Showing papers in "Botany in 1961"

A preliminary study of differential pollen grain preservation

Abstract: Samples of pollen of three genera (Populus, Pinus, and Typha) which are normally shed at different times during the growing season were placed concurrently in four habitats (a pond, a lake, a swamp, and a bog). Their decomposition was traced through the summer and autumn of two seasons. The study shows that there is considerable variability in fossilization of pollen under identical conditions, and that the decomposition of the same pollen is dependent on the habitat, which affects not only the rate of decomposition but also the processes involved.

Dormancy studies in seed of avena fatua: 2. a gibberellin-sensitive inhibitory mechanism in the embryo

Abstract: Natural inhibition of germination in A. fatua L. involves restriction of both sugar accumulation and utilization of sugar in growth. Both these metabolic blocks are independently overcome by exogenous gibberellic acid (GA). Evidence has been found for the presence of a natural gibberellin in seeds of A. fatua L. The control of dormancy is probably by a gibberellin-inhibitor antagonism since at least one inhibitor has been shown to intervene specifically in sugar production and this latter effect can be reversed by GA. The evidence presented here supports the view that control of germination during the period of after-ripening is through changes in inhibitor content rather than in endogenous gibberellin.

The formation of pinosylvin and its monomethyl ether in the sapwood of pinus resinosa ait.

Abstract: Mechanical damage to bark and cambium of red pine (Pinus resinosa Ait.), as well as fungal penetration of sapwood in the interior of roots and stems, induces the formation of heartwood substances in the affected parts of the sapwood. Paper chromatography disclosed the occurrence of pinosylvin (trans-3,5-dihydroxy-stilbene) and its monomethyl ether (3-hydroxy-5-methoxy-stilbene) in affected sapwood. Normal undamaged sapwood does not contain these substances, which were found to be restricted to the heartwood, except for pinosylvin monomethyl ether, which was found to occur also in the pith of branches.Field and laboratory experiments were carried out on the local formation of pinosylvins in the sapwood of live branches of red pine following wounding of the cambium. It was found that the pinosylvins are formed in the late part of the growing season and during the dormant season. Cross sections through the wound on branches showed the pinosylvins in a triangular pattern with the wounded cambium as a base lin...

Translocation of c14 in tobacco at different stages of development following assimilation of c14o2 by a single leaf

Abstract: Single leaves of tobacco plants at four different stages of development were allowed to carry on photosynthesis in C14O2 for 30 to 50 minutes followed by photosynthesis in air. The total elapsed time from the beginning of assimilation was hours. Redistribution of C14 was determined in: I, a young plant with eight leaves; II, an older plant with 19 leaves; III, a mature flowering plant with 29 leaves; IV, a mature seed plant with 35 leaves. The leaf treated with C14O2 in each of the four plants was number seven, counting from the bottom. This leaf was only half expanded in the youngest plant but fully expanded in the other three plants.The treated leaf of the youngest plant translocated 22% of the total C14 fixed, twice as much as the treated leaves of the other three plants. The large amount of translocation in the youngest plant occurred from a leaf that contained 28% of its ethanol-soluble fraction as sugar phosphates and only 25% as sucrose. The treated leaves of the older plants that translocated half...

The metabolism of urea and ureides

Abstract: Urea has long been of interest to both plant and animal physiologists. As early as 1889 De Vries demonstrated by plasmolytic methods that urea permeates plant cells. Since then it has played a larg...

The leptographium complex. phialocephala gen. nov.

Abstract: Some Leptographium-like hyphomycetes are maintained as distinct from that genus on the basis of spore ontogeny, and a new genus, Phialocephala, erected for them

The physiology of host–parasite relations: vii. the effect of stem rust on the nitrogen and amino acids in wheat leaves

Abstract: The dry weight of leaf disks (2.8 mm in diameter) bearing pustules of stem rust and cut from primary leaves of Little Club wheat increased up to 2.5-fold, but the respective weights of host and parasite cannot be measured. By removal of the ectoparasitic mycelium of Erysiphe it was shown that approximately half of the increase in weight at infections of this organism on barley leaves was contributed by the fungus and half by the host.At infections of stem rust on Little Club there was a striking increase in total N per gram fresh weight and an increase in the ratio of soluble to insoluble N. Quantitative paper chromatographic analyses revealed a fourfold increase in free amino acids and nearly a twofold increase in protein amino acids per gram fresh weight by 9 days after inoculation. The most striking increases occurred in free glutamine, γ-aminobutyric acid, threonine, and those amino acids present only in trace amounts before inoculation, particularly the basic and aromatic acids. Only slight and trans...

Critique of some vegetational concepts as applied to forests of northwestern alberta

Abstract: The application, by R. Plochmann, of certain European silvicultural and ecological concepts in the study and description of forests of northwestern Alberta is examined. His ideas of unidirectional succession to the single climax forest are criticized on the grounds that concepts such as succession and climax must always be related to specific terrain. Every forest community, and indeed every vegetational community, is the botanical part of a unique geographic ecosystem which gives it meaning, and it is neglect of the geographic framework which has led to the false assumptions that forest communities can be studied as things-in-themselves, and that vegetational concepts derived in one region can be transplanted unchanged to others.

The botany of the northwestern queen elizabeth islands

Abstract: Ellef Ringnes Island has a confirmed flora of 49 vascular plants and five parasitic fungi. The adjacent islands have less diversity of habitat and probably have even poorer floras. There are no endemics and the plants are extremely depauperate. The summer climate at Isachsen is colder than at any other station in the Canadian arctic. Although there are no convincing indications that Ellef Ringnes I. was overrun by a Wisconsin continental ice sheet, it cannot have escaped being snow-covered. The light cover of snow and ice on the outer islands was quickly lost in the postglacial xerothermic, which enabled plants to spread along the periphery of the archipelago. The numerous plants that occur south-west and northeast of these islands but not in them indicate that postglacial cold periods, probably accompanied by at least partial snow cover of the outermost islands, have driven out many species. Nearctic refugia are discussed and it is indicated, by analysis of distribution patterns, that no refugia occurred...

Botanical studies on mont st. hilaire, rouvillecounty, quebec: general description of the area and a floristic survey

Abstract: The Monteregian Hills are a series of eight mountains, intrusive in nature, which form a distinct petrographical province in the St. Lawrence Lowlands of Southern Quebec. Mont St. Hilaire, one of t...

Taxonomy, morphology, and pathogenicity of rhizoctonia species from forest nurseries

Abstract: The history of the concept of the genus Rhizoctonia is reviewed. Ten species and one variety of Rhizoctonia were identified from the study of over 60 selected isolates obtained from the forest nurs...

Studies of coprophilous ascomycetes vii. preussia

Abstract: The Plectascales and Perisporiales are both artificial taxa each consisting of a miscellaneous assemblage of unrelated genera. The generic name Perisporium is not valid for species of Ascomycota (Ascomycetes). The valid name for those species which produce ascocarps is Preussia Fuckel. The ascocarps are non-ostiolate (cleistothecia) and their development is the same as that in the Loculo-ascomycetes (producing a pseudothecium). The ascocarp of Preussia is thus a cleistothecial pseudothecium. The genus most closely related to Preussia is Sporormia and the two may be included in the same family Sporormiaceae. Preussia is not included in the Phaeotrichaceae on account of the elongated germinal slit and lack of hairs on the peridium of the ascocarp. Twelve species are included with descriptions and illustrations. The type species of Preussia is P. funiculata Fuckel. Three species are transferred to this genus from Perisporium. These are P. punctata (Auersw.) Sacc., P. typharum Sacc, and P. vulgare Corda. One ...

New species of the genus ceratocystis

Abstract: A study of the species of Ceratocystis found in Ontario on decaying slash has been made and most of the species grown in pure culture. The characteristics of the genus and the separation of species are discussed. Four species found on wood of coniferous trees are described as new. Illustrations are included for all of these. Ceratocystis brunneocrinita Wright and Cain is described from several collections of Abies balsamea. The perithecia have brown ostiolar hyphae and the ascospores appear rectangular. Ceratocystis europhioides Wright and Cain, on Pinus and Picea, has ascospores similar to but larger than the nonostiolate Europhium trinacriforme Parker. Ceratocystis falcata Wright and Cain, on Pinus, resembles Ceratocystis minuta (Siem.) Hunt but is distinguished by the longer, septate ascospores. Ceratocystis sagmatospora Wright and Cain, on Pinus and Picea, has saddle-shaped ascospores with elaborate gelatinous sheaths.

The genus microascus

Abstract: Descriptions are given of 14 species of Microascus. M. pyramidus Barron and Gilman is described as a new species and M. trigonosporus var. macrosporus Orr as a new variety. The conidial stage and c...

Evolution of carbon dioxide by tobacco leaves during the dark period following illumination with light of different intensities

Abstract: Detached tobacco leaves were placed in a closed-circuit apparatus and the air was continuously circulated over the leaves and through an infrared CO2 analyzer. From the known volume of the apparatus and the percentage of carbon dioxide in its air, the amounts of carbon dioxide either absorbed or evolved by a leaf were calculated.When, after a period of illumination, leaves were darkened, the attainment of their steady rates of respiration was preceded by two outbursts of carbon dioxide evolution. Since these outbursts occurred only after a period of illumination, it has been concluded that both were the result of photostimulation. The peak of the first outburst was usually considerably higher than that of the second. It was of short duration and the height of its peak was accentuated by the increased light intensity in the preceding light period. The second outburst lasted longer and prior light intensity had no effect on the height of its peak.

Modified incompatibility of buckwheat following irradiation

Abstract: Among plants grown from buckwheat "seeds" which had been exposed to X rays or thermal neutrons two thrum-flowered plants each had a branch bearing modified flowers. One thrum plant had a branch bearing homostyled flowers and the other a branch bearing pin flowers. A thrum plant in the progeny of the latter plant was self-fertile, produced no progeny in crosses with other thrum plants, but was fertile in crosses with pin-flowered plants. These cases are discussed in relation to a postulated S supergene controlling incompatibility in buckwheat.

Heterophylly in hippuris, a problem in identification

Abstract: Although the primordia of all types of leaves in Hippuris show no distinguishing characteristics until they are 50 microns long, their further development is strongly influenced by their environment. At maturity they can, for convenience, be thought of as belonging to one of five types, or some intermediate of these types. The five types of leaves are: rhizome, juvenile aquatic, adult aquatic, juvenile aerial, and adult aerial. Field and experimental studies indicate that the leaf form in Hippuris is influenced by light and the water relations between the plant and its environment. There is great uniformity of foliar morphology on plants from stocks of diverse origin when grown under uniform conditions, and there is wide diversity of foliar morphology on plants of the same stock material when grown under different environments in the laboratory. Thus the taxonomic subdivision of genus Hippuris into species, varieties, and forms using leaf morphology as the main criterion appears questionable.

A closed-circuit apparatus with an infrared co2 analyzer and a geiger tube for continuous measurement of co2 exchange in photosynthesis and respiration

Abstract: An apparatus is described which permits continuous monitoring of the concentration of both the total and radioactive carbon dioxide around an experimental plant. The apparatus consists of a closed ...

The sporulation of helminthosporium oryzae as affected by exposure to near ultraviolet radiation and dark periods

Abstract: Investigated was the interrelation of near ultraviolet radiation (3100–4000 A) and darkness to the sporulation of Helminthosporium oryzae. When H. oryzae was grown on potato dextrose agar at 70–75° F and irradiated at intensities of 76–470 μw per cm2: (1) Near ultraviolet stimulated sporulation while visible light did not. (2) Conidiophore development was initiated under irradiation but not in darkness. Both continuous irradiation and intermittent irradiation (2-hour ultraviolet, 2-hour dark cycle) caused formation of conidiophores. (3) Conidia developed only when a period of irradiation was followed by a period of darkness. No conidia developed under continuous irradiation or in continuous darkness. (4) Under a single cycle treatment, the minimum dark period necessary for conidial development following an extended period of continuous irradiation was hours. (5) Under a single cycle treatment, the minimum exposure to ultraviolet followed by an extended dark period necessary to cause moderate to profuse co...

The effects of photoperiod, temperature, and light intensity on the growth of the lowbush blueberry (vaccinium angustifolium ait.)

Abstract: A study of the effect of environmental factors on the growth and development of the lowbush blueberry was carried out using clonally propagated plants. In a preliminary study a definite photoperiod...

Ribonuclease activity in rusted wheat leaves

Abstract: Extracts from primary leaves of Lee wheat were prepared at various days following inoculation with races of leaf rust and tested for ribonuclease (RNase) activity. As early as 24 hours after inoculation there was a marked increase in the specific activity of the enzyme in extracts of rusted host tissues. A further increase in activity was observed during later stages of infection, with the susceptible and resistant reacting tissue differing only in the degree of their response. Extracts from noninoculated control leaves exhibited a constant RNase activity throughout the period of observation. The germination medium and extracts from germinating uredospores contained comparatively little RNase activity. No direct evidence was obtained either for the possible release of the enzyme from particulate cellular fractions of the host tissue as a result of infection or for the removal of an RNase inhibitor in the host tissue responding to infection.

FURTHER EVIDENCE OF THE RELATION BETWEEN 2-DESVINYL-2-FORMYL-CHLOROPHYLL-a AND CHLOROPHYLL-d

Abstract: 2-Desvinyl-2-formyl-chlorophyll-a (made by permanganate oxidation of chlorophyll-a) and chlorophyll-d (isolated from Gigartina papillata) were compared. They possessed identical visible absorption ...

Growth and morphogenesis in the canadian forest species: iv. radial growth in branches and main axis of pinus resinosa ait. under conditions of open growth, suppression, and release

Abstract: The analysis of growth of a pine tree has been extended to include the primary branches, and this paper reports observations on radial growth, as expressed by ring width.Trees from contrasting situ...

Grouping of isolates of a low-temperature basidiomycete on the basis of cultural behavior and pathogenicity

Abstract: Isolates of an unidentified low-temperature basidiomycete, associated with snow mold in Western Canada, were divided into three types, A, B, and C, on the basis of their general cultural appearance...

Studies of soil fungi: iii. new species of coniochaeta, chaetomidium, and thielavia

Abstract: Descriptions and illustrations are given for three new species of Ascomycetes having colored, one-celled ascospores and isolated from forest soil by J. H. Warcup. Coniochaeta tetraspora Cain sp. nov. has dark spiny hairs on the perithecium. The phialospores and blastospores are typical of the genus. The soil from which it was isolated came from Queensland, Australia. Chaetomidium minutum Cain sp. nov. has short, curved hairs on the globose, nonostiolate perithecia. The soil sample came from N. Queensland, Australia. Thielavia variospora Cain sp. nov. has black, nonostiolate, bare perithecia and was isolated from soil collected in New Guinea.

The genus ascodesmis

Abstract: A study of the physiological, cytological, and morphological characteristics of four species of the genus Ascodesinis has been made. The genus represents a highly specialized coprophilous group of the operculate discomycetes, probably belonging to the Humariaceae. A new specific name (Ascodesmis sphaerospora nom. nov.) and a new species (Ascodesmis macrospora sp. nov.) are proposed.

Changes in the dry weight, protein, nucleic acid, and chlorophyll contents of growing pea leaves

Abstract: Pea leaves of different ages were harvested over a 10-day growth period and were analyzed for the following: fresh weight, dry weight, cell number, chlorophyll, soluble protein, ribonucleic acid, and deoxyribonucleic acid. The chlorophyll content increased rapidly during early leaf expansion, then remained fairly constant. Only small differences were found in the percentage of soluble protein in the leaves during their development. In contrast, the ribonucleic acid and deoxyribonucleic acid levels in the leaves decreased continuously as the leaves aged. These results are discussed in relation to similar analyses performed on leaves from other higher plants.

Some effects of potassium deficiency on the metabolism of the tomato plant

Abstract: The organic and keto acid levels in the leaves of tomato plants grown with varying levels of potassium were examined. As the potassium level was reduced, the levels of malic, oxalic, and sometimes ...