1,624 research outputs found

    Review of \u3cem\u3eThe Wild Oat Inflorescence and Seed: Anatomy, Development and Morphology\u3c/em\u3e, M. V. S. Raju

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    This slim volume describes a detailed study of the reproductive parts of Avena fatua, the wild oat plant-a common weed in the northern plains and the probable ancestor of the cultivated oat. The book integrates the author\u27s own work with information from available literature and includes lengthy technical descriptions of the structure and the growth of the inflorescence, the floret, the ovule, the pollen grain, the embryo, the seed, and the young seedling. Throughout the work, the author relates the wild oat\u27s structure and development to other grasses, other monocotyledons, and other seed plants, offering evolutionary interpretations of many of the features observed. He places particular emphasis on the relationship of structure to the onset and breaking of seed dormancy

    Historical Notes on Collections and Taxonomy of Penstemon Haydenii S. Wats. (Blowout Penstemon), Nebraska\u27s Only Endemic Plant Species

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    Penstemon haydenii was originally described in 1891 by Sereno Watson and was named for its first collector, the geologist and explorer Ferdinand V. Hayden, who probably collected it in the late summer of 1857 in the Sand Hills of Loup Fork, Nebraska. The Hayden specimen which Watson saw in the Gray Herbarium at Harvard University had evidently been labeled with an incorrect location. Watson did not base his description on that early specimen but upon a more complete specimen, also in the Gray Herbarium, taken by Herbert J. Webber in Thomas County in 1891; so the Webber specimen, not the earlier Hayden collection, was designated by Francis W Pennell as the type specimen. Between the original Hayden collection and 1968, only about eight collectors had taken the plant, and knowledge of it was very limited. I collected it with Robert Kaul and Dennis Brown in 1968, but I was not aware of its extremely limited distribution until about 1974, when work began on checklists for the Great Plains Flora project

    Review of \u3cem\u3eAmerican Wildflower Florilegium\u3c/em\u3e by Jean Andrews

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    This book is a collection of 50 watercolor paintings of American wildflowers ( florilegium means, literally, a gathering of flowers ). Accompanying each full-page painting is a summary of general information about the plant, including notes about its botanical classification, the etymology of its name, life history, distribution, description, flowering period, pollination, and propagation

    The Effects of Fish Trap Mesh Size on Reef Fish Catch off Southeastern Florida

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    Catch and mesh selectivity of wire-meshed fish traps were tested for eleven different mesh sizes ranging from 13 X 13 mm (0.5 x 0.5") to 76 x 152 mm (3 X 6"). A total of 1,810 fish (757 kg) representing 85 species and 28 families were captured during 330 trap hauls off southeastern Florida from December 1986 to July 1988. Mesh size significantly affected catches. The 1.5" hexagonal mesh caught the most fish by number, weight, and value. Catches tended to decline as meshes got smaller or larger. Individual fish size increased with larger meshes. Laboratory mesh retention experiments showed relationships between mesh shape and size and individual retention for snapper (Lutjanidae), grouper (Serranidae), jack (Carangidae), porgy (Sparidae), and surgeonfish (Acanthuridae). These relationships may be used to predict the effect of mesh sizes on catch rates. Because mesh size and shape greatly influenced catchability, regulating mesh size may provide a useful basis for managing the commercial trap fishery

    Nebraska Plant Distribution

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    Distribution notes based on recent collections and herbarium work are provided for 46 Nebraska plant taxa, including 43 flowering plants, two ferns, and one liverwort. The list includes several plants that are new to the State and provides range extensions within the State for many others. Several previously published distribution records believed to be erroneous are also discussed

    Per Axel Rydbergā€™s Botanical Collecting Trips to Western Nebraska in 1890 and 1891

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    In the summer of 1891, Per Axel Rydberg and his assistant, Julius Hjalmar Flodman, collected plants in western Nebraska for the United States Department of Agriculture. They collected many first-records for Nebraska as well as some that became type specimens of Rydbergā€™s and other botanistsā€™ names. In the following autumn and winter, Rydberg made a detailed, typewritten, carbon copied 35-page Report and 37-page List of specimens from that trip; one carbon copy is in the Bessey Herbarium (NEB) at the University of Nebraskaā€“Lincoln. It is these documents that we present here, extensively annotated with our geographic clarifications, original and updated nomenclature, and citations of specimens in NEB and elsewhere.https://digitalcommons.unl.edu/zeabook/1039/thumbnail.jp

    Nebraska Plant Distribution

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    Distribution notes based on recent collections and herbarium work are provided for 46 Nebraska plant taxa, including 43 flowering plants, two ferns, and one liverwort. The list includes several plants that are new to the State and provides range extensions within the State for many others. Several previously- published distribution records believed to be erroneous are also discussed

    INITIAL CHANGES IN SPECIES COVER FOLLOWING SAVANNA RESTORATION TREATMENTS IN WESTERN IOWA

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    Study areas in the Iowa Loess Hills were used to evaluate short-term responses of understory species to three treatment methods designed to facilitate restoration of Quercus macrocarpa savanna. Treatments included burning alone, burning with thinning, and burning with clear-cutting. Plant abundance and diversity were compared before treatment and one year after treatment. Ninety-nine plant species were identified during the study, of which 40 were new following treatment, although most of these were forest associates. Increases in diversity of understory species were observed after treatment, particularly in plots with combined burning and thinning. The forb group was most consistent in response to treatment, increasing in cover an average of9% in burn-only plots to 33% in burn-clear plots. Carex spp. and Eupatorium rugosum were the species most consistently responsive to treatments, but responses varied widely among other species. Density of canopy tree species generally did not decline with burning, indicating fire alone is ineffective in short-term removal of established trees. Although short term, our results suggest that a combination of prescribed burning and thinning of canopy trees is most likely to provide environmental conditions suitable for increasing the amount and diversity of herbaceous species comparable to a savanna ecosystem, while also increasing fine-fuel loads that will facilitate future prescribed burning

    Human abasic endonuclease action on multilesion abasic clusters: implications for radiation-induced biological damage

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    Clustered damagesā€”two or more closely opposed abasic sites, oxidized bases or strand breaksā€”are induced in DNA by ionizing radiation and by some radiomimetic drugs. They are potentially mutagenic or lethal. High complexity, multilesion clusters (three or more lesions) are hypothesized as repair-resistant and responsible for the greater biological damage induced by high linear energy transfer radiation (e.g. charged particles) than by low linear energy transfer X- or Ī³-rays. We tested this hypothesis by assessing human abasic endonuclease Ape1 activity on two- and multiple-lesion abasic clusters. We constructed cluster-containing oligonucleotides using a central variable cassette with abasic site(s) at specific locations, and 5ā€² and 3ā€² terminal segments tagged with visually distinctive fluorophores. The results indicate that in two- or multiple-lesion clusters, the spatial arrangement of uni-sided positive [in which the opposing strand lesion(s) is 3ā€² to the base opposite the reference lesion)] or negative polarity [opposing strand lesion(s) 5ā€² to the base opposite the reference lesion] abasic clusters is key in determining Ape1 cleavage efficiency. However, no bipolar clusters (minimally three-lesions) were good Ape1 substrates. The data suggest an underlying molecular mechanism for the higher levels of biological damage associated with agents producing complex clusters: the induction of highly repair-resistant bipolar clusters

    New and Corrected Floristic Records for Nebraska

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    Nineteen species (including eight Eurasian ones) are newly recorded for Nebraska: Alopecurus arundinaceus, Amaranthus californicus, Asclepias asperula, A purpurascens, Cardamine {lexuosa*, Centaurea diffusa, Dipsacus laciniatus, Eriochloa villosa, Euclidium syriacum, Gentiana alba, Geranium viscosissimum, Geum vernum, Goodyera oblongifolia, Haplopappus multicaulis, Heterotheca latifolia, Lathyrus tuberosus, Polygonum douglasii, Scirpus saximontanus, Veronica biloba. Twenty-one others are shown to be more widespread in Nebraska than previously known, one has a more restricted range than previously reported, two (Scirpus smithii, S. torreyi) are deleted from the flora based upon corrected identifications, and the status of some rarely-collected species is updated. Thirty-two additions, two deletions, and two corrections to the recentlypublished flora of Seward County are also presented along with thirteen additions to the flora of Keith County
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