IAWA list of microscopic features for softwood identification
TL;DR: This poster presents a selection of photographs from around the world taken in the period of May 21 to 29, 1997, as well as some of the more recent photographs taken in China and the United States.
Abstract: Pieter Baas – Leiden, The Netherlands Nadezhda Blokhina – Vladivostok, Russia Tomoyuki Fujii – Ibaraki, Japan Peter Gasson – Kew, UK Dietger Grosser – Munich, Germany Immo Heinz – Munich, Germany Jugo Ilic – South Clayton, Australia Jiang Xiaomei – Beijing, China Regis Miller – Madison, WI, USA Lee Ann Newsom – University Park, PA, USA Shuichi Noshiro – Ibaraki, Japan Hans Georg Richter – Hamburg, Germany Mitsuo Suzuki – Sendai, Japan Teresa Terrazas – Montecillo, Mexico Elisabeth Wheeler – Raleigh, NC, USA Alex Wiedenhoeft – Madison, WI, USA
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University of Queensland1, University of Wollongong2, Australian Research Council3, University of Washington4, University of Notre Dame5, National Museum of Australia6, Harvard University7, University of Adelaide8, Australian Nuclear Science and Technology Organisation9, Griffith University10, Australian Synchrotron11, Australian National University12
TL;DR: The results of new excavations conducted at Madjedbebe, a rock shelter in northern Australia, set a new minimum age of around 65,000 years ago for the arrival of humans in Australia, the dispersal of modern humans out of Africa, and the subsequent interactions ofmodern humans with Neanderthals and Denisovans.
Abstract: The time of arrival of people in Australia is an unresolved question. It is relevant to debates about when modern humans first dispersed out of Africa and when their descendants incorporated genetic material from Neanderthals, Denisovans and possibly other hominins. Humans have also been implicated in the extinction of Australia’s megafauna. Here we report the results of new excavations conducted at Madjedbebe, a rock shelter in northern Australia. Artefacts in primary depositional context are concentrated in three dense bands, with the stratigraphic integrity of the deposit demonstrated by artefact refits and by optical dating and other analyses of the sediments. Human occupation began around 65,000 years ago, with a distinctive stone tool assemblage including grinding stones, ground ochres, reflective additives and ground-edge hatchet heads. This evidence sets a new minimum age for the arrival of humans in Australia, the dispersal of modern humans out of Africa, and the subsequent interactions of modern humans with Neanderthals and Denisovans. Optical dating of sediments containing stone artefacts newly excavated at Madjedbebe, Australia, indicate that human occupation began around 65,000 years ago, thereby setting a new minimum age for the arrival of people in Australia. When did humans first colonize Australia? The date of the initial landing on the continent that is now associated with cold lager and 'Waltzing Matilda' has been highly controversial. Dates from a site called Madjedbebe in northern Australia had put the presence of modern humans in Australia at between 60,000 and 50,000 years ago, but these results have since been hotly contested. Here, the results from a comprehensive program of dating of new excavations at the site confirm that people first arrived there around 65,000 years ago. The results show that humans reached Australia well before the extinction of the Australian megafauna and the disappearance of Homo floresiensis in neighbouring Indonesia.
597 citations
TL;DR: It is shown here that a majority of the character states of obviously quantitative characters used in lower-level cladistic studies in botany over the last generation are ambiguous even when ingroup variation alone is analyzed.
Abstract: The step in cladistic analysis that has received least attention is delimitation of char- acter states, there usually being little justification for their delimitation. It is generally assumed that states of cladistic characters are discrete, even when variation is quantitative. I show here that a majority of the character states of obviously quantitative characters used in lower-level cladistic studies in botany over the last generation are ambiguous even when ingroup variation alone is analyzed. Consideration of variation in the outgroup may compromize either the states recognized in the ingroup and/or the polarity that they are subsequently assigned. Furthermore, many so- called qualitative characters are based on a quantitative phenomenological base filtered through the reified semantic discontinuities of botanical terminology; such characters face the problems of their more obviously quantitative relatives. Methods for delimiting states within quantitative char- acters are examined. Some produce gaps in the variation by redefining the character, scoring the intermediates in a distinctive fashion, performing phylogenetic analyses within the terminal taxa, or changing the hierarchical level at which the variation is evaluated. Others produce states by manipulation of the statistical properties of the variation of the ensemble of taxa being studied. These latter methods often allow greater resolution of the phylogeny, but at the cost of lowering the significance of the most parsimonious tree. The underlying assumptions of the two sets of methods are briefly analyzed. Problems manifest in the division of continuous variation into char- acter states suggest a reappraisal of the early steps of cladistic analysis; in practice, character states often seem to be delimited in conjunction with developing ideas of the phylogeny, rather than in a step prior to a phylogenetic analysis. It is recommended that character states be delimited by carefully analyzed discontinuities (not necessarily absolute gaps) in the variation, attention having been paid to variation in the outgroup, and that "morphological" characters in general are assumed to be quantitative unless demonstrated otherwise. Explicit justification for the delimitation of char- acter states should be given as a matter of course in all phylogenetic studies.
287 citations
TL;DR: A monophyletic pantropical group of papilionoid legumes is circumscribed to include all genera previously referred to the tribes Aeschynomeneae and Adesmieae, the subtribe Bryinae of the Desmodieae, and tribe Dalbergieae except Andira, Hymenolobium, Vatairea, and Vatairesopsis.
Abstract: A monophyletic pantropical group of papilionoid legumes, here referred to as the ‘‘dalbergioid’’ legumes, is circumscribed to include all genera previously referred to the tribes Aeschynomeneae and Adesmieae, the subtribe Bryinae of the Desmodieae, and tribe Dalbergieae except Andira, Hymenolobium, Vatairea,and Vataireopsis. This previously undetected group was discovered with phylogenetic analysis of DNA sequences from the chloroplast trnK (including matK) and trnL introns, and the nuclear ribosomal 5.8S and flanking internal transcribed spacers 1 and 2. All dalbergioids belong to one of three well-supported subclades, the Adesmia, Dalbergia, and Pterocarpus clades. The dalbergioid clade and its three main subclades are cryptic in the sense that they are genetically distinct but poorly, if at all, distinguished by nonmolecular data. Traditionally important taxonomic characters, such as arborescent habit, free stamens, and lomented pods, do not provide support for the major clades identified by the molecular analysis. Short shoots, glandular-based trichomes, bilabiate calyces, and aeschynomenoid root nodules, in contrast, are better indicators of relationship at this hierarchical level. The discovery of the dalbergioid clade prompted a re-analysis of root nodule structure and the subsequent finding that the aeschynomenoid root nodule is synapomorphic for the dalbergioids.
252 citations
TL;DR: The preliminary conclusions support the primitive status of aluminum hyperaccumulation, which provides an evolutionary model system for the integration of different biological disciplines, such as systematics, ecology, biogeography, physiology, and biochemistry.
Abstract: Aluminum phytotoxicity and genetically based aluminum resistance has been studied intensively during recent decades because aluminum toxicity is often the primary factor limiting crop productivity on acid soils. Plants that grow on soils with high aluminum concentrations employ three basic strategies to deal with aluminum stress. While excluders effectively prevent aluminum from entering their aerial parts over a broad range of aluminum concentration in the soil, hyperaccumulators take up aluminum in their aboveground tissues in quantities above 1000 ppm; that is, far exceeding those present in the soil or in the nonaccumulating species growing nearby. In between these two extremes are indicator species, representing intermediate responses. A list of aluminum hyperaccumulators in angiosperms is compiled on the basis of data in the literature. Aluminum hyperaccumulators include mainly woody, perennial taxa from tropical regions. Recent molecular phylogenies are used to evaluate the systematic and ...
246 citations
TL;DR: To make wood taxonomy easier to apply, some clarity on terminology not covered by the IAWA Committee is provided and a list of microscopic features for softwood identification is produced.
236 citations
References
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TL;DR: Character of the tissue associated with the ducts and its interpretation and distribution at wounds andPhylogenetic interpretations and fossil evidence are presented.
Abstract: PAGE Introduction II Origin of the resin ducts and associated tissue 2I Character of the tissue associated with the ducts I4 Character and distribution of ducts at wounds . 2I The distribution of ducts and its interpretation 28 Phylogenetic considerations . 32 Comparison of the responses to wounding in the seedling and the adult 34 Relation between the response to wounding and cambial age 37 Comparison of the responses to wounding in different genera 40 Phylogenetic interpretations and fossil evidence 42 Summary 44 References 45
167 citations
118 citations
"IAWA list of microscopic features f..." refers methods in this paper
...(1987) for measuring techniques, and Dinwoodie (1961) and Sudo (1968) for trends in spruce (Picea)....
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01 Jan 1990
TL;DR: The natural weathering process causes exposed wood to discolour and degrade through the effect of light, moisture and staining micro-organisms as mentioned in this paper, but since light does not penetrate wood deeper than 200 mm, degradations reactions are a surface phenomenon.
Abstract: The natural weathering process causes exposed wood to discolour and degrade through the effect of light, moisture and staining micro-organisms Physical deterioration means surface roughening, checking and cracking Chemical deterioration involves a complex sequence of free radical reactions However, since light does not penetrate wood deeper than 200 mm, degradations reactions are a surface phenomenon Consequently wood can be protected by paints, stains and similar materials The influence outdoor weathering on the performance of wood is discussed in detail The chemical and physical changes of wood exposed outdoors are described, and the mechanisms of weathering and methods for protecting exposed wood surfaces are summarised The research described does have implications for the preservation of historic structures
114 citations
"IAWA list of microscopic features f..." refers background in this paper
...Helical thickenings may also be confused with the often helical structure of soft rot cavities in cell walls caused by the enzymatic action of wood destroying fungi (Phillips 1948), or spiral etchings caused by chemical degradation in the surface layers of weathered timber (Feist 1990)....
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Book•
01 Jan 1948
109 citations
"IAWA list of microscopic features f..." refers background in this paper
..., Cupressus arizonica, Sequoia, Thujopsis dolabrata (Phillips 1948)....
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...For further examples of fragrant coniferous woods consult Phillips (1948) and Panshin & DeZeeuw (1980)....
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...khasya); very small denticulations also occur in a few species of Picea (Phillips 1948)....
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...In Cupressaceae the nodular appearance is due to localised thickening of the primary wall, and is not due to pitting in the strict sense, whereas in Abies, Cathaya, Keteleeria, Larix, Picea, Pseudotsuga, Tsuga, a similar appearance is produced by true simple pitting of the secondary wall (Phillips 1948)....
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...Helical thickenings may also be confused with the often helical structure of soft rot cavities in cell walls caused by the enzymatic action of wood destroying fungi (Phillips 1948), or spiral etchings caused by chemical degradation in the surface layers of weathered timber (Feist 1990)....
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