual needles varied with both position and age. While needles of the same season from the lower part of the crown exceeded those from the upper part in length, the reverse was true for the individual dry-weight content.In black spruce, cone periodicity, while distinct, is not as pronounced as in white spruce. The productive capacity of one "average" needle was estimated in terms of apical growth, trunk wood, and needle and root formation.
The role of the lodicule and epiblast in determining natural hybrids of Avena sativa × fatua in cultivated oats
Authors: Baum Bernard R.
Published: September 2008

Most reports on natural hybrids between A. sativa and A. fatua are not supported by definitive experimental evidence. Those authorities who have proved that natural hybrids do occur were assisted by the fact that both parents were known and occurred with the putative hybrids. The present study was conducted on samples of foundation plots from Canadian origin. Very useful characters were found in the lodicules and in the epiblasts which made it possible to detect F1 hybrids with precision in seeds of cultivated oats irrespective of their external morphologic markers. A hypothesis that the epiblast of the Fatua-type is dominant over the Sativa-type in F1 hybrids is set forth on the basis of the present findings. Higher frequencies of the Fatua-type epiblast were found in the samples where the lowest frequency of the Fatua-type lodicule was observed, because these samples were cultivars which had in their breeding history more crosses with A. byzantina than the others had. The importance of the lodicule and epiblast characters as markers is reassessed, and their reliability was reevaluated in view of the similarity of characters found in the epiblast of A. fatua and A. byzantina, and in view of the present findings. The taxonomic status of A. fatua and A. sativa is also discussed.
Taxonomy of Trifolium (Leguminosae). II. The T. longipes complex in North America
Authors: Gillett John M.
Published: September 2008

The taxonomy of the Trifolium longipes Nutt. complex (Leguminosae) in the western United States is reviewed. This polyploid complex consists of diploid, tetraploid, and hexaploid races having a base number of x = 8. For the most part, each race occupies a distinct geographical area. Keys to the three species recognized in this study and to the 11 subspecies of T. longipes in the restricted sense are provided. For each taxon a description and synonymy are given. Maps of the chromosome races and taxonomic entities are appended.
Fossil woods of Taxodiaceae from the Edmonton Formation (Upper Cretaceous) of Alberta
Authors: Ramanujam C. G. K. , Stewart Wilson N.
Published: September 2008

The paper deals with four species of taxodiaceous woods collected from the Edmonton Formation (Upper Cretaceous, Maestrichtian) of the Drumheller area in Alberta. Two of them are Taxodioxylon gypsaceum and Taxodioxylon taxodii, the former showing remarkable resemblances with the wood of modern Sequoia and the latter with Taxodium. Both species are being reported for the first time from the Upper Cretaceous of Alberta, Western Canada. The other two species are new and are named Taxodioxylon drumhellerense and Taxodioxylon antiquum. T. drumhellerense agrees particularly with the wood structure of Glyptostrobus. The xylem ray tissue of T. antiquum is characteristic in that the rays here are often extremely high (up to 90 cells) and locally as broad as three to four cells. Such high multiseriate rays are seldom encountered among the coniferous woods.
Ontogenetical and experimental studies of the floral apex of Portulaca grandiflora. 1. Histology of transformation of the shoot apex into the floral apex
Authors: Soetiarto Siti Raswati , Ball Ernest
Published: September 2008

The vegetative apex was a low dome consisting of two layers of tunica surmounting a very small corpus. Foliar primordia originated as periclines in the flanks of T2. The transition apex became first a steep cone and then a hemisphere. All floral primordia—the two bracts, the two sepals, the several whorls of petals, the several whorls of stamens, and the carpels—originated in the manner of leaves, as periclines in T2 on the flanks of the apex. All appendages, including carpels, were therefore lateral. In the early transition, the apex had a brief stage in which there were three tunica layers, but the inner one was lost with the onset of the sepals. The bracts and the first sepal continued the normal positions of primordia for the vegetative phyllotaxy of 3/8, but with the second sepal, this phyllotaxy was lost, and petals, stamens, and carpels were produced in whorls. While leaves, bracts, sepals, and petals were produced in acropetal sequence, stamens were produced in basipetal sequence, and carpels appeared simultaneously. After carpels were formed, the rest of the floral apex underwent a brief period of expansion growth, achieving a diameter comparable to that of a shoot apex, but its substance was eventually incorporated into the carpel margins, which later produced the ovules. This agrees with the determinate nature of the floral apex. During the development of the first series of floral organs, the floral apex underwent continued increase in area, finally achieving a diameter several times that of the vegetative shoot apex. Its size and form were such that they were compared to those of some inflorescence apices. After development of the first series of floral organs, the subjacent tissues to the floral meristem underwent divisions and elongation at right angles to the axis, causing at first a flattening of the meristem, and eventually a cup-shaped form, with the carpels attached in the bottom of a bowl. The mature flower was thus perigynous, but this development arose quite differently from the perigyny as it is known from ontogenetic studies in the Rosaceae.
Temperature and relative humidity regimes in the pine stump habitat of Fomes annosus
Authors: Schmidt Robert A. , Wood Francis A.
Published: September 2008

Temperature and relative humidity regimes in the stump habitat of Fomes annosus were characterized in a red pine plantation in Pennsylvania. Data were taken automatically at 2-h intervals around several stumps. A portion of these data from several periods of the year is presented.The measurement of temperature at four levels (soil, litter, stump-top, and ambient at 2-ft above the litter) around stumps showed that important differences existed among the separate levels at one stump, as well as among identical levels at separate stumps.Relative humidity, measured at two levels (sporophore locations and 2 ft above the litter) around stumps indicated that (i) a greater diurnal fluctuation and a generally lower relative humidity occurred at the 2-ft level, although few differences among stumps existed at this level; and (ii) the relative humidity at sporophore locations was comparatively high and varied with the position of the sporophore location on the stump, i.e., relative humidity adjacent to sporophores below the litter or in shaded niches was higher than those exposed to ambient conditions.Root and adjacent soil temperatures, measured at several levels beneath stumps, were similar for any one period except near the soil surface. Generally, the temperatures of the roots and soil increased with depth during outgoing radiation periods. However, the trend for incoming radiation periods varied with season, e.g., temperatures increased with depth in January and March and decreased with depth in July and October.The nature of these differences in fungus microclimate in the stump habitat varied with season, time of day, proximity of the soil surface, and the interaction of stand climate and vegetation. These differences indicate that temperature and relative humidity data intended for use in studies relating climatic factors and fungus activity should be measured as close to the site of interaction as possible.
Nutritional factors influencing the distribution of the calcareous and acidic populations in Hypericum perforatum
Authors: Ramakrishnan P. S.
Published: September 2008

Hypericum perforatum L. was found to have a wide range of distribution occurring on both calcareous and acidic sites. The two populations showed differential responses to macronutrients like calcium and phosphorus and micronutrients like aluminum and manganese. The acidic population showed better growth yield than the calcareous population at lower calcium levels in the medium, but at higher levels the reverse was true. The acidic population had higher uptake of calcium and phosphorus in all the different treatments and of magnesium, potassium, and sodium at low-calcium levels. The individuals of the calcareous population exhibited ‘phosphate toxicity’ at high phosphorus level in the medium while those of the acidic type gave better yield with increase in phosphorus level. Phosphorus uptake was consistently higher in the case of the acidic type compared to the calcareous population. The calcareous population was adversely affected at higher levels of aluminum and manganese and the individuals of this population exhibited severe toxicity symptoms. The acidic population gave good growth yield at both low and high levels of aluminum and manganese. The uptake of aluminum and manganese increased at higher levels of these nutrients in the media. These observations on the two populations have been discussed and it was concluded that besides the direct role of calcium, the differential response to phosphorus, aluminum, and manganese, the availability of which is determined by the pH of the soil, also control the restriction of the two ecotypes to their respective natural habitats.
Incomplete formation of cell walls in Allium epidermis
Authors: Haissig Karin , Stadelmann Eduard
Published: September 2008

Incomplete walls in upper epidermal cells of Allium cepa bulb scales were found in two out of three varieties tested. Various portions of longitudinal or transverse walls are missing or present only as rim-like wall fragments
Bryophytes of the aspen parkland of west-central Canada
Authors: Bird C. D.
Published: September 2008

One hundred and fifty-four taxa of bryophytes, including 15 hepatics, 2 peat mosses, and 137 mosses, are reported for the 255 000 km2 aspen parkland region of west-central Canada. Descriptions of the habitats and distribution of the individual taxa are given as well as species groups characteristic of the major habitat types. The following distributional elements are represented: Pan North American, 37%; Arctic–Boreal, 24%; Boreal, 21%; Eastern Boreal, 8%; Western Boreal, 1%; Cordilleran, 1%; Temperate, 5%; and Western Temperate, 1%. Only 3% of the taxa are endemic to North America.
Synonymy and pathogenicity of Dermea piceina
Authors: Smerlis E.
Published: September 2008

Synonymy of Dermea piceina Groves is established and pathogenicity of this species demonstrated on balsam fir (Abies balsamea (L.) Mill.) and black spruce (Picea mariana (Mill.) BSP.).
A new species of Lesquerella (Cruciferae) in northwestern Canada
Authors: Mulligan Gerald A. , Porsild A. E.
Published: September 2008

A new species of Lesquerella endemic to the Richardson and Ogilvie Mountains of northwestern Canada is described as Lesquerella Calderi Mulligan and Porsild. It is tetraploid with the base number x = 5 and is most closely related to Lesquerella arctica (Wormskj.) Watson, a widespread species of the Arctic that is dodecaploid with the base x = 5.
Diurnal shrinkage and swelling of tree stems
Authors: Sykes J. M. , Leyton L.
Published: September 2008

Experiments with dendrographs on trees of Japanese larch, Larix leptolepis (Sieb. & Zucc.) Gord., subjected to overlapping sawcuts, suggest that this treatment brings about a considerable change in the water status of conducting elements in the stem.
Laboratory culture of the intertidal brown alga Fucus vesiculosus
Authors: Fulcher R. Gary , McCully Margaret E.
Published: September 2008

Fucus vesiculosus L. plants have been grown successfully in a recirculating culture system which provides an intertidal environment.
Pathogenicity and taxonomy of Hypoxylon mammatum
Authors: French D. W. , Hodges Jr. C. S. , Froyd J. D.
Published: September 2008

Typical cankers with stromata were produced when aspen were inoculated with isolates of Hypoxylon mammatum (H. pruinatum) from aspen, but isolates from alder and willow were incapable of producing typical cankers on aspen. Isolates from willow produced cankers initially, but these were eventually callused over. Isolates from alder and aspen were not able to incite cankers on alder. Dimensions of the perithecia and ascospores of the fungus on aspen are not sufficiently different from those on birch, willow, and alder to justify maintaining H. pruinatum as a species separate from H. mammatum.
The ultrastructure of Olpidium brassicae. II. Zoospores
Authors: Temmink J. H. M. , Campbell R. N.
Published: September 2008

The ultrastructure of zoospores of Olpidium brassicae (Wor.) Dang. is described. The zoospores resemble other uniflagellate zoospores in many respects, but ribosomes occur throughout the zoospore body while mitochondria occur only around the nucleus. The axoneme seems to lack a terminal plate, and the rhizoplast differs markedly from that in other chytrid zoospores. The rhizoplast is a cross-banded structure that tapers from 350 mμ wide where it fits against the anterior end of the centriole and kinetosome to 150 mμ near the nucleus; its length is 1 μ. Some zoospores have two or three nuclei, and the origin of these zoospores is discussed.
Relation between photorespiration and glycolate oxidase activity in sunflower and red kidney bean leaves
Authors: Fock H. , Krotkov G.
Published: September 2008

Infrared gas analyzer techniques were used and the carbon dioxide gas exchange of attached red kidney bean and sunflower leaves was measured in an open gas stream. The glycolate oxidase activity of the leaf homogenates was manometrically determined. It was concluded that the maximal rates of photorespiration and glycolate oxidase activity have the same order of magnitude.
Comparative fungitoxicity and phytotoxicity of sodium N-methyldithiocarbamate and its n-alkyl homologues
Authors: Richardson L. T. , Thorn G. D.
Published: September 2008

A comparative study was made of the fungitoxic and phytotoxic properties of an homologous series of sodium N-alkyldithiocarbamates with 1 to 10 carbon atoms in the alkyl group. The ethyl, propyl, and butyl homologues were comparable to the methyl form (SMDC) in toxicity to Monilinia fructicola, while the amyl and hexyl were less active. A further increase in the carbon chain up to the decyl increased fungitoxicity correspondingly. Germination of barley seeds was inhibited progressively less from the methyl to the heptyl, slightly more by the octyl, and least by the decyl. None of the compounds had any apparent effect on tomato foliage at 10 mM, but when applied to cut stems of tomato or roots of tomato, barley, or cucumber many of the treatments induced wilting, leaf necrosis, and stem collapse. Quantitative data on both fungitoxic and phytotoxic effects were obtained from the emergence of peas planted in sand–vermiculite infested to various degrees with Pythium ultimum and drenched with a series of concentrations of each chemical. SMDC and the ethyl homologue were the most effective in controlling preemergence damping-off, the propyl through octyl progressively less effective, and the nonyl and decyl completely ineffective. Non-emergence due to chemical damage decreased from the methyl to the amyl homologue but increased from the octyl to the decyl.
Fungi on decaying leaves in marine habitats
Authors: Anastasiou C. J. , Churchland L. M.
Published: September 2008

Fourteen species of fungi are reported on submerged leaves of Prunus laurocerasus and Arbutus menziesii. Nowakowskiella elegans (Nowak.) Schroeter is reported from the ocean for the first time. Phytophthora vesicula sp. nov. is described and is reported to be extremely common on leaves in the marine environment. The relationship of P. vesicula to other species of the genus is discussed.
Terminal megasporangiate cones in pinyon pine
Authors: Lanner Ronald M.
Published: September 2008

Three megasporangiate cones apparently formed directly by shoot apical meristems were found in a terminal position on a pinyon pine (Pinus edulis Engelm.).
Studies of hypodermataceous needle diseases. II. Lirula brevispora sp. nov., causing needle blight of spruce
Authors: Ziller Wolf G.
Published: September 2008

A new pathogen of spruce (Picea spp.) needles is described. Although difficult to distinguish macroscopically from similar parasites, its short ascospores facilitate identification under the microscope. Its geographic distribution and importance as a cause of needle blight are still uncertain.
A comparison of the peroxidase isozymes of wheat plants grown at 6 °C and 20 °C
Authors: Roberts D. W. A.
Published: September 2008

The peroxidase isozymes from the first leaf of seven varieties of wheat of different levels of cold hardiness have been studied by agar gel electrophoresis. The plants were grown under controlled conditions at 6 °C or 20 °C. The isozyme pattern changes during ontogeny. The intensity of staining of the fastest moving "anionic" band is much greater in the leaves of the common wheats grown at 6 °C than in similar leaves from plants grown at 20 °C. This increase in peroxidase is apparently not associated with cold hardiness.
Biochemical mechanisms underlying the metabolic oscillations in yeast
Authors: Pye E. Kendall
Published: September 2008

Metabolic oscillations associated with the glycolytic pathway in intact cells and cell-free extracts of yeasts probably represent the first observation of prolonged self-sustained biochemical oscillations in vivo and in vitro. These oscillations have many characteristics similar to those of endogenous biorhythms which, others have postulated, might be driven by oscillations at the biochemical level. Among these characteristics are a stable frequency, a self-sustained nature, a susceptibility to phase shifting, fadeout, and reinitiation. The frequency is, however, temperature sensitive and high (approximately 1.8 minutes−1 in vivo and 0.17 minutes−1 in vitro).The metabolic oscillations, which represent a pulsing of the glycolytic flux, appear to arise by a mechanism involving an initial step of constant and specific velocity together with an activation of the enzyme phosphofructokinase by its product adenosine diphosphate. Other coupled reactions are also involved which may explain the appearance of "beats" and pulse-type oscillations, as well as the normal sinusoidal type of waveform. These oscillations are an interesting metabolic control phenomenon and allow the demonstration of apparent metabolic coupling between individual cells. They may also be useful as a model for a driving oscillation for endogenous biorthythms.
A hypothesis for extrinsic timing of circadian rhythms
Authors: Brown, Jr. F. A.
Published: September 2008

Circadian rhythms appear to be simply one type of component within a biogeosolunar rhythmic complex. The complex includes in addition to the solar-day ones, lunar-day (tidal), monthly, and annual rhythms which, like the circadian, may persist in constancy of all obvious environmental factors and display complete or nearly complete apparent temperature- and drug-independence. Steadily accumulating evidence suggests that this complex is widespread among plants and animals, perhaps omnipresent. Especially over the past 15 years, a number of kinds of newer observations on circadian rhythms have demanded for their explanation that information, including timing from the fluctuating external environment, be continuously available to the organisms exhibiting rhythmicity in the previously presumed shielded experimental conditions. An intensive investigation of the nature of this information has disclosed that organisms possess an extraordinarily specialized, receptive capacity for the natural geoelectromagnetic fields. Responsiveness to these fields has been demonstrated to be related to all the organismic geosolunar rhythmic components. Responses to such overt environmental factors as light and temperature have been shown, furthermore, to interact with the subtle geophysical responses in manners suggesting significance for biological clocks and compasses. Several of the properties of the subtle geophysical responses which have been uncovered, collectively now permit a rational explanation for the timing of circadian and other geosolunar rhythms without the classically postulated independent, intraorganismic "durational" timers for these periods. Organisms have been demonstrated to possess exactly that composite of capacities needed to enable them to use exogenous "coordinate" timing of circadian and other rhythmic physiological patterns.
Transducing mechanisms between circadian clock and overt rhythms in Gonyaulax
Authors: Sweeney Beatrice M.
Published: September 2008

In Gonyaulax polyedra it is possible to measure overt rhythms in luminescence, photosynthesis, and cell division. A common endogenous oscillator appears to control all three processes. The question of concern here is the manner in which the information regarding period and phase is transduced from oscillator to overt rhythm. In the rhythm of photosynthetic capacity, the path of electron flow through systems I and II appears not to be the site of transduction, since there is no rhythm in cells in flashing light, in the Hill reaction, or in sensitivity to such specific inhibitors as dichlorophenyl dimethyl urea (DCMU), and carbonyl cyanide m-chlorophenylhydrazone (CCmP). The probable site of control is in the Calvin cycle, since the activity of the first enzyme in this cycle, ribulose diphosphate dicarboxylase, varies with the phase of the cells from which the enzyme is derived. The low activity of this enzyme in crude extracts from cells in the night phase in continuous light can be overcome by increasing the concentration of bicarbonate in the reaction mixture. In vivo also, increasing the concentration of bicarbonate decreases the amplitude of the rhythm markedly. The activity of mixtures of extracts prepared during the day and the night phase is intermediate between that of either enzyme preparation alone, suggesting that the differences in activity are not caused by the presence of activators or inhibitors. The activity of ribulose diphosphate carboxylase is reduced by high temperature and by the presence of parachloromercuribenzonate (pCMB) and both adenosine triphosphate (ATP) and adenosine diphosphate (ADP), but differences in sensitivity to inhibitors between "day" and "night" enzyme preparations are not observed. The concentration of ATP extractable from cells does not vary with the phase of the rhythm.Transduction in the luminescent rhythm appears to be via changes in the mechanism by which luminescence is stimulated in vivo, since it is possible to obtain large and almost equal amounts of light from cells throughout the rhythmic cycle by the addition of acid. Eliciting luminescence in this way appears to bypass the normal mechanism of stimulation. This conclusion is strengthened by the observation that the inhibitory effect of light on cell luminescence is also eliminated when acid is used.
Reassessment of the genus Amblyosporium
Authors: Pirozynski K. A.
Published: September 2008

The name Amblyosporium spongiosum (Pers.) Hughes is adopted for A. botrytis auct. non Fres. A. botrytis Fres. is shown to be distinct. Searchomyces coprophiloides B. S. & M. D. Mehrotra, monotype species of Searchomyces, is transferred into Amblyosporium as A. coprophiloides (B. S. & M. D. Mehrotra) comb. nov., and a new species, A. thaxteri, is described.
Nitrogenous and carbohydrate compounds in the xylem sap of Ulmaceae species varying in resistance to Dutch elm disease
Authors: Singh Dilbagh , Smalley Eugene B.
Published: September 2008

Proline and γ-amino-n-butyric acid were present in considerable amounts in the sap of resistant species of the Ulmaceae such as Ulmus pumila, Hemiptelea davidii, and Celtis occidentalis, but occurred only in trace amounts in the sap of susceptible U. americana, U. japonica, and U. carpinifolia. The xylem sap of U. japonica, C. occidentalis, and H. davidii contained large amounts of alanine. Total concentrations of amino acids and ammonia were higher in resistant species than in susceptible species. Fructose, glucose, and sucrose were present in the sap of all the six species. Sucrose was the main sugar in the sap of U. japonica, U. pumila, and C. occidentalis; in U. americana and U. carpinifolia sucrose and fructose were present in about equal amounts; in H. davidii fructose was the major sugar.
Taxonomic studies on the genus Atrichum in North America
Authors: Ireland Robert R.
Published: September 2008

A taxonomic study was made of several North American taxa in the genus Atrichum. The primary emphasis was on the Canadian taxa and a key to the six species (A. altecristatum, A. angustatum, A. crispum, A. oerstedianum, A. selwynii, A. undulatum) and one variety (A. undulatum var. gracilisetum) of the country is presented. Atrichum oerstedianum, which has been confused with A. undulatum, is added to the moss flora of the United States and Canada. The distribution of A. crispum is clarified and a detailed study of the species revealed new morphological characters that are useful to distinguish it. A variety of A. undulatum, the var. altecristatum, is raised to the rank of a species and morphological and distributional data are given to support the status of A. selwynii as a distinct species. The first chromosome counts are reported for A. selwynii (n = 7) and A. altecristatum (n = 14). Detailed descriptions are provided for A. altecristatum, A. crispum, A. oerstedianum, and A. selwynii.
Some "black mildew", "sooty mold", and "fly speck" fungi and their hyperparasites from Dominica
Authors: Farr Marie L.
Published: September 2008

Forty-six fungi from Dominica, B.W.I., generally called "black mildews", "sooty molds", and "fly specks", and some of their hyperparasites, are listed, described, or discussed. The fungi belong in the families Meliolaceae, Atichiaceae, Microthyriaceae, Asterinaceae, Brefeldiellaceae, Micropeltaceae, Trichopeltaceae, Trichothyriaceae, Nectriaceae, and Dimeriaceae of the pyrenomycetes and in the families Sphaeropsidaceae, Peltasteraceae, Trichothallaceae, Dematiaceae, and Stilbellaceae of the Fungi Imperfecti. Meliola lobeliicola (Meliolaceae), Clypeolella palicoureae (Asterinaceae), Lembosia carludovicae (Asterinaceae), and Asterostomella diplocarpa (Peltasteraceae) are described as new species, and Meliola carludovicae var. setosa and Asterina melastomatis var. verrucospora as new varieties; Cicinnobella tropicale represents a new combination. A key to the three species of Clypeolella known on Rubiaceae is included.
Development of stomata in some Papilionaceae
Authors: Shah G. L. , Gopal B. V.
Published: September 2008

The ontogeny of stomata is described for 20 species of Papilionaceae. The mature stomata may be paracytic, anisocytic, anomocytic, diacytic, or with one subsidiary cell. The different types occur individually, or are placed side by side even on the same surface of the leaf. In many species the paracytic type is by far the most common, but in some anisocytic or anomocytic types are more frequent than the other types. The diverse types of stomata show mesogenous development. An increase in the number of subsidiary cells takes place either by their division, or by the neighboring perigenes assuming the form of subsidiary cells. Contiguous stomata are normally formed from two or more adjacent meristemoids. However, in Lathyrus sativus, in which they are frequent, their formation by "budding" has also been observed.
A reinvestigation of the morphology of the gametophyte and juvenile sporophyte of Ceratopteris thalictroides
Authors: Nayar B. K. , Kaur Surjit
Published: September 2008

The spores of Ceratopteris thalictroides are large (104 × 128 μ), trilete, with a costate exine and devoid of perine. At germination a rhizoid is produced at the proximal pole, followed by a short uniseriate germ filament lateral to it. Formation of a prothallial plate is initiated by longitudinal divisions in the intercalary cells of the germ filament, and soon a strap-like plate is developed. The thallus broadens and becomes spatulate, but is devoid of any meristem. A pluricellular meristem is later differentiated from lateral marginal cells on one side of the thallus away from the anterior region. The meristematic region becomes notched and later cordate. The anterior half of the thallus expands and develops into a broad flat wing while a smaller, often uplifted wing is developed posterior to the meristem. A midrib is formed behind the meristem when the prothalli are ca. 5 weeks old. The mature prothallus is devoid of trichomes, asymmetrically cordate, with a large, spreading wing and a smaller, often curled and cornucopia-shaped wing lifted up from the substratum. The midrib is thin and bears rhizoids and archegonia on the lower surface. Antheridia are restricted to the wings and are common marginally; they are embedded in the prothallial tissue, and consist of a central mass of spermatozoids surrounded by a basket-shaped, thin, basal cell, a narrow ring cell, and a solitary disk-shaped cap cell. The latter opens like a lid at antheridial dehiscence. The first wall formed in the antheridial initial is basket-shaped and the second wall is nearly flat. Development of the embryo is of the common type in leptosporangiate ferns. The first juvenile leaf is naked, with a spatulate lamina supplied by a solitary vein, and associated with the first root. One or two thick multicellular hairs are produced at the base of the second leaf and, in the succeeding leaves, these appendages are palea-like. A stem apex becomes evident usually only after the fourth leaf is developed. All early juvenile leaves are subsessile with entire lamina. The venation becomes reticulate in the second or third juvenile leaf. It is concluded that Ceratopteris is more closely allied to Anemia and Mohria than to other genera of ferns.
Extracellular production in relation to growth of four planktonic algae and of phytoplankton populations from Lake Ontario
Authors: Nalewajko C. , Marin L.
Published: September 2008

In four species of planktonic algae both carbon fixation and excretion on an ash-free dry weight basis increase with relative growth rate (K) of the culture measured in log10 units. In natural populations percentage excretion values are positively correlated with K values; however, environmental factors may be of relatively greater importance and determine the extent of excretion.
Development of the gibberellin-induced ovulate strobilus of western red cedar: quantitative requirement for long-day → short-day → long-day
Authors: Pharis R. P. , Morf W. , Owens J. N.
Published: September 2008

The induction of flowering in western red cedar (Thuja plicata Donn.) by gibberellin (GA3) has a quantitative requirement for long-day (LD). However, the strobilus does not develop fully under LD. Full development does occur though, if the photoperiod sequence of short-day (SD) → LD is given after an initial period of 3+ months under LD for induction. For the male, continued development entails a slight expansion and the shedding of pollen. For the female, it involves expansion from a tight 2-mm bud to a 15-mm cone, even without pollination. Cold increased the number of developing strobili, although it did not affect the date of first expansion. GA3 concentration had little effect on continued strobilus development under SD or LD. The present study indicates that continued development of the strobilus has a photoperiodic requirement that can be likened to the requirement of SD → LD of some flowers for anthesis. The requirement for SD is quantitative rather than qualitative, an increasing number of short-days will increase the number of expanding strobili, and eventually (18 to 30 months) some strobili will develop even under continuous LD. Continued development of the strobilus will not take place under SD alone, LD must follow. Therefore, the LD requirement in the sequence SD → LD appears to be qualitative in nature. This does not appear to be true for another conifer, Arizona cypress (Cupressus arizonica Greene). These strobili will develop under SD, but their development is enhanced by the sequence SD → LD.
The ultrastructure of Olpidium brassicae. III. Infection of host roots
Authors: Temmink J. H. M. , Campbell R. N.
Published: September 2008

As zoospores of Olpidium brassicae (Wor.) Dang. encyst on host root cells, they retract their axoneme, secrete a cyst wall, and form an adhesive substance that keeps them in place. The axonemal fibrils have been observed within young cysts but disappear later. The host cell forms a papillum that seems to be an inward extension of the host cell wall. In the cyst, a vacuole develops and enlarges while the cyst protoplast moves through the host wall via a central channel in the papillum, penetrates the host ectoplast, and establishes itself within the host cytoplasm. The ectoplast present around the cyst protoplast remains in the cyst, along with parts of the tonoplast, after infection is complete. This information permits evaluation of hypotheses concerning virus transmission by zoospores.
A study of factors influencing the genetics of reaction of barley to root rot caused by Helminthosporium sativum
Authors: Cohen E. , Helgason S. B. , McDonald W. C.
Published: September 2008

The inheritance of seedling reaction to root rot, caused by the 514 isolate of Helminthosporium sativum, was studied in crosses and backcrosses among the barley varieties CI.8969 and CI.8873, which show resistance, and the variety Olli, which is susceptible. The study was carried out under a controlled environment in growth cabinets. The data from reaction tests of F3 and backcross families were analyzed by Elston's procedure for testing a one-locus hypothesis, and by Powers' partitioning method. Polygenic inheritance for seedling reaction was indicated, but subsequent experiments showed that seed weight strongly influenced the reaction, which could account for the polygenic interpretation. Based on a drastic reduction of resistance in greenhouse-produced seed, irrespective of seed weight, a high positive correlation of seed weight with resistance in field-produced seed, and other evidence of a similar nature, it was assumed that resistance was related to a principle, present in the seed or on the seed surface, the quantity of which was influenced by seed size and modified by environment. Whether there was a genotypic influence on the quantity of the resistance principle, aside from that affecting seed weight, was not established conclusively. A field study involving the same materials, made in an area known to produce natural root-rot infection, showed that no correlation existed between the disease indices of the entries in the seedling stage in the growth-cabinet tests, and their reaction to the disease in the field. CI.8873 showed field resistance, whereas CI.8969 did not.
The biosystematics of Trillium rugelii from Rutherford County, North Carolina
Authors: Serota Cornelia Ann
Published: September 2008

A karyotypic and statistical study was made of samples from three populations of Trillium rugelii Rendle from Rutherford County, North Carolina. The data collected were compared with the karyotypes and statistics for Trillium flexipes Raf. (T. gleasoni Fern.) from western North Carolina and Tennessee, and for five members of the T. erectum L. complex. Trillium rugelii grows sympatrically with T. grandiftorum (Michx.) Salisb. and T. cuneatum Raf., two species which are morphologically dissimilar to it; but it is geographically isolated from T. flexipes and members of the T. erectum complex, the taxa which are morphologically most similar to it. The modal karyotypic comparison and the scatter diagrams correlate to show that this taxon is closely related to T. erectum var. album (Michx.) Pursh, T. simile Gleason, and probably to T. flexipes. There is evidence of distinct karyotypic variability among individual plants in T. rugelii. Although no chromosome types are peculiar to this taxon, there are no plant karyotypes (diploid sets) identical with those for T. rugelii among the seven taxa compared with it. Habit characters make this plant easily identified in the field. Taxonomic recognition for T. rugelii is justified. Further studies are required to determine to which rank it should be assigned.
Viability of Kabatiella caulivora
Authors: Berkenkamp B.
Published: September 2008

Kabatiella caulivora was examined under various cultural conditions, using tetrazolium as an assay of viability, and spore counts as a measure of growth. In liquid media growth and viability were favored by cool (15–20°) temperatures, acidic (pH 4) media, and use of spores before 10 days incubation, when autolysis began. Some isoflavones, present in red clover, were found to be inhibitory to the fungus. This is a factor in the inhibitory activity of certain red clover extracts.
Preuve de la viabilité des urédiniospores du Pucciniastrum agrimoniae après repos hivernal
Authors: Ouellette G. B.
Published: September 2008

The viability of overwintered urediniospores of Pucciniastrum agrimoniae (DC.) Tranz. was demonstrated through inoculations of agrimony plants under controlled conditions. Germination of these spores was also followed. Some of the spores formed a type of endospore, the germination of which was observed in a few cases.
Berkleasmium concinnum in culture
Authors: Goos R. D.
Published: September 2008

Growth of Berkleasmium concinnum in culture is described. Conidia germinated by the production of multiple germ tubes to produce restricted, compact, colonies which become covered after 15–20 days with a dense palisade of conidia. The conidia are aleuriospores that reach nearly mature size before septum formation is initiated.
Influence of peroxidase and catalases on mycelial growth and pycnidium production by Plenodomus meliloti in light and darkness
Authors: Zafar Saeed I. , Colotelo Nicholas
Published: September 2008

Mycelial colonies of Plenodomus meliloti Mark.-Let., incitant of brown root rot of legumes, were of similar size whether cultured in the light or in darkness on an agar medium. However, numerous pycnidia were produced only in the light. In the presence of 'active' horseradish peroxidase, beef liver catalase, and polyphenol oxidase enzymes, mycelial growth in comparison to controls was accelerated. Numerous pycnidia were produced in cultures incubated in light or darkness. When horseradish peroxidase and beef liver catalase were denatured by autoclaving, cultures were similar to controls. Aspergillus niger catalase inhibited mycelial growth and pycnidium production. Association of environmental conditions, peroxidase and catalase enzymes, and pathogenicity is discussed.
An antiviral principle from tomatoes systemically infected with tobacco mosaic virus
Authors: Chadha K. C. , MacNeill B. H.
Published: September 2008

An antiviral principle (AVP) has been isolated from tomato plants systemically infected with tobacco mosaic virus (TMV). This principle when mixed with TMV inoculum, or applied separately to the host before inoculation, markedly reduces the infectivity of the virus. Induction of the principle in tomato begins during the very early stages of virus–host interaction; later, with the development of a high level of AVP, there is a concomitant decline both in the amount of virus in the diseased plant and in the infectivity of the virus which is present. The production of AVP is not accompanied by overt signs of hypersensitivity or necrosis in the susceptible tomato host.
Comparative photosynthesis of red alder, Douglas-fir, Sitka spruce, and western hemlock seedlings
Authors: Krueger Kenneth W. , Ruth Robert H.
Published: September 2008

More rapid growth by red alder than by coastal conifer species may be explained by alder's greater foliage surface per unit foliage weight, greater total foliage area per seedling, and higher photosynthetic rate at high light intensities. Net photosynthetic rates per unit foliage area were similar for red alder and the three conifers up to saturating light intensity for the conifers. Relative weight of photosynthetic and nonphotosynthetic tissue was also similar for the four species. Average maximum photosynthetic rates measured for these conifers are comparable to reported rates for woody broad-leaved species.
Occurrence of silica in brown and green algae
Authors: Parker Bruce C.
Published: September 2008

Small but significant amounts of silica occur in all brown algae and green Hydrodictyaceae examined. At least in the hydrodictyaceous Pediastrum and Tetraëdron, the silica predominates in the cell wall. This silica is largely isotropic, non-crystalline opal with a small amount of α-quartz. Occurrence of silica in brown algae constitutes yet another feature suggesting phylogenetic relationships with the Chrysophycophyta, and the siliceous cell walls of the Hydrodictyaceae facilitate an understanding of both the nature of organic substances present and the process of zoosporogenesis.
An acetolysis-resistant membrane investing tapetum and sporogenous tissue in the anthers of certain Compositae
Authors: Heslop-Harrison J.
Published: September 2008

After the breakup of the meiotic tetrads, it is usual in the Compositae for the cells of the previously parietal tapetum to invade the anther loculus and form a Plasmodium ramifying between the young spores. In species of three tribes, Helenieae, Heliantheae, and Ambrosieae, an extratapetal membrane is formed at this time, which totally encloses the tapetum and the spore mass. The extratapetal membrane is resistant to acetolysis, and is considered to be chemically similar to the sporopollenin of the pollen grain exine.