17,858 research outputs found

    Investigations on the ecology and production-biology of the "floating meadows" (Paspalo-Echinochloetum) on the Middle Amazon. Part 1: The floating vegetation and its ecology

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    Investigations on the "floating meadows" (Paspalo-Echinochloetum) of the vârzea- region of central Amazonia in the surroundings of Manaus were made from May 1967 until October 1968. The ecology of the dominating species Pasþalum reþens BERG, Pasþalum fasciculatum WILLD., Echinocltloa þoþstaclqta (H. B. K.) HITCCHKOCK, Leersia ltexandra Swart (Fam. Gramineae) and diverse subsidiary species (Oryza þerennis Moench, Hymeachne amþlexicaalis (Rudge) Nens, Panicum chloroticum Nens (.Fam. Gramineae), Scirþus cubensis Poepp Kunth. (Fam. Cyperaceae) etc., was studied in details. Regarding Pasþalum reþens Berg, various floating and one terrestrial forms of growth were observed. Further, quantitative investigations on primary production and the development of populations of this species were made. As shown by 4 Pasþalum reþens- populations which were growing under different environmental conditions, conclusions on age and rapidity of growth of the population could be drawn from the relation between quantity of stems and number of shoots. The preliminary conditions for a "secondary colonization" of floating populations by non-floating plants and the repercussions of such sort of colonization on the primary populations are discussed. The vârzea-waters are subdivided into 3 biotopes with regard to the floating vegetation, and the factors responsible for them are discussed: l) Bank- and sedimentation-zones in the Solimões-Amazon. Dominating species: Pasþalumfasciculatum, Pasþalum reþens, Echinocltloa poþstaclgta, 2) Vârzea lakes with high fluctuations of water level. Dominating species: Pasþalum fasciculatum, Pasþalum. reþens, Echinocltloa þoþstachya. Sometimes, however, as well all other mentioned species occur in masses. Biotope richest in species. 3) Várzea lakes with relatively little fluçtuations of water level. Dominating species: Leersia hexandra, Scirþus cubensis, Pasþalum reþens. Both the current-region of the Solimões-Amazon as a biotope of its own and the influence of black-water on the vegetation are discussed

    The distribution of growth in a maize leaf : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Botany at Massey University

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    The extension in a maize leaf phytomer was studied in terms of the one dimensional displacement of its fabric relative to its base as a function of position and of age. The relationship between displacement, position and age was termed the displacement field. The displacements, during a 24 hour interval, of a series of points spaced along the length of a particular phytomer was recorded. This provided an Eulerian evaluation of the 24 hour displacement field. A population of plants each representing a different age were used and the average displacement field of the phytomer during its period of growth was established. Extension was localised in the region named the growth zone at the base of the phytomer. The length of the growth zone rose and fell following a wave shaped curve with respect to age. It was never constant. The relationship between the displacement of and position of points within the growth zone formed a smooth sigmoid curve. The presence of the ligule and of the node of leaf insertion did not give rise to any local reduction in extension. A method of tracing the movement of a point in the leaf fabric, through the growth zone, over a period of time is explained. Such Lagrangian pathlines are described using referential notation, X=x(t;x.). The pathlines of points were constructed by a stepwise addition of the relevant displacement values read from the displacement field for each successive position and age. The pathlines of two chosen points provided positions, as a function of age, for the boundaries of a growing and moving segment. The segment was in mid lamina. Its length increased from 0.025mm when its lower boundary was at 3.6mm from the leaf base to 2mm at maturity. The numbers by types of cells in the lower epidermis of the segment were surveyed at a series of plant ages. There was an initial decrease and then a considerable increase in the average length of the non stomata! cells during the period of the experiment. During the same period the segment increased in length and this was accompanied by an increase in the number of cells in the sample rows. This increase in cell numbers was continuing when the segment reached a position 40mm from the base of the leaf within the then 67mm long growth zone. The associated cell division was occurring in all of the cell categories, not the stomata! complexes alone. The development of stomata with respect to plant age is discussed. Stomata! initiation in the leaf segment was not restricted to a single occasion or unique position in the growth zone

    Dos nuevas especies de Andropogon (Poaceae, Panicoideae) de Cuba

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    Two new species of Andropogon (Poaceae) from Cuba, A. ekmanii and A. canaliglumis, are described and illustrated. Both belong to the ¨A. lateralis¨ species complex (sect. Leptopogon Stapf) and are the first members of this complex endemic to the West IndiesDos nuevas especies de Andropogon (Poaceae) de Cuba, A. ekmanii y A. canaliglumis, son descritas e ilustradas. Ambas pertenecen al complejo ¨A. lateralis¨ (sect. Leptopogon Stapf) y son los primeros miembros del complejo endémicos de las Antillas OccidentalesFil: Norrmann, Guillermo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Swenson, Ulf. SwedishSwedish Museum of Natural History, Estocolmo; SueciaFil: Caponio, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin

    The sedges and grasses of Gautambudhnagar (Noida) U.P. India

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    The present study is the result of two years (April 2005-April 2007) of extensive survey and exploration of sedges and grasses of Gautambudh Nagar. A total number of 95 species of Cyperaceae and Gramineae (Poaceae) have been collected from this area. Out of 95 species of these two families belonging to 68 genera, 65 species belong to Gramineae (Poaceae) and 30 species belong to Cyperaceae. There are two plants of Cyperaceae and Gramineae (Poaceae) respectively: Eleocharis capitata R. Br. and Isachne albens Trin., which have been reported for the first time from this area

    VULPIA (GRAMINEAE) IN MALESIA

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    SUMADIJAYA, A. & VELDKAMP, J. F.2009. Vulpia (Gramineae) in Malesia. Reinwardtia 12(5): 343–346.- A brief account of Vulpia (Gramineae) in Malesia is which consisting of V. bromoides and V. myuros is provided here, based on material seenprimarily by JFV in BO, K, L, CANB

    Atmospheric pollen dynamics in Malaga (s. Spain) during 2013-2014. Seasonal trends

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    In this work we present the atmospheric pollen results obtained in Malaga, a coastal Mediterranean city situated in southern Spain, throughout 2013 and 2014. The main objective is to compare the results obtained these years with those registered during the 21 previous years (1992-2012) and detect possible significant trends. The samplings were made with the aid of a Hirst-type volumetric pollen trap (Hirst, 1952) situated on the roof of the building of the Faculty of Sciences, Campus de Teatinos. The mounting of the samples and the pollen counting were according to the methodology proposed by the Spanish Aerobiology Network, the REA (Galán et al., 2007). In this work, the seasonal evolution of the different taxa, annual pollen index and features of the main pollen season (length and start, end and peak days) are studied and the results obtained in 2013 and 2014 are compared to the average values of the previous years in order to detect differences related to climate change. The annual mean temperature have been rising in 2013 and 2014 (19.1 and 19.9ºC) comparing to the average of the last 20 years (18.7ºC). The annual total rainfall have been declining in 2013 and 2014 (354.7 and 373.1 mm) comparing to the average of the last 20 years (546.2 mm). The relative humidity declined in 2014 (60.6%) compared to last 20 years (66.6%). Among the significant trends that we have observed are: increase in the annual pollen index of Quercus and Olea, decrease in the annual pollen index of Chenopodiaceae, Plantago and Cyperaceae, delay in the end and increase in the length of the main pollen season of Quercus, delay and reduction in the length of the main pollen season of Gramineae pollen.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

    Distribution of sex forms in the phanerogamic flora

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    In the plant kingdom, particularly in the phanerogamic flora, hermaphroditism is by far the most common, yet the number of other sex forms is not negligible. This study was undertaken with the view of ascertaining the relative proportions in which such sex forms occur. For this purpose Engler and Prantls "Natürliche Pflanzenfamilien" with all the Nachträge (which are complete up to 1912) have been used. The lists that follow are the results of this examination

    A phylogeny of Setaria (Poaceae, Panicoideae, Paniceae) and related genera based on the chloroplast gene ndhF

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    The genus Setaria is the largest genus in the so-called bristle clade, a monophyletic group of panicoid grasses distinguished by the presence of sterile branches, or bristles, in their inflorescences. The clade includes both foxtail millet and pearl millet, the latter an important cereal crop in dry parts of the world. Other members of the clade are weeds that are widespread agricultural pests. Previous molecular phylogenetic studies have suggested that Setaria might not be monophyletic but did not have a large enough sample of species to test this rigorously. In addition, taxonomic studies have suggested a close relationship between Setaria and Paspalidium, with some authors combining them into a single genus, but molecular studies included too few Paspalidium accessions for a meaningful conclusion. Accordingly, we have produced 77 new sequences of the chloroplast gene ndhF for 52 species not in previous analyses. These were added to available sequences for 35 species in 10 genera of the bristle clade and four outgroup taxa. We find that Setaria species fall into several moderately to strongly supported clades that correlate with geography but not with the existing subgeneric classification. Relationships among these clades and among other genera within the bristle clade are unclear. Constraint experiments using the approximately unbiased test reject the monophyly of Pennisetum, Setaria, and Setaria plus Paspalidium, as well as several other groupings, although the test may be overly sensitive and prone to Type I error. The more conservative Shimodaira-Hasegawa test fails to reject monophyly of any of the tested clades.Fil: Kellogg, Elizabeth Anne. University of Missouri; Estados UnidosFil: Aliscioni, Sandra Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Botánica Agrícola; ArgentinaFil: Morrone, Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Pensiero, Jose Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Zuloaga, Fernando Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentin

    Iron Age to Medieval entomogamous vegetation and Rhinolophus hipposideros roost in south-eastern Wales (UK)

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    Karst cave systems are well developed in Wales (UK) and, in some instances, constitute important bat roosts. Ogof Draenen, near Blaenavon in south-east Wales, is the most recent major cave discovery (1994) with already > 70 km of passages explored spanning a vertical range of 148 m. With the exception of one small chamber (Siambre Ddu) located directly above the main Ogof Draenen system, very few bats have been noticed inside. Extensive accumulations of guano, attributable to Rhinolophus hipposideros, are however found in parts of the Ogof Draenen system. In places covering many square meters and sometimes building heaps > 0.5 m thick, these represent volumes not yet found in any other cave system in the British Isles. Although the date of the abandonment of the main Ogof Draenen system as a bat roost remains unknown, six radiocarbon dates on guano from Ogof Draenen place the occupation in the Iron Age to Medieval period at least. Palynological analysis was undertaken on ten samples distributed through the cave. Comparisons were made with a moss polster and a lake mud sample from the area to provide a first approximation of the regional modern pollen rain and with two modern guano samples, one from Siambre Ddu and one from Agen Allwedd cave (5 km to the north-west) to provide a temporal comparison with the fossil guano. Agen Allwedd cave currently is one of the largest active roosts for Lesser Horseshoe bats in Britain and lies close to the present northern limit of this endangered species in Europe. The main results are that the cave appears to have been used both as a summer and a winter roost; most of the Ogof Draenen guano is formed within c.1600 14C years and, if the largest heap is continuous, it has accumulated within 750 14C years, i. e. 0.16 mm.year-1; the fossil guano samples reflect a relatively closed oak forest with more abundant ivy (Hedera) and holly (Ilex) than at present; insect-pollinated plants such as Ilex, Acer, Hedera and Impatiens glandulifera are over–represented in the guano samples; in addition to the usual causes of bat roost decline (pesticides, pollution), in the case of Ogof Draenen, we may add entrance blocked by rock collapse and decline of the local forest cover as well as change in its composition
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