Showing papers in "Botany in 1957"
TL;DR: The chromosome numbers of 58 Canadian weeds are reported and the significance of some of these chromosome numbers is discussed.
Abstract: The chromosome numbers of 58 Canadian weeds are reported. Counts obtained on material of Ambrosia psilostachya DC. and Epilobium angustifolium L. differ from those obtained by other workers. The chromosome numbers of the following species had not previously been reported: Silene cserei Baumg. 2n = 24; Axyris amaranthoides L. 2n = 18; Erigeron philadelphicus L. 2n = 18; Lepidium ramosissimum Nels. 2n = 64; Dracocephalum parviflorum Nutt. 2n = 14; Rumex fennicus Murb. 2n = 40; R. occidentalis Wats. 2n = ca. 140; R. stenophyllus Ledeb. 2n = 60. The significance of some of these chromosome numbers is discussed.
154 citations
TL;DR: Although the analytical data and the products of hydrolysis of the fractions indicate that complete resolution of the phosphatides has not been achieved, the methods described should be useful as a preliminary group fractionation, prior to fur...
Abstract: Methods are described for the extraction of total lipids (including pigments) from leaves, under conditions minimizing the action of phosphatidase C on the phosphatides, and for the fractionation o...
116 citations
TL;DR: The first leaves of resistant (Khapli) and susceptible (Little Club) species of wheat were heavily inoculated with stem rust and the INR/OR values suggest the operation of a Pasteur effect in uninfected tissue, and oxygen consumption per unit dry weight fell off after infection.
Abstract: The first leaves of resistant (Khapli) and susceptible (Little Club) species of wheat were heavily inoculated with stem rust (Race 15B). After infection, oxygen consumption per unit dry weight increased two- to three-fold and then fell off again. The R.Q. remained close to 1.0 until the respiratory peak was reached and then declined to 0.80 to 0.85, at least in Khapli. The INR/OR values (approximately 1.2) suggest the operation of a Pasteur effect in uninfected tissue. With infected tissue there was little or no increase in NR as oxygen uptake rose and the INR/OR values declined steadily to about 0.2 to 0.3. The oxygen uptake of rusted, mildewed, and uninfected tissue was stimulated by 2,4-dinitrophenol. The percentage stimulation was reduced by infection. The smallest percentage stimulations were observed, after the respiratory peak had been passed, with infected tissue of Khapli, in which chlorosis and other degenerative changes developed quickly. The actual increases in oxygen uptake obtained with 10−5...
87 citations
TL;DR: A re-examination of electro-osmosis and streaming potentials in xylem and phloem vessels suggests that the bio-electrical forces are sufficiently large in magnitude to cause transport and that they certainly operate in a direction to assist it.
Abstract: The background of bio-potentials in relation to transport is briefly reviewed and the chief difficulties lying in the way of an electrical theory of transport are pointed out. A re-examination of electro-osmosis and streaming potentials in xylem and phloem vessels suggests that the bio-electrical forces are sufficiently large in magnitude to cause transport and that they certainly operate in a direction to assist it. The productions of the potentials through metabolic activity and membrane diffusion is discussed.
65 citations
TL;DR: Minor variations in the water content pattern of yellow birch due to precipitation, evapotranspiration, and winter insolation lend little support to the view that birch dieback is due to an increase in temperature or to drought, except possibly through their effects on some unknown biotic factor.
Abstract: Complete seasonal patterns of moisture content of the wood and bark of Betula lutea (which resembles other species of birch) and of Tsuga canadensis are given, along with those for sapwood and hear...
63 citations
TL;DR: A new system of nomenclature is proposed with the purpose of presenting a scheme which will be applicable to spores, pollens, and other microfossils from all geological ages, and the applicability is illustrated by naming 21 new species and four new genera of Upper Cretaceous microf Fossils from the Comox formation of Vancouver Island and the Oldman formation of southern Alberta.
Abstract: A new system of nomenclature is proposed with the purpose of presenting a scheme which will be applicable to spores, pollens, and other microfossils from all geological ages. A review of previous nomenclatural systems is presented to indicate the historical development of microfossil nomenclature. The applicability of the new system is illustrated by naming 21 new species and four new genera of Upper Cretaceous microfossils from the Comox formation of Vancouver Island and the Oldman formation of southern Alberta. The microfossil conspecti are briefly compared with the assemblage previously reported from the Brazeau formation of western Alberta. Advantages of the new nomenclatural scheme are discussed in the light of future discoveries of plant microfossils, and their application to palaeobotanical and geological problems.
56 citations
TL;DR: A loose correlation was found to exist between toxin production and pathogenicity in a limited number of Helminthosporium strains, however, these strains differed in their ability to invade barley seedlings indicating that factors other than toxin production were also involved in Pathogenicity.
Abstract: The production of toxic substances by Helminthosporium sativum P.K. & B. on a variety of artificial media was evaluated by means of a barley seed germination test. The results suggest that these substances also limit the growth of the organism itself giving a fixed maximum level of toxin production. Destruction of toxin and renewed production continue until some other factor of the medium limits further growth, and culture filtrates then rapidly become inactive. The toxins are relatively nonspecific and appear to affect susceptible hosts by conditioning them to invasion by the organism. A loose correlation was found to exist between toxin production and pathogenicity in a limited number of Helminthosporium strains. Even in the presence of abundant toxin, however, these strains differed in their ability to invade barley seedlings indicating that factors other than toxin production were also involved in pathogenicity.
54 citations
TL;DR: Analysis of internodal wood volume growth into its three linear components leads to the conclusion that the determinants in control of wood growth act mainly through their effect upon apical activity and upon specific increment of cambial area.
Abstract: Two measures are needed to describe numerically the activity of the internodal cambium in terms of annual increment. These are "specific wood volume increment", a measure of additive growth and "sp...
51 citations
TL;DR: Karyotypic analysis of the chromosome complements of the section Capillares revealed that in the basic diploid set of 2n = 18 chromosomes four units are long, 10 are medium and abouthalf the length of the long ones, while four are small and about half the lengthof the medium ones.
Abstract: The small section Capillares of the genus Carex has been studied from the cytological and taxonomical points of view. It comprises nine distinct species, one of which (C. Boecheriana) is raised to specific status in this paper. Three species include two distinct subspecies each; two varieties and three formae are accepted for two species respectively. The chromosome numbers of the taxa involved are 2n = 18, 36, 38, 40, 54, 56, and 58. It is pointed out that the chromosomes of Carex have a polycentric or diffuse kinetochore and that this explains the aneuploid variations in number known to be typical of the genus. Karyotypic analysis of the chromosome complements of the section Capillares revealed that in the basic diploid set of 2n = 18 chromosomes four units are long, 10 are medium and about half the length of the long ones, while four are small and about half the length of the medium ones. This frequency of size classes is also met with in the plants with 2n = 36 and 54 chromosomes. Those taxa with 2n =...
47 citations
TL;DR: It is shown that all indigenous and forage grasses constitute a reservoir of ergot inoculum for rye, wheat, and barley, and that these cereals can be infected provided the environmental conditions are such that inoculum will be disseminated at the time that the cereal crops are in blossom.
Abstract: Four hundred and twenty-one isolates of Claviceps purpurea from 38 different host species were cultured on an artificial medium. The conidial cultures were used to inoculate rye, wheat, and barley growing in the greenhouse. All cultures, except one from Glyceria borealis, infected the three host species. Honeydew from rye was used to inoculate 46 gramineous species in the field and in the greenhouse. Every one of these grasses became infected in both locations. It is shown that all indigenous and forage grasses constitute a reservoir of ergot inoculum for rye, wheat, and barley, and that these cereals can be infected provided the environmental conditions are such that inoculum will be disseminated at the time that the cereal crops are in blossom.
45 citations
TL;DR: Seeds of Zostera marina L. are shed in Prince Edward Island waters during mid to late summer and germinate the following spring, and can be found in nature before winter.
Abstract: Seeds of Zostera marina L. are shed in Prince Edward Island waters during mid to late summer and germinate the following spring. Occasionally seeds germinate in nature before winter; they can be germinated during autumn and winter in the laboratory. Elongation of cells of the cotyledon and doubled-back axial hypocotyl pushes the embryo out of the seed coat. Cell increase plays no part in this or subsequent elongation of cotyledon and hypocotyl. Leaves emerge through the slit-like opening at the top of the cotyledonary sheath. Hairs develop from cells of the convex surface of the basal swollen hypocotyl; two adventitious roots grow from the cotyledonary node, develop root hairs, and anchor the seedling. Stelar tissues of the hypocotyl and cotyledon differentiate at germination. No characteristically thickened tracheary elements differentiate in hypocotyl or cotyledon. In the hypocotyl, phloem differentiates around the central xylem parenchyma and abuts externally on endodermis which develops Casparian stri...
TL;DR: When glucose-C14 or fructose-C 14 were used the radioactivity in the stem decreased logarithmically from the point of introduction and the downward translocation of both sugars was impeded at the nodes.
Abstract: Glucose-C14, fructose-C14, or sucrose-C14 were introduced into soybean seedlings through the cut petiole of one primary leaf. After 3 to 15 minutes the distribution of C14 throughout the plants was determined. Each of the three sugars was translocated as such without conversion to other compounds. Translocation was mainly downward from the point of introduction into the stem. Very little sugar was translocated to the primary leaf opposite the treated petiole or to the growing tip of the stem. Of the small amount of sugar that was translocated upward the bulk accumulated in the younger rather than the older trifoliate leaf.When glucose-C14 or fructose-C14 were used the radioactivity in the stem decreased logarithmically from the point of introduction. The downward translocation of both sugars was impeded at the nodes. Translocation was not inhibited by 10−2 M potassium cyanide. These hexoses were translocated both upward and downward past killed sections of stems. When sucrose-C14 was used the radioactivit...
TL;DR: The fusiform cambial cells of conifers undergo two types of anticlinal division, pseudotransverse division and division to produce small cells off the side, both of which are infrequent and seem generally to involve only thefusiform initials.
Abstract: The fusiform cambial cells of conifers undergo two types of anticlinal division, pseudotransverse division and division to produce small cells off the side. Pseudotransverse divisions are largely c...
TL;DR: Pollen tubes required about 4 days to grow from stigma to ovule and in some plants, particularly bagged ones, nucellar cells remained aliv...
Abstract: Seed development was followed from fertilization to maturity. Pollen tubes required about 4 days to grow from stigma to ovule. In some plants, particularly bagged ones, nucellar cells remained aliv...
TL;DR: Six races of Plasmodiophora brassicae Wor.
Abstract: Six races of Plasmodiophora brassicae Wor. have been distinguished on the basis of pathogenicity on differential hosts of cultivated and wild crucifers.Pathogenic differences between isolates were ...
TL;DR: The products of photosynthesis of two marine flagellates have been examined and compared with those of Chlorella pyrenoidosa with the use of radioactive carbon and chromatographic techniques.
Abstract: The products of photosynthesis of two marine flagellates have been examined and compared with those of Chlorella pyrenoidosa with the use of radioactive carbon and chromatographic techniques. The a...
TL;DR: Development of Zostera marina L. is described from proembryo to mature seed and develops into a swollen basal part and an elongated axial part formed by cell divisions at the base of the cotyledon and plumule.
Abstract: Development of Zostera marina L. is described from proembryo to mature seed. The single cotyledon and the stem apex develop laterally from the nearly spherical young embryo. No radicle is produced; the hypocotyl develops into a swollen basal part (the original embryonic mass) and an elongated axial part formed by cell divisions at the base of the cotyledon and plumule. The cotyledon grows in part by cell divisions at its apex. Curvature develops in the axial hypocotyl mainly by unequal elongation of cells, whereas curvature of the cotyledon is mainly by unequal increase in cell numbers. A single procambial strand differentiates from the suspensor end of the basal part of the hypocotyl through the axial part into the cotyledon and plumule. The plumular stem apex develops a single-layered tunica over a several-layered corpus. It produces three leaf primordia, one with air-spaces organized, before dormancy sets in. Mid-vein procambium differentiates acropetally from the axial strand into each leaf primordium...
TL;DR: A method involving the use of a detergent and boron has been developed for the introduction of C14-labelled sugars into leaves and it was found that more C14 from photosynthate accumulated in the growing stem tip than in the root.
Abstract: A method involving the use of a detergent and boron has been developed for the introduction of C14-labelled sugars into leaves. This method was used for translocation studies.In the light, transloc...
TL;DR: Evidence suggests that Astragalus should be subdivided, and consideration is given to the phylogeny of AStragalus.
Abstract: Chromosome counts have; been obtained for 71 collections; seven tribes, 11 genera, and 39 species of the Leguminosae are represented. Pollen mother cells were collected in the field and examined in acetocarmine. Twenty of the species studied were in the tribe Galegeae: Astragalus 14 species, Oxytropis five species, and Glycyrrhiza one species. Twenty-nine of the counts have not been published before. Consideration is given to the phylogeny of Astragalus. Evidence suggests that Astragalus should be subdivided.
TL;DR: Walls of elongating parenchyma and epidermal cells of Avena coleoptiles and onion roots were studied by autoradiography, using C14-labelled sugars, and by electron microscopy of thin transverse sections, showing a marked change in wall structure as elongation proceeds.
Abstract: Walls of elongating parenchyma and epidermal cells of Avena coleoptiles and onion roots were studied by autoradiography, using C14-labelled sugars, and by electron microscopy of thin transverse sections. The autoradiographs showed that deposition of cellulose takes place over the whole length of the cell, ruling out the possibility of bipolar tip growth. Autoradiographs of cells grown for short times in labelled sugar gave no evidence of localized incorporation of isotope around primary pit-fields, but rather indicated that deposition of microfibrils is finely dispersed over the entire wall surface. The thin sections revealed a marked change in wall structure as elongation proceeds. Walls of young cells contain only transversely oriented microfibrils while older walls include an inner region of predominately transversely oriented microfibrils bounded outside by a region with microfibrils showing an irregular transition to longitudinal orientation. The degree of longitudinal orientation in the outer region...
TL;DR: The species, found in nature on dung of various herbivorous animals (rabbit, deer, and cow), is culturable, growing more consistently on V-8 vegetable juice agar than on other media tried, most vigorously in association with other fungi like Aspergillus repens or Microascus sordidus.
Abstract: An emended description of Sphaeronaemella fimicola Marchal refers this species to its proper taxonomic position among the Hypocreaceae, with both perfect and imperfect stages very similar to those of S. helvellae Karsten as described by Seeler. The species, found in nature on dung of various herbivorous animals (rabbit, deer, and cow), is culturable, growing more consistently on V-8 vegetable juice agar than on other media tried, most vigorously in association with other fungi like Aspergillus repens or Microascus sordidus, or with addition of filter-sterilized Czapek's broth in which A. repens had been grown. Fruiting in culture has been erratic; only early transfers from isolations made from field material yielded mature perithecia in pure culture, and then only on V-8 agar; later transfers fruited only in intimate contact with the mycelia of the other two fungi mentioned.
TL;DR: It was ascertained that the species from which Grimm alfalfa presumably originated, viz.
Abstract: It was ascertained that the species from which Grimm alfalfa presumably originated, viz.; Medicago sativa and M. falcata, may freely exchange genetic material without evidence of a sterility barrier. Consequently a polyhaploid obtained of Grimm may be considered as comparable to natural diploids.The polyhaploid showed some impaired morphological and physiological characters and pronounced meiotic abnormalities. The single genome (x = 8) of the polyhaploid was found to be almost non-functional. Inheritance of purple color indicated a potential autotetraploid mode of transmission of characters.The polyhaploid was raised back to the tetraploid chromosome level by chromosome doubling and compared to its original and to Grimm. The somatically chromosome-doubled counterpart was found to be a close replica of the original polyhaploid. An assumption that an accumulation of detrimental recessive genes may remain latent at the tetraploid level, and may be expressed upon later reduction to half of the genic variabil...
TL;DR: The phosphatide content of primary leaves of runner bean increased linearly with time, between the 8th and 20th day of development, at a rate proportional to the growth of the leaves.
Abstract: The phosphatide content of primary leaves of runner bean increased linearly with time, between the 8th and 20th day of development, at a rate proportional to the growth of the leaves.Detached leave...
TL;DR: The inheritance of coumarin in white blossom sweet clover was determined from a study of crosses involving plants of the variety Arctic, Pioneer, and cou marin-deficient selections.
Abstract: The inheritance of coumarin in white blossom sweet clover was determined from a study of crosses involving plants of the variety Arctic (containing free coumarin). Pioneer (containing bound coumarin), and coumarin-deficient selections. Both a flurometric and a colorimeter test were used to detect the presence and type of coumarin.Among high-coumarin plants, variation in the amount of coumarin was due to non-heritable causes or genetic factors not detected in this study. The cross of free-coumarin × bound-coumarin plants established that the bound-coumarin character was inherited as a simple recessive. The gene symbol b is proposed for this character. In the crosses of high-coumarin × coumarin-deficient plants the F1 progeny were more or less intermediate in coumarin content and the subsequent F2 established that coumarin production is governed by one partially dominant gene. The symbol Cu is proposed for this gene. The gene B, responsible for the free-coumarin production, expresses itself only in the pres...
TL;DR: Comparative studies were made on the morphology of herbarium specimens and plot-grown plants of three species of Elymus L. in Ledeb, namely, E. racemosus Lam.
Abstract: Comparative studies were made on the morphology of herbarium specimens and plot-grown plants of three species of Elymus L. in section Psammelymus Griseb. in Ledeb., namely, E. racemosus Lam., E. ar...
TL;DR: It was concluded that the toxins inhibit enzyme activity by affecting the integrity of the mitochondria allowing diffusion of cytochrome c from active sites.
Abstract: The presence of an active cyclophorase system capable of oxidizing the principal acids of the Krebs acid cycle was demonstrated in mitochondria from hypocotyls and cotyledons of tomato seedlings. T...
TL;DR: Fifteen groups, comprising 106 substances, were studied for their effect on the germination of conidia of Helminthosporium sativum Pamm.
Abstract: Fifteen groups, comprising 106 substances, were studied for their effect on the germination of conidia of Helminthosporium sativum Pamm., King and Bakke in soil. Spores usually germinated when substances from groups composed of natural products were included in the substrate. Of these substances, wheat germ, bran, certain oil meals, molasses, orange juice, and green plant tissues were very effective, whereas refined flours and commercial sugars were only slightly so. When wheat straw and roots of wheat plants were added to the soil the conidia did not germinate. In contrast to the above-mentioned groups, most of the substances in the acid, salt, vitamin, protein, amino acid, oil, saccharide, plant hormone, and miscellaneous groups were not effective. The exceptions in these groups were ascorbic acid, galactose, and raffinose.
TL;DR: Four new species of Chlamydomonas are described, including C. mexicana, C. philotes, and C. ulvaensis, which were isolated from soil and found to be heterothallic.
Abstract: Four new species of Chlamydomonas are described. C. euryale was isolated from sea water; C. mexicana, C. philotes, and C. ulvaensis were isolated from soil. C. mexicana is heterothallic. and C. philotes homothallic.
TL;DR: Tests on 26 heterothallic species of Hymenomycetes have shown that Lenzites abietina (Bull. ex Fr.) Fr.
Abstract: Tests on 26 heterothallic species of Hymenomycetes have shown that Lenzites abietina (Bull ex Fr) Fr, Odontia uda (Fr) Bres, Peniophora phlebioides Jackson & Dearden, Phlebia merismoides Fr,
TL;DR: In coniferous stems the rate of multiplication of fusiform initials in the vascular cambium by means of pseudotransverse division often fluctuates considerably around the circumference and this is indicated by the decided increase in rate in areas of the stem subjected to radial pressure.
Abstract: In coniferous stems the rate of multiplication of fusiform initials in the vascular cambium by means of pseudotransverse division often fluctuates considerably around the circumference. In fluted stems the frequency of these divisions is appreciably higher and the ratio of survival of the newly formed initials relative to the rate of production lower in the depressions than in the adjoining convex portions of the perimeter. The probability that compression is a factor tending to accelerate the frequency of anticlinal division is indicated by the decided increase in rate in areas of the stem subjected to radial pressure. Higher frequencies of pseudotransverse division are accompanied by reduction in mean cell length of the cambial cells and hence of the derived wood elements.