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.

/pdf/human-occupation-of-northern-australia-by-65-000-years-ago-57dmyjwcki.pdf

Human occupation of northern Australia by 65,000 years ago

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.

Character States, Morphological Variation, and Phylogenetic Analysis: A Review

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.

The dalbergioid legumes (Fabaceae): delimitation of a pantropical monophyletic clade

Alterations in energy properties of eucalyptus wood and bark subjected to torrefaction: the potential of mass loss as a synthetic indicator.

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 ...

Aluminum Hyperaccumulation in Angiosperms: A Review of Its Phylogenetic Significance

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

IAWA list of microscopic features for softwood identification

The axial variation of bark thickness and quantitative anatomical features of Eucalyptus globulus bark were analysed for one site based on individual measurements of ten 15-year-old trees at six height levels (DBH, 5%, 15%, 35%, 55% and 75% of total tree height). The parameters studied were: length, tangential diameter and percentage of sieve tubes; length, width, cell wall thickness and percentage of fibres; height and percentage of rays; percentage of sclereids in the secondary phloem. Bark thickness decreases from base to top of the tree. Fibre width and wall thickness decrease from base upwards. No distinct axial patterns of variation were observed for the other biometric variables studied. Parenchyma is the main cell type of the bark (50%) followed by fibres (27.9%), rays (12.1%), sieve tubes (2.7%), and sclereids (7.3%). The cell type proportions vary significantly within the tree, i.e., parenchyma, ray and sclereid proportions decrease, fibre and sieve tube proportions increase towards the top of the tree.

/pdf/within-tree-variation-in-phloem-cell-dimensions-and-588m8uick7.pdf

Within-tree variation in phloem cell dimensions and proportions in Eucalyptus globulus.

Sassafrasoxylon gottwaldii sp. nov. is a new taxon for fossil wood with a suite of features diagnostic of Sassafras Nees & Eberm. of the Lauraceae. The fossil wood described is from Late Cretaceous (Santonian- Maastrichtian) sediments of the northern Antarctica Peninsula region. This new species of Sassafrasoxylon Brezinova et Suss resembles the species of extant Sassafras in being distinctly ring-porous, having vessel elements with simple perforation plates and very occasional scalariform plates with relatively few bars in the narrowest latewood vessels, alternate intervascular pitting, marginal (initial) parenchyma bands and paratracheal vasicentric parenchyma in the latewood, multiseriate rays and oil and /or mucilage cells. The fossils were found as isolated pieces of wood and therefore it is not certain whether the parent plant was Sassafras-like in all characters. Consequently the fossils have been placed in an organ genus rather than in extant Sassafras. This is the oldest record of an organ with features closest to extant Sassafras and may suggest that Sassafras first appeared in Gondwana and later radiated into the Northern Hemisphere. The distribution of extant Sassafras in North America and East Asia may represent a relict of a geographically more widespread taxon in the past.

/pdf/evidence-for-gondwanan-origins-for-sassafras-lauraceae-late-i59fm5lant.pdf

Evidence for gondwanan origins for sassafras (lauraceae)? late cretaceous fossil wood of antarctica

Qualitative features of the secondary xylem of Licaria present a rather uniform structural profile. Constant differences in primarily quantitative characters lead to the formation of speeies groups wh ich loosely correspond to infrageneric sections based on floral and vegetative morphology. This subdivision is strongly corroborated by the highly variable secondary phloem structurc revealing considerable diversity in type and distribution of sc1erenchymatic tissues. Inorganic inclusions in the secondary xylem, crystals and silica, constitute an important diagnostic tool for differentiating certain species and species groups, but are hardly of importance in the bark.

Wood and Bark Anatomy of Lauraceae. ii. Licaria Aublet

The bark structure of Eucalyptus globulus Labill. grown in plantations in Central Portugal is described, based on specimens extracted at six height levels from ten 15-year-old trees. No significant variation of qualitative features between trees was observed. The non-collapsed phloem is characterised by multiseriate tangential rows of phloem parenchyma alternating with rows of phloem fibres, interspersed with large sieve tubes and their respective companion cells, and uniseriate rays . With the onset of sieve tube collapse (collapsed phloem ), some parenchyma cells expand and sclerify, the course of rays becomes irregular, and ray dilatation is initiated. The periderm is composed of a phellem of lignified cells with horseshoe thickening (phelloids), followed by a layer of cells with suberised tangential walls, and a phelloderm with a variable number of layers of thin-walled cells. Age-related secondary changes give rise to a specific within-tree pattern of axial variation. Both the intensity of sclerification of phloem parenchyma cells and the degree of ray dilatation increase with tree age.

/pdf/variability-of-bark-structure-in-plantation-grown-eucalyptus-4863s7i7fp.pdf

Hans Georg Richter

Papers

IAWA list of microscopic features for softwood identification

Within-tree variation in phloem cell dimensions and proportions in Eucalyptus globulus.

Evidence for gondwanan origins for sassafras (lauraceae)? late cretaceous fossil wood of antarctica

Wood and Bark Anatomy of Lauraceae. ii. Licaria Aublet

Variability of bark structure in plantation-grown Eucalyptus globulus