3,597 results on '"*BOTANY"'
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2. The Planters of the English Landscape Garden: Botany, Trees, and the Georgics
- Author
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Douglas D. C. Chambers and Ray Desmond
- Subjects
Painting ,Natural kind ,Ecology ,media_common.quotation_subject ,Art history ,Plant Science ,Art ,Ecology, Evolution, Behavior and Systematics ,Natural (archaeology) ,media_common - Abstract
1 The Patriots of Horticulture: An Introduction 2 The Translation of Antiquity: Pliny and Virgil 3 A Grove of Venerable Oaks: John Evelyn and his Contemporaries 4 Things of a Natural Kind: Shaftesbury and the Concept of Nature 5: Rural and Extensive Landscape: Switzer and Ingentia Rura 6 Evergreens and American Plants: The Earl of Islay at Whitton and The Duke of Richmond at Goodwood 7 Painting with Living Pencils: Lord Petre 8 The Practical Part of Gardening: Botanists, Gardeners and Designers 9 Gardeners: Forest Trees for Use and Ornament 10 Nature's Still Improv'd But Never Lost: Philip Southcote and Woburn Farm 11 Prospects and the Natural Beauties of Places: Joseph Spence 12 Smoothing or Brushing the Robe of Nature: William Shenstone and The Leasowes 13 None but Real Professors: A Conclusion. more...
- Published
- 1994
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3. Serpentine Botany
- Author
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B. A. Roberts, J. Proctor, and Peter A. Furley
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Geography ,Ecology ,Ecology (disciplines) ,Ecology, Evolution, Behavior and Systematics - Published
- 1993
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4. Taxonomy and Ecology. Proceedings of an International Symposium Held at the Department of Botany, University of Reading
- Author
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Vernon H. Heywood and Philip W. Rundel
- Subjects
Ecology ,Botany ,Taxonomy (biology) ,Plant Science ,Sociology ,Ecology, Evolution, Behavior and Systematics - Abstract
Taxonomy and ecology; proceedings of an international symposium held at the Dept. of Botany, University of Reading , Taxonomy and ecology; proceedings of an international symposium held at the Dept. of Botany, Univers... , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی more...
- Published
- 1974
- Full Text
- View/download PDF
5. Economic Botany: Plants in Our World
- Author
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Ghillean T. Prance, Beryl B. Simpson, and Molly Conner-Ogorzaly
- Subjects
Plant ecology ,Economic botany ,Geography ,Ecology ,Genetics ,Mineralogy ,Plant physiology ,Plant Science ,Ecology, Evolution, Behavior and Systematics - Published
- 1988
- Full Text
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6. Systematic Botany, Plant Utilization and Biosphere Conservation
- Author
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Charles B. Heiser and Inga Hedberg
- Subjects
Ecology ,Genetics ,Systematic Botany ,Biosphere ,Plant Science ,Biology ,Ecology, Evolution, Behavior and Systematics - Published
- 1980
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7. Natural History of the Phlox Family. Volume I. Systematic Botany
- Author
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Verne Grant and J. H. Harper
- Subjects
Natural history ,Ecology ,biology ,Phlox ,Botany ,Systematic Botany ,Plant Science ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Volume (compression) - Published
- 1961
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8. An Introduction to the Botany of Tropical Crops
- Author
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Leslie S. Cobley and C. A. Thorold
- Subjects
Economic botany ,Ecology ,Tropical agriculture ,Agroforestry ,Plant Science ,Horticultural botany ,Biology ,Ecology, Evolution, Behavior and Systematics - Published
- 1958
- Full Text
- View/download PDF
9. Systematic Botany, Plant Utilisation and Biosphere Conservation
- Author
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Inga Hedberg and G. E. Wickens
- Subjects
Ecology ,Systematic Botany ,Biosphere ,Plant Science ,Biology ,Ecology, Evolution, Behavior and Systematics - Published
- 1980
- Full Text
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10. Observations on the Use of Cluster Analysis in Botany with an Ecological Example
- Author
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A. J. B. Anderson and N. M. Pritchard
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Biological data ,Ecology ,media_common.quotation_subject ,Judgement ,Analogy ,Plant Science ,Biology ,law.invention ,Numerical taxonomy ,Biologist ,Taxon ,law ,Botany ,CLARITY ,Sophistication ,Ecology, Evolution, Behavior and Systematics ,media_common - Abstract
ever-increasing number of accounts of techniques for the handling of very large quantities of biological data. In botanical work this flow starts with the pioneer studies of Williams & Lambert (1959). Against the undoubted refinements of modern techniques it seems prudent to balance their proliferation; increased sophistication of computer methods is not necessarily associated with greater clarity and utility of the resulting classifications. Many workers have pointed out that the ability of computers to sift data in no way relieves the biologist of his responsibility for the choice of criteria or careful judgement of the results. Computer taxonomy and ecology do not really pose the same problems, although they have often been confused (notice the frequent use of the blanket term 'numerical taxonomy'.) In taxonomy the units considered are individual organisms which must be grouped, usually hierarchically. At any level in the hierarchy the possible variations on the theme are very limited; the viability of the individual and the natural boundaries of the taxon establish its limits. Even where, in 'difficult' taxa, the individual groups merge into one another, there always develop eventually more or less clearly marked natural discontinuities which are inevitably picked out whether the techniques used are those of the classical taxonomist, the experimental taxonomist or the computer taxonomist. Within the groups defined by these discontinuities there is little room available for manoeuvering; the morphogenetic processes involved in the development of viable individuals presumably leave little to chance. The commonly drawn analogy to this of ecological community structures has generally appealed to analysts of botanical data; the analogy needs justification. It is doubtful if discontinuities of a similar sort are to be found among plant communities; however closely a plant is integrated with its environment, it seems unlikely that the integration can be as great as that of, say, a particular chromosome configuration, the development pattern of the auditory apparatus or the functioning of a multiple allele sterility system within their individual animals or plants. All of these are, or can give rise to, criteria used in the taxonomy of organisms. The occurrence of such characters in animals or plants is definitive of the organisms concerned, and leaves little room for chance inclusion or omission. The interest in the phytosociological analyses of plant communities lies in the overall facies of the communities, and not in the presence or absence of any particular species. Yet the techniques available depend essentially on such presence or absence data, or at best on some estimate of the abundance of the species more...
- Published
- 1971
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11. Cryptogamic Botany. Volume I, Algae and Fungi
- Author
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W. L. Culberson and Gilbert M. Smith
- Subjects
Volume (thermodynamics) ,Algae ,biology ,Ecology ,Botany ,Plant Science ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics - Published
- 1955
- Full Text
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12. Physics in Botany
- Author
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I. R. Cowan and J. A. Richardson
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Ecology ,Respiration ,Botany ,Plant physiology ,Photosynthesis - Published
- 1964
- Full Text
- View/download PDF
13. The Botany of Mangroves
- Author
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P. B. Tomlinson and F. D. Por
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Geography ,Ecology ,Plant Science ,Mangrove ,Ecology, Evolution, Behavior and Systematics - Published
- 1987
- Full Text
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14. The Botany of Mangroves
- Author
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Daniel F. Austin and P. B. Tomlinson
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Geography ,Ecology ,Plant Science ,Mangrove - Published
- 1987
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- View/download PDF
15. The Botany of Mangroves
- Author
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Alwyn H. Gentry and P. B. Tomlinson
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Ecology ,Plant Science ,Biology ,Mangrove ,Ecology, Evolution, Behavior and Systematics - Published
- 1987
- Full Text
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16. The Botany of Mangroves
- Author
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Peter J. Edwards and P. B. Tomlinson
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Geography ,Ecology ,Plant Science ,Mangrove ,Ecology, Evolution, Behavior and Systematics - Published
- 1987
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17. Fishing Rod Botany; A Review
- Author
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N. W. Simmonds
- Subjects
Ecology ,Fishing ,Plant Science ,Biology ,Ecology, Evolution, Behavior and Systematics - Published
- 1956
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18. Studies in Florida Botany 8. The Genus Habenaria in Florida
- Author
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Alex D. Hawkes
- Subjects
Flora ,Geography ,biology ,Ecology ,Genus ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Habenaria - Abstract
As in the other large generic aggregations in Florida, we find, unfortunately, that the members of Habenaria occurring within the confines of this state are still incoinpletely known, and, in several instances, their exact taxonomic limitations are not understood. This study, therefore, is not to be taken as a monographic treatment of this group in Florida, but rather as a contribution toward our knowledge of these interesting orchids in the lnative flora more...
- Published
- 1950
- Full Text
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19. Botany of the Cambridge Expedition to Edge Island, S.E. Spitsbergen, in 1927: Part II. The Vegetation
- Author
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A. P. G. Michelmore
- Subjects
geography ,geography.geographical_feature_category ,Ecology ,biology ,Cerastium ,Plant Science ,Vegetation ,biology.organism_classification ,Archaeology ,Genus ,Draba ,Archipelago ,Lichen ,Ecology, Evolution, Behavior and Systematics - Abstract
IN the course of the late Mr H. G. Watkins' Cambridge Expedition to Edge Island in 1927 some observations were made on the vegetation. Lists of the species of plants found and of the places visited have been given in the first part of this paper (3). The ecological notes made are here presented and correlated with Summerhayes and Elton's work on the ecology and zonation of the vegetation of Spitsbergen (4, 5). Their papers summarise the work of their predecessors so fully that there is no need to refer again to the earlier writers. It was not found possible to study the Fungi, Lichens or Bryophytes apart from making general notes on their presence or absence. On the flowering plants also the notes were incomplete, because some of the grasses, particularly those of the genus Poa, the hairy forms of Cerastium, the yellow-flowered species of Draba of the D. alpina group and a few other plants were not distinguished properly in the field. The object of the expedition was to explore Edge Island2, which is the south-eastern of the four main islands forming the Spitsbergen archipelago. We landed also at two places on Barents' Island, the island which lies to the north of Edge Island. The geology and topography of the two islands are similar, and the vegetation at these two places was like that of similar spots more...
- Published
- 1934
- Full Text
- View/download PDF
20. Better Grassland Sward: Ecology, Botany, Management
- Author
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Catherine T. M. Herriet, Paul C. Lemon, and Andre Voisin
- Subjects
Geography ,geography.geographical_feature_category ,Ecology ,Ecology (disciplines) ,Animal Science and Zoology ,Grassland - Published
- 1961
- Full Text
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21. Radiation Botany
- Author
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H. M. Bowen
- Subjects
Ecology ,Plant Science ,Ecology, Evolution, Behavior and Systematics - Published
- 1963
- Full Text
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22. The Botany of Ice-Island T-3
- Author
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Nicholas Polunin
- Subjects
Ecology ,Plant Science ,Archaeology ,Ecology, Evolution, Behavior and Systematics ,Geology - Published
- 1958
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23. Arctic Botany
- Author
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N. Y. Sandwith and Nicholas Polunin
- Subjects
Flora ,Geography ,Arctic ,Ecology ,Plant Science ,Circumpolar star ,Ecology, Evolution, Behavior and Systematics - Published
- 1960
- Full Text
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24. Records of the American-Australian Scientific Expedition to Arnhem Land. 3. Botany and Plant Ecology
- Author
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C. P. Mountford, R. L. Specht, and C. G. G. J. van Steenis
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Plant ecology ,Geography ,Ecology ,Plant Science ,Archaeology ,Ecology, Evolution, Behavior and Systematics - Published
- 1960
- Full Text
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25. Economic Botany
- Author
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K. R. Sporne and A. F. Hill
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Ecology ,Plant Science ,Ecology, Evolution, Behavior and Systematics - Published
- 1953
- Full Text
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26. Gray's Manual of Botany, Edition VIII
- Author
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M. L. Fernald and S. M. Walters
- Subjects
Ecology ,media_common.quotation_subject ,Art history ,Plant Science ,Art ,Gray (horse) ,Ecology, Evolution, Behavior and Systematics ,media_common - Published
- 1951
- Full Text
- View/download PDF
27. Physics in Botany
- Author
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J. A. Richardson and A. J. Rutter
- Subjects
Ecology ,Plant Science ,Ecology, Evolution, Behavior and Systematics ,Classics - Published
- 1965
- Full Text
- View/download PDF
28. Australian and New Zealand Botany
- Author
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K. R. Sporne, J. McLuckie, and H. S. McKee
- Subjects
Ecology ,Plant Science ,Ecology, Evolution, Behavior and Systematics - Published
- 1955
- Full Text
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29. Botany of the Canadian Eastern Arctic, Part III, Vegetation and Ecology
- Author
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Nicholas Polunin and Murray F. Buell
- Subjects
Part iii ,Geography ,Arctic ,Ecology ,Ecology (disciplines) ,medicine ,Plant Science ,medicine.symptom ,Vegetation (pathology) - Published
- 1950
- Full Text
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30. Species Concepts: Assumptions, Methods, and Applications
- Author
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Melissa Luckow
- Subjects
Systematics ,Ecology ,media_common.quotation_subject ,Systematic Botany ,Context (language use) ,Plant Science ,Biology ,Terminology ,Monophyly ,Taxon ,Evolutionary biology ,Genetic algorithm ,Genetics ,Phyletic gradualism ,Ecology, Evolution, Behavior and Systematics ,media_common - Abstract
The assumptions, methods, and applications of various species concepts prevalent in systematics are reviewed in order to clarify issues and terminology. Species concepts are classified as mechanistic-species as participants in the process of speciation, or historical-species as the end results of processes. Mechanistic concepts lack universality and testability because they rely on a knowledge of how speciation proceeded in any particular case. Historical species concepts are preferred because they can be consistently applied and provide a context in which processes of speciation can be investigated. Three historical species concepts are compared: the Genealogical Species Concept, the Species As Taxa Concept, and the Phylogenetic Species Concept. The Gene- alogical Species Concept supports the recognition of the smallest monophyletic lineages (those that occur at the boundary between reticulating and hierarchical systems of relationship), whereas under the Species As Taxa Concept, hierarchy is considered to occur below the level of species, and any monophyletic unit may be recognized as a species. The problems presented by applying the term monophyly to reticulating systems are discussed as they apply to each concept, as are several problems specific to the Genealogical Species Concept, such as metaspecies. An alternative to mono- phyletic species concepts is the Phylogenetic Species Concept, in which the smallest diagnosable unit is recognized as a species. Monophyly is not considered demonstrable at the species level because, in contrast to Species As Taxa, an assumption of the Phylogenetic Species Concept is that species are basal taxa, and thus mark the level at which hierarchic relationships begin. Finally, the application of species concepts is reviewed by surveying the literature in Systematic Botany and Systematic Zoology/Biology during the past five years. Papers in Systematic Zoology/Biology were generally more explicit about the species concept and the criteria being used to delimit species than were papers in Systematic Botany. Because it is clear that a number of different concepts are currently in use, and these are often distinguished only vaguely, botanists are encouraged to familiarize themselves with the various concepts, and to state explicitly which concepts and criteria are being employed in recognizing species. more...
- Published
- 1995
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31. Stem Morphology and Anatomy in Amaranthus L. (Amaranthaceae), Taxonomic Significance
- Author
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Mihai Costea and Darleen A. DeMason
- Subjects
Ecology ,biology ,Botany ,Taxonomy (biology) ,Plant Science ,Amaranthaceae ,Anatomy ,Subgenus ,Phyllotaxis ,biology.organism_classification ,Vascular supply ,Ecology, Evolution, Behavior and Systematics ,Trichome - Abstract
COSTEA, MIHAI (Department of Botany, University of Agronomical Sciences, Bucharest, Romania) and DARLEEN DEMASON (Botany and Plant Sciences, University of California, Riverside, CA 92521). Stem morphology and anatomy in Amaranthus L. (Amaranthaceae) taxonomic-significance. J. Torrey Bot. Soc. 128: 254-281. 2001.-The range of variation within the genus Amaranthus L. (Amaranthaceae) is described for a number of stem characters including: morphology, epidermis, primary stem vasculature and mechanism of secondary growth. The results provide new characters (phyllotaxy, complexity of leaf vascular supply and relative amount of secondary growth) that support (1) a new infrageneric classification (subgenus Amaranthus vs subgenus Albersia (Kunth)Gren. & Dodr.), and (2) the separation within the "hybridus" complex of cultivated amaranths (A. caudatus L., A. cruentus L. and A. hypochondriacus L.) from their presumed wild ancestors (A. hybridus L. subsp. quitensis (Kunth) Costea & Carretero, A. hybridus L. subsp. hybridus and A. powellii S. Wats. subsp. powellii respectively). more...
- Published
- 2001
- Full Text
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32. Spatial Variation of Prickle Abundance on Leaves of the Devil's Walking Stick (Aralia spinosa; Araliaceae) during the Trunk-Building Phase
- Author
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Christopher H. Briand and Connie L. Soros
- Subjects
Walking stick ,Leaflet (botany) ,Ecology ,biology ,Epidermis (botany) ,Cuticle ,Plant Science ,Aralia spinosa ,biology.organism_classification ,Frugivore ,Abundance (ecology) ,Botany ,Araliaceae ,Ecology, Evolution, Behavior and Systematics - Abstract
BRIAND, C.H. AND C.L. SOROS (Department of Biological Sciences, Henson School of Science and Technology, Salisbury University, Salisbury MD 21801, USA and Department of Botany, University of Toronto, Toronto, ON, Canada M5S 3B2). Spatial variation of prickle abundance on leaves of the devil's walking stick (Aralia spinosa; Araliaceae) during the trunk-building phase. J. Torrey Bot. Soc. 128: 219-225. 2001 -The bi-tripinnately compound leaves of Aralia spinosa are covered on both their axes and leaflet surfaces with numerous prickles. There was a positive correlation between prickle density on the adaxial and abaxial leaf surfaces, with prickle density highest on the adaxial surface. Although prickle density declined with both ramet height and leaf position along the length of the stem, only about 8% of this variation could be explained by either of these variables. Leaf prickle density varied considerably among ramets within a site, but varied little among sites. Prickles were always associated with veins and the prickles represent outgrowths of the epidermis and underlying parenchyma cells. No vascular connection exists, however, between veins and adjacent prickles. The epidermis of prickles was found to be highly lignified and covered with a thick cuticle. Leaf prickles may (1) act to deter insects from landing and/or crawling on the leaflets, especially the adaxial surface; (2) deter large herbivores from feeding; (3) protect fruit from frugivores other than seed dispersers; or (4) protect stems from physical damage by larger animals. more...
- Published
- 2001
- Full Text
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33. Crown Loss and Subsequent Branch Sprouting of Forest Trees in Response to a Major Ice Storm
- Author
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Neil Charbonneau, Lenore Fahrig, Angela G. Brommit, and Thomas A. Contreras
- Subjects
Canopy ,Prunus serotina ,Tree canopy ,Ecology ,Crown (botany) ,Storm ,Plant Science ,Biology ,biology.organism_classification ,Horticulture ,Disturbance (ecology) ,Botany ,Dominance (ecology) ,Ecology, Evolution, Behavior and Systematics ,Sprouting - Abstract
BROMMIT, A., N. CHARBONNEAU, T. A. CONTRERAS and L. FAHRIG (Department of Biology, Carleton University, Ottawa, Ontario, Canada, K1S 5B6). Crown loss and subsequent branch sprouting of forest trees in response to a major ice storm. J. Torrey Bot. Soc. 131: 169-176. 2004.-In January of 1998, a severe ice storm hit much of eastern Ontario, western Quebec, and the northeastern United States. The objective of this study was to determine whether this disturbance could result in short-term changes in canopy dominance by different tree species. We measured canopy loss in 1998 of 2,919 trees in 164 forest plots distributed across the Ottawa, Ontario region. In 2000, we measured branch sprouting in the same trees. We found a positive cross-species relationship between the proportion of stems damaged by the ice storm and the proportion of stems showing branch sprouting in response to damage (r = 0.498, P = 0.01). Prunus serotina and Acer rubrum showed exceptionally high sprouting-to-damage ratios, whereas Fagus grandifolia and Populus tremuloides showed exceptionally low ratios. Mean percent crown loss and mean number of branch sprouts on damaged stems were also correlated across species (r = 0.404, P = 0.04). Prunus serotina and Quercus macrocarpa showed exceptionally high mean number of branch sprouts and Carpinus caroliniana showed exceptionally low mean number of branch sprouts compared to other species. No conifer species showed any branch sprouting. We predict that due to these different sprouting-to-damage ratios, species such as Prunus serotina, Acer rubrum, and possibly Quercus macrocarpa, may become better represented in the forest canopy while Fagus grandifolia, Populus tremuloides, and conifer species may become less well represented in the canopy in the short-term. These changes in canopy dominance may be prolonged if ice storms become more common due to climate change. more...
- Published
- 2004
- Full Text
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34. Biological Soil Crust and Vascular Plant Communities in a Sand Savanna of Northwestern Ohio
- Author
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Roberta M. Veluci, Jeffrey R. Johansen, Janet Traub, Susan Will-Wolf, James Toppin, Kelly Saiya-Cork, Deborah A. Neher, Timothy L. Walters, Thomas R. Weicht, and Elliot Tramer
- Subjects
Vascular plant ,Rhizosphere ,Ecology ,biology ,Cladonia ,Agroforestry ,Soil biology ,Biological soil crust ,Plant community ,Plant Science ,biology.organism_classification ,Common species ,Botany ,Lichen ,Ecology, Evolution, Behavior and Systematics - Abstract
NEHER, D. A., T. L. WALTERS, E. TRAMER, T. R. WEICHT, R. M. VELUCI, K. SAIYA-CORK (Department of Earth, Ecological and Environmental Sciences, University of Toledo, Toledo, OH 43606) S. WILL-WOLF (Department of Botany, University of Wisconsin, 430 Lincoln Drive, Madison, WI 53706-1381), J. TOPPIN, J. TRAUB (Whitehouse, Ohio 43571-9803) AND JOHANSEN, J. R (Department of Biology, John Carroll University, University Heights, Ohio 44118). Biological soil crust and plant communities in a sand savanna of northwestern Ohio. J. Torrey Bot. Soc. 130:244-252. 2003. A survey of biological crust components (bryophytes, lichens, chlorophyta, bacteria), soil fauna (nematodes, collembolans, mites) and vascular plants was conducted in a dry sand savanna in northwestern Ohio between 1995 and 2001. In soil, six free-living chlorophytes and seven cyanobacteria taxa were identified. Chlorophyta were more abundant than cyanobacteria with Desmococcus olivaeus and Stichococcus bacillaris being the most common species. For bryophytes, the most common species were Polytrichum piliferum and Ceratodon purpureus, and for lichens, Cladonia species. Notably, we found lichen species in the crusts have chlorophytes not cyanobacteria, as their photobionts. Twenty-seven families and 29 genera of nematodes, and four collembolan species were identified in crust and rhizosphere communities. Autotrophic denitrifying bacteria were not detectable with the method employed. The biological crust occurred among a vascular plant community with Robinia pseudoacacia, Rubus flagellaris, Bromus inermis, and Vicia villosa as the most abundant tree, shrub, graminoid, and non-grass herbaceous plants, respectively. To our knowledge, this is the first report of microbial crust community composition in xeric patches of northwestern Ohio. Moreover, our report includes a report of soil nematode or collembolan communities associated with soil biological crust communities. more...
- Published
- 2003
- Full Text
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35. A Digital Photographic Technique for Assessing Forage Utilization
- Author
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Ed L. Fredrickson, Dean M. Anderson, Richard E. Estell, P.W. Hyder, M. D. Remmenga, and R.D. Pieper
- Subjects
Biomass (ecology) ,Ecology ,Statistics ,Botany ,Range (statistics) ,Animal Science and Zoology ,Regression analysis ,Forage ,Sample collection ,Repeatability ,Simple linear regression ,Image analysis ,Mathematics - Abstract
Changes in forage utilization have been difficult to measure non-destructively without some level of subjectivity. This subjec tivity, combined with a lack of reproducibility of visual estimates, has made forage utilization measurement techniques a topic of considerable discussion. The objective of this study was to devel op and test the accuracy and repeatability of an objective, com puter-based technique for measuring changes in plant biomass. Digital photographs of target plants acquired before and after partial defoliation were analyzed using readily available image analysis software. Resulting data were used to develop a simple linear random coefficient model (RC) for estimation of plant bio mass removed based on the area of the plant in the photo. Sample collection took approximately 20 minutes/plant for alfal fa (Medicago sativa L.). Analysis of images took another 60 to 90 minutes. Regression analysis gave an R 2 of 0.969 for predicted vs. observed plant weights. Testing this model using 10 alfalfa plants yielded weight estimates of defoliated plants accurate to within +/‐ 8.5%. The advantage of the RC model is its ability to use easily obtained coefficients from simple linear regression models developed from each plant in a way that accounts for the lack of independence between samples within an individual plant. The technique described here offers an objective and accurate method for measuring changes in plant biomass with possible applications in ecology, botany, and range science. In particular, application of this technique for estimating forage utilization may improve accuracy of estimates and, thereby, improve range management practices. more...
- Published
- 2003
- Full Text
- View/download PDF
36. Changes in Shrub Fecundity in Fourwing Saltbush Browsed by Cattle
- Author
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Andres F. Cibils, Richard H. Hart, and David M. Swift
- Subjects
geography ,geography.geographical_feature_category ,Ecology ,biology ,ved/biology ,Steppe ,Dioecy ,ved/biology.organism_classification_rank.species ,Crown (botany) ,food and beverages ,Fecundity ,biology.organism_classification ,Shrub ,Pasture ,Agronomy ,Botany ,Animal Science and Zoology ,Atriplex canescens ,Sex ratio - Abstract
Shrub fecundity is critical to long term persistence of fourwing saltbush (Atriplex canescens (Pursh) Nutt.) populations at our research site on the shortgrass steppe in Colorado. We conducted a 2-year experiment to test hypotheses concerning the impact of cattle-browsing on fecundity-related variables in fourwing saltbush. Protection from cattle browsing was significantly associated with floral phenotype shifts toward femaleness, occurring mostly in monecious shrubs (1% and 13% of grazed and protected shrubs, respectively). Sex shifts observed at the individual shrub level did not translate into detectable alterations of sex ratios at the pasture level. Shrubs exhibiting no flowers were considerably more abundant in browsed pastures (26.5%) than in exclosures (1.5%). Nonflowering occurred as frequently in female (3.6%) as it did in male (1.8%) phenotypes. Percent utricle fill was not related to previous year's cattle browsing regime (39% and 44% in protected and grazed shrubs, respectively) but rather to crown volume of the fruiting female and to the gender of and distance to the nearest neighboring shrub. The influence of cattle-browsing on reproductive output of fourwing saltbush occurred mainly through its inhibition of flowering. DOI:10.2458/azu_jrm_v56i1_cibils more...
- Published
- 2003
- Full Text
- View/download PDF
37. Intermediate Wheatgrass and Russian Wildrye Responses to Defoliation and Moisture
- Author
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J.R. Hendrickson and J.D. Berdahl
- Subjects
Field capacity ,Ecology ,Perennial plant ,Agronomy ,Grazing ,Crown (botany) ,Thinopyrum intermedium ,Animal Science and Zoology ,Tiller (botany) ,Forage ,Psathyrostachys juncea ,Biology ,biology.organism_classification - Abstract
Perennial forage grasses in the Northern Great Plains are often grazed under water-limiting conditions. The effects of defoliation and soil moisture dynamics on herbage yield, tiller recruitment and number of crown positions for 2 perennial forage grasses were evaluated in a greenhouse experiment at Mandan, N.D. Intermediate wheatgrass (Thinopyrum intermedium (Host) Barkw. &D.R. Dewey] and Russian wildrye (Psathyrostachys juncea (Fisch.) Nevski] were grown at 75, 50, or 40% of field capacity and left as undefoliated controls or defoliated at 10-day intervals to an 8- or 4-cm stubble height. Cumulative herbage yield exhibited defoliation level by soil moisture (P = 0.0001) and species by defoliation (P = 0.007) interactions. Yield decreased with increasing defoliation intensity at 75 and 50% of field capacity, but at 40% of field capacity only the most intense defoliation level was significantly affected. Russian wildrye produced more herbage (1.97 g plant(-1)) than intermediate wheatgrass (1.36 g plant(-1)) under severe defoliation level. Increased defoliation intensity (P = 0.0001) but not water availability (P > 0.05) decreased tiller numbers. Pooled across all treatments, Russian wildrye produced 10 tillers per plant and intermediate wheatgrass produced 7 (P = 0.0001). This may partially explain Russian wildrye's greater grazing tolerance. The number of crown positions (potential axillary bud sites in the bottom 20mm of the plant) was similar between species suggesting that increased tiller numbers in Russian wildrye occurred because its axillary buds were more readily activated than intermediate wheatgrass. Moderate and severe defoliation reduced the number of crown positions on parent seedlings to only 62 and 50% of the number of crown positions of control seedlings, respectively. Water stress decreased (P = 0.004) number of crown positions at 40% of field capacity but only when crown positions of both parent and daughter tillers were pooled. In this experiment, defoliation had a greater effect than water stress. Moisture level mainly affected tiller size not numbers. The interaction between defoliation and water stress should be examined in field studies to foster improved management of these 2 grasses. DOI:10.2458/azu_jrm_v55i1_hendrickson more...
- Published
- 2002
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38. How Experimental Defoliation and Leaf Height Affect Growth and Reproduction in Trillium grandiflorum
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Donald M. Waller and Thomas P. Rooney
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Biomass (ecology) ,Herbivore ,Ecology ,media_common.quotation_subject ,Plant Science ,Biology ,Herbaceous plant ,biology.organism_classification ,Trillium ,Horticulture ,Relative growth rate ,Botany ,Reproduction ,Ecology, Evolution, Behavior and Systematics ,media_common - Abstract
ROONEY, THOMAS P. AND DONALD M. WALLER (Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison WI 53706). How experimental defoliation and leaf height affect growth and reproduction in Trillium grandiflorum. J. Torrey Bot. Soc. 128: 393-399. 2001.-Both defoliation and higher leaf placement can reduce growth in herbaceous plants. We examined variation in relative growth rate (RGR) and reproduction in response to defoliation and leaf height in Trillium grandiflorum at 4 sites in northern Wisconsin, USA. Plant biomass and the probability of flowering increased with increased leaf height. Analyses of covariance revealed that experimental defoliation and leaf height separately and independently reduced individual RGR, and accounted for about 42% of the total variance in RGR. Defoliation in 1998 had no effect on flowering in 1999, but leaf height in 1998 was positively associated with the likelihood of flowering in 1999. RGR and plant responses to defoliation varied among sites. We conclude that defoliation and leaf height reduce RGR over short time scales. more...
- Published
- 2001
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39. Amaranthus rudis and A. tuberculatus, One Species or Two?
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Donald B. Pratt and Lynn G. Clark
- Subjects
Gynoecium ,Ecology ,biology ,Plant morphology ,Botany ,Amaranthus tuberculatus ,Taxonomy (biology) ,Geographic variation ,Plant Science ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Molecular taxonomy ,Hybrid - Abstract
PRATT, D.B. AND L.G. CLARK (Department of Botany, Iowa State University, Ames, IA 50011-1020). Amaranthus rudis and A. tuberculatus-one species or two? J. Torrey Bot. Soc. 128: 282-296. 2001.-Waterhemps traditionally have been divided into two species, Amaranthus rudis and A. tuberculatus, based on morphology, but the distinctions break down for specimens collected from a major portion of the total waterhemp geographic range. Two hypotheses of waterhemp species circumscriptions were explored using morphological and isozyme data sets. The first hypothesis holds that there are two waterhemp species as traditionally circumscribed, intermediate morphological materials being hybrids. The second hypothesis holds that there is a single, polymorphic species of waterhemp. Principal components analysis of pistillate morphological, staminate morphological, and isozyme data sets all show a single waterhemp continuum exhibiting geographic variation. A single waterhemp species, A. tuberculatus, is proposed. more...
- Published
- 2001
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40. Predictive Equations for Biomass and Fuel Characteristics of Argentine Shrubs
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Lyn C. Branch, Diego Villarreal, Kenneth L. Clark, and Jose Luis Hierro
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Biomass (ecology) ,geography ,geography.geographical_feature_category ,Ecology ,biology ,ved/biology ,Crown (botany) ,ved/biology.organism_classification_rank.species ,biology.organism_classification ,Bulk density ,Shrub ,Shrubland ,Agronomy ,Chuquiraga ,Botany ,Environmental science ,Animal Science and Zoology ,Larrea ,Woody plant - Abstract
Predictive equations for estimating shrub biomass in semi-arid scrub ecosystems are essential for evaluating shrub encroachment, conducting ecosystem-level studies of net primary productivity (NPP) and nutrient cycling, and examining effects of different fire regimes. In this study, we developed predictive equations to estimate total aboveground biomass and biomass of foliage and stems of the 8 most common shrubs in the semi-arid scrub (Monte) of central Argentina. We also examined the relationship between shrub size and proportions of these components for the dominant species, Larrea divaricata Cavanilles (creosotebush), and determined fuel characteristics (dead-to-live ratio, bulk density) of the 8 shrub species. Regression analyses were used to examine the relationships between aboveground biomass and 5 field measurements (diameter of the longest stem, shrub height, maximum crown width, crown width at right angles to maximum crown width, and crown volume). A natural log-log model based on a single variable best described this relationship in most cases. The easiest field measurement for 6 of the 8 species was diameter of the longest stem, and this measure was often the best predictor of shrub biomass. As L. divaricata increased in size, the proportional biomass of large stems increased, and bio mass of foliage and small stems decreased. This pattern suggests pro ductivity may decrease with shrub age. The mass of dead material was low in most shrub species. Bulk densities were comparable to those of shrubs in other semi-arid ecosystems. Equations developed here will allow rapid and accurate estimation of shrub biomass in the Monte of Argentina. more...
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- 2000
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41. The Illustrated Flora of Illinois. Sedges: Carex
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P. E. Rothrock and Robert H. Mohlenbrock
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Carex ,Flora ,Ecology ,Botany ,Genetics ,Plant Science ,Biology ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics - Published
- 2000
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42. Variation in Tree Fern Stipe Length with Canopy Height: Tracking Preferred Habitat through Morphological Change
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Patricia Sanchez Baracaldo and Nan Crystal Arens
- Subjects
Canopy ,Frond ,Tree canopy ,biology ,Ecology ,Plant Science ,Understory ,biology.organism_classification ,Stipe (botany) ,Plant morphology ,Botany ,Fern ,Allometry ,Ecology, Evolution, Behavior and Systematics - Abstract
Cyathea caracasana is a common open-habitat tree fern in the Andes of Colombia. In full sun, stem growth rates are high (up to 2 cm/month) and individuals regularly produce spores. However, even the fastest growing ferns are overtopped by woody angiosperms after 10 to 15 years of natural forest regeneration. As individuals are overtopped, C. caracasana produces nearly vertical fronds with long stipes (commonly over 3 m) apparently to place the photosynthetic surface into the canopy. We compared stipe length and blade length and width among individuals growing in open sites and in the understories of two regenerating forests: one with a canopy of 20-25 m, and one with a canopy of 5-8 m. Stipes and blades were shortest in open habitat and longest in the low-canopy forest. Ferns in the high-canopy forest had intermediate measurements. Despite the change in frond length, the number of primary pinnae per-frond did not differ among the habitats sampled. This suggests that elongation cues are received late in the development of the frond. This conclusion is supported by a positive relationship between stipe length and the distance of the fern meristem below the canopy. Because both understory populations show stipe elongation relative to open-hapitat ferns, the cue to elongate is likely a low red/far-red wavelength ratio of the light received by the apical meristem. Extraordinary elongation is probably made possible by extra carbon resources available to low-canopy plants, which still have leaves in full sun. This sense and response mechanism allows individual plants to produce elongated fronds as their apical meristems are overtopped. Functionally, the long-stiped plants remain in full sun even after they are overtopped, thus they "track" their preferred, open habitat. Plant populations respond to environmental variation in several ways. When the environment fluctuates infrequently relative to the life span of individuals, adaptive segregation may produce differential response to environmental cues among separate populations. Consider variation in light environment. Sunadapted populations of Impatiens capensis L. showed enhanced growth in response to changes in the ratio of red (600-700 nm) to far-red (700-850 nm) light relative to shade-adapted populations (Dudley and Schmitt, 1995). Similar sun/shade segregation in growth response to red/far-red (R/FR) has been observed in many angiosperm species in open (as compared to understory) communities (Morgan and Smith, 1979). In contrast, when the environment varies frequently relative to the life span of individuals, adaptive segregation cannot occur and individuals must rely on morphological and physiological flexibility (plasticity) (Thompson, 1991; Sultan, 1993; Ackerly and Bazzaz, 1995; Arens, 1997). In such cases, plants may change form or physiology to suit new conditions, for example switching from sun-leaf to shade-leaf anatomy (Arens, 1997). Alternatively, individuals "track" or follow their preferred habitat as it moves. Conventionally, habitat-tracking in plants has been applied to intergenerational migration (Davis et al., 1986; Webb, 1987; Davis and SaThis content downloaded from 157.55.39.128 on Mon, 18 Jul 2016 03:58:47 UTC All use subject to http://about.jstor.org/terms AMERICAN FERN JOURNAL: VOLUME 90 NUMBER 1 (2000) more...
- Published
- 2000
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43. Species and Evolution in Clonal Organisms-Introduction
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Ann F. Budd and Brent D. Mishler
- Subjects
Cohesion (linguistics) ,Ecology ,Genetic algorithm ,Genetics ,Systematic Botany ,Plant Science ,Biological evolution ,Biology ,Ecology, Evolution, Behavior and Systematics ,Epistemology - Abstract
Six papers presented in the symposium follow in this issue, bolstered by the addition of material derived from peer reviews plus discussion at the symposium itself. With four of the six papers dealing with plants, we feel that Systematic Botany is an appropriate outlet for this topic of general biological interest. The goal of this introduction is to set the stage by introducing three major issues that are common to all papers. We will first briefly review competing species concepts, and the expected patterns of species distinctness. We will then consider mechanisms possibly responsible for causing integration and cohesion of species. Finally, we will discuss what «speciation» might be under these different concepts of species and under various possible integrating mechanisms more...
- Published
- 1990
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44. A New Lightweight-Wooded Species of Anaxagorea (Annonaceae) from Flooded Black-Water Shrublands in Southern Venezuela
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Regis B. Miller, Paul E. Berry, and Alex C. Wiedenhoeft
- Subjects
Blackwater ,geography ,geography.geographical_feature_category ,biology ,Ecology ,Plant Science ,Structural basin ,biology.organism_classification ,Shrubland ,Habitat ,Annonaceae ,Botany ,Genetics ,Ecology, Evolution, Behavior and Systematics ,Anaxagorea - Abstract
Anaxagorea inundata P. E. Berry & R. B. Miller is a distinctive new species from the black- water Rio Atabapo basin in southern Venezuela. It is adapted to its strongly flooded habitat by producing very lightweight wood (specific gravity more...
- Published
- 1999
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45. Molecular Systematics of Australian Gossypium Section Grandicalyx (Malvaceae)
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Curt L. Brubaker, Lyn A. Craven, Jonathan F. Wendel, Tosak Seelanan, and James McD. Stewart
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Mutualism (biology) ,Ecology ,Botany ,Molecular phylogenetics ,Genetics ,Plant Science ,Biology ,Gossypium ,biology.organism_classification ,Monsoon ,Ecology, Evolution, Behavior and Systematics ,Malvaceae ,Herbaceous perennial - Abstract
Australian Gossypium consists of 17 species classified into three sections. The largest and most poorly understood is the group of 12 species in sect. Grandicalyx that occur in the Kimberley and Cobourg regions of NW Australia. These areas are characterized by annual monsoon rains and dry-season fires. Species in sect. Grandicalyx exhibit a suite of morphological and ecological features that are otherwise unknown in the genus and that apparently evolved in response to seasonal fires and ant mutualism. These features include an herbaceous perennial habit, the ability to regenerate from thickened rootstocks following fires and ex more...
- Published
- 1999
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46. Rheochloa (Poaceae: Chloridoideae), a New Genus from Central Brazil
- Author
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Yolanda Herrera-Arrieta, Paul M. Peterson, and Tarciso S. Filgueiras
- Subjects
education.field_of_study ,Perennial plant ,Ecology ,Population ,Plant Science ,Biology ,biology.organism_classification ,Tribe (biology) ,Raceme ,Genus ,Botany ,Genetics ,Chloridoideae ,Habit (biology) ,education ,Ecology, Evolution, Behavior and Systematics ,Dinebra - Abstract
Rheochloa scabiflora Filg., P.M. Peterson & Y Herrera, gen. et sp. nov., is described and illustrated. The new species occurs in humid grasslands of Municipio de Mineiros, Goias, Parque Nacional das Emas in central Brazil. It seems most closely allied with Dinebra but differs by its perennial habit, inflorescences composed of 3-5 subdigitate racemes, short pedicellate spikelets, glabrous lemmas that are ciliolate on the apex, and fusiform caryopses with persistent style bases. Rheochloa is tentatively placed in subtribe Eragrostidinae of tribe Eragrostideae. So far, R. scabriflora is known only from a single population located inside Parque Nacional das Emas (18?17'55"S-52?43'79"W). more...
- Published
- 1999
- Full Text
- View/download PDF
47. Floral Morphology and Anatomy of Bonnetiaceae
- Author
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William C. Dickison and Anna L. Weitzman
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Gynoecium ,Ecology ,Ovary (botany) ,Stamen ,Petal ,Plant Science ,Anatomy ,Perianth ,Fascicle ,Biology ,Ovule ,Ecology, Evolution, Behavior and Systematics ,Calyx - Abstract
DICKISON, W. C. (Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 275993280) and A. L. WEITZMAN (Department of Botany, Smithsonian Institution, Washington, DC 20560). Floral morphology and anatomy of Bonnetiaceae. J. Torrey Bot. Soc. 125:268-286. 1998.-A detailed study of floral morphology and anatomy of three genera comprising a narrowly circumscribed dicotyledonous family Bonnetiaceae is presented. Flowers are subtended by bracteoles and possess a perianth that is clearly differentiated into a 5-parted calyx and corolla composed of rather thick members. The androecium contains numerous stamens that are united at the base to form a short tube or collar or the stamens are pentadelphous and grouped at the base into five bundles that are positioned in the petal planes. Stamen fascicle traces are reported for the first time in flowers of Bonnetiaceae and are shown to originate close to, or adnate to, the median petal trace. Occasionally, two fascicle bundles arise side by side from a common gap as double bundles. Anther morphology and attachment is variable. Ploiarium possesses nectariferous discs that alternate with the stamen clusters. The presence of nectariferous tissue in Archytaea is variable. Nectaries can be supplied by double bundles, supporting the view that the nectaries of Plioarium and Archytaea represent transformed stamens. Gynoecia are compound, superior, and 3-carpellate or 5-carpellate. Styles range from divided to the base to undivided, and uniformly have a papillate stigma and a central canal filled with transfusion tissue. Placentation changes from axile to essentially parietal at midlevel of the ovary. Ovules are bitegmic, and contrasted with the putatively closely related Theaceae in which the elongated inner integument forms the micropyle, the outer integument projects well beyond the inner one. In addition to the degree of style fusion and carpel number, other important differences among genera of Bonnetiaceae are found in anther wall structure and floral vascular patterns. Major features of variation in the floral vascular system relate to the number and degree of independence of sepallary and petal traces; degree of independence of the androecial vascularization; the organization of the central ovarian vascular system; and the condition of the stylar vasculature. Comparisons are made among the flowers of Bonnetiaceae, Theaceae and Cluisiaceae. more...
- Published
- 1998
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48. Foliar Idioblasts in Physostegia virginiana (Lamiaceae)
- Author
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John D. Curtis and Nels R. Lersten
- Subjects
Ecology ,Idioblast ,biology ,Plant Science ,Physostegia ,biology.organism_classification ,Vascular bundle ,Trichome ,Botany ,Lamiaceae ,Literature survey ,Oil storage ,Leaf development ,Ecology, Evolution, Behavior and Systematics - Abstract
LERSTEN, NELS R. (Department of Botany, Iowa State University, Ames, IA 50011) AND JOHN D. CURTIS (Biology Department, University of Wisconsin-Stevens Point, Stevens Point, WI 54481). Foliar idioblasts in Physostegia virginiana (Lamiaceae). J. Torrey Bot. Soc. 125:133-137. 1998-A literature survey of internal oil secretion in Lamiaceae revealed that only Brazoria and Physostegia have greatly enlarged foliar mesophyll idioblasts. These have been regarded as specialized oil storage cells that evolved independently of oil cells in other angiosperm families. Resin sections and scanning electron microscope preparations of mature Physostegia virginiana (L.) Benth. leaves showed that each idioblast is an unusually large ellipsoid cell, which is dead at maturity. Idioblasts occur in all mesophyll layers but are most common in the mid-stratum, often abutting a bundle sheath or even occurring as part of it and bulging conspicuously into the mesophyll. Freehand leaf sections treated with Sudan IV showed one small oil drop per idioblast, a similar oil drop in other mesophyll cells, and a larger oil deposit atop each of the many small capitate secretory epidermal trichomes. Oil accumulation is common among leaf cells, therefore we speculate that the idioblasts may primarily serve a defensive function, one as yet unknown, possibly during leaf development. more...
- Published
- 1998
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49. Intermountain Flora: Vascular Plants of the Intermountain West, U.S.A., Volume 3, Part A, Subclass Rosidae (except Fabales)
- Author
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Ronald L. Hartman, Patricia K. Holmgren, Arthur Cronquist, and Noel H. Holmgren
- Subjects
Flora ,biology ,Ecology ,Botany ,Genetics ,Plant Science ,Fabales ,Rosidae ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics - Published
- 1998
- Full Text
- View/download PDF
50. Defoliation and Cold-Hardiness of Northern Wheatgrass
- Author
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Brendan L. Kowalenko and James T. Romo
- Subjects
Ecology ,biology ,Late winter ,Tiller (botany) ,biology.organism_classification ,Early winter ,Environmental temperature ,Animal science ,Botany ,Animal Science and Zoology ,Elymus lanceolatus ,Agropyron ,Hardiness (plants) ,Cold stress - Abstract
Freezing temperatures in winter were hypothesized to be a major cause of mortality of tillers following defoliation of northern wheatgrass (Agropyron dasystachyum [Hook.] Scribn., syn. Elymus lanceolatus [Scribn. S 2) exposing them to -15 degrees C for 0 to 15 days. The LT50 (temperature at which 50% of tillers died) of northern wheatgrass tillers in early winter ranged from -29.5 to < -36.0 degrees C in 1992-93, and averaged -24.0 degrees C in 1993-94. In late winter LT50 ranged from -18.1 to -22.6 degrees C in 1992-1993, and it averaged -22.0 degrees C in 1993-1994. The LDur50 (duration at which 50% of tillers died) of tillers exposed to -15 degrees C for 0 to 15 days ranged from 8.0 to 13.1 days in early winter, and 2.7 to 4.7 days in late winter. Unexpectedly mowed tillers were generally more cold-hardy than those from control. In early winter LT50 was 1.5 to 10 degrees C lower for mowed than control tillers. The hypothesis that defoliation reduces cold-hardiness of northern wheatgrass was rejected. The degree or duration of cold stress in the field is generally insufficient to reduce tiller survival in northern wheatgrass. Late winter through early spring is a critical period for tiller survival of northern wheatgrass because cold-hardiness declines this time of the year. Maintaining insulating cover can moderate soil temperatures and reduce damage to plants from freezing temperatures. more...
- Published
- 1998
- Full Text
- View/download PDF
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