Reproductive capability of brushtail possums (Trichosurus vulpecula) transferred from the wilds of Brisbane, Adelaide, and Armidale into captivity in Brisbane

The transfer of animals from the wild into captivity is an important strategy for the conservation of species that are under threat of extinction. To determine the reproductive capability of animals following transfer from the wild, brushtail possums relocated from Brisbane, Adelaide, and Armidale into captivity in Brisbane were monitored. Seventy five percent of the Brisbane possums (N = 80) gave birth during the months from March to May following transfer from the suburbs of Brisbane and 75% of the young born reached weaning. Thirteen adult females and four adult male brushtail possums were relocated from Adelaide into captivity in Brisbane in June 1994. Four young were born in Brisbane, however none survived to weaning and all the relocated possums had died 2 years after their transfer from Adelaide. Seventeen adult females and seven adult male possums were transferred from Armidale to Brisbane in July 1996. In the first year, 1997, four young were born in Brisbane and none survived to weaning. In the second year, three young were born and survived to weaning. Two years after their transfer, one adult male and three adult females from Armidale and three juvenile possums were housed in the Brisbane enclosures. As the Brisbane, Adelaide, and Armidale possums received the same photoperiod and environmental conditions, some factor must have inhibited breeding activity in the Adelaide possums and to a lesser extent in the Armidale possums. The ability of the Armidale possums to give birth and wean their young after 2 years in Brisbane would suggest that relocated possums require up to 2 years in order to adjust sufficiently to their new environment to reproduce. However, the failure of the Adelaide possums to reproduce successfully after a similar period of time in Brisbane suggests that certain environmental differences inhibit the ability of different populations of possums to adjust to a new environment. J. Exp. Zool. 284:783-788, 1999. Copyright 1999 Wiley-Liss, Inc.     

Seasonal distribution of pollen in the atmosphere of melbourne: an airborne pollen calendar

Environmental monitoring of pollen grains in the atmosphere of Melbourne has been achieved using Burkard volumetric traps. Twenty-two families of flowering plants and confiers were identified in the pollen counts. About 62% of these pollen grains belonged to trees, 20% to grasses and 9% to herbs and weedy plants. During spring and summer, the atmosphere contained about 70% of the total annual pollen count. Tree pollen, predominantly elm and cypress, occurred abundantly in late winter and spring, with grass pollen predominantly in spring and early summer. These three types of pollen grains occurred in significant amounts, together accounting for more than 60% of the total annual catch. A seasonal incidence chart (pollen calendar) for Melbourne based on 2 years observation has been constructed. This pollen calendar is useful in identifying sources of allergies against particular seasonal airborne pollen types. Comparison of the time of occurrence of a particular pollen type using the pollen calendar and the time of allergic symptoms, can lead to accurate diagnosis and preventive measures being taken. This study has confirmed that grass pollen is the major source of allergenic pollen in the external environment triggering hay fever and allergic asthma in spring and early summer in Melbourne, Australia.     

Does rapid utilization of elevated nutrient availability allow eucalypts to dominate in the tropical savannas of Australia?

Northern Australia's savannas are among the most fire‐prone biomes on Earth and are dominated by eucalypts (Eucalyptus and Corymbia spp.). It is not clear what processes allow this group to dominate under such extreme fire frequencies and whether a superior ability to compete for nutrients and water might play a role. There is evidence that eucalypts are adapted to frequent fires; juvenile eucalypts escape the fire trap by growing rapidly in height between fires. However, non‐eucalypts are less able to escape the fire trap and tend to have stand structures strongly skewed toward suppressed juveniles. The mechanisms that drive these contrasting fire responses are not well understood. Here, we describe the results of a controlled glasshouse seedling experiment that evaluated the relative importance of nutrient and water availability in determining height growth and biomass growth of two eucalypt and one noneucalypt tree species, common in northern Australian savannas. We demonstrate that growth of eucalypt seedlings is particularly responsive to nutrient addition. Eucalypt seedlings are able to rapidly utilize soil nutrients and accumulate biomass at a much greater rate than noneucalypt seedlings. We suggest that a seasonal spike in nutrient availability creates a nutrient‐rich microsite that allows eucalypt seedlings to rapidly gain height and biomass, increasing their likelihood of establishing successfully and reaching a fire‐resistant size. Our results extend our understanding of how eucalypts dominate northern Australian savannas under extremely high fire frequencies.     

Genetic differentiation among various populations of the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae)

Genetic variation among 14 populations of Plutella xylostella (Linnaeus) from USA (Geneva, New York), Brazil (Brasilia), Japan (Okayama), The Philippines (Caragan de Oyo), Uzbekistan (Tashkent), France (Montpellier), Benin (Cotonou), South Africa (Johannesburg), Réunion Island (Montvert), and five localities in Australia (Adelaide, Brisbane, Mareeba, Melbourne, Sydney) were assessed by analysis of allozyme frequencies at seven polymorphic loci. Most of the populations were not in Hardy-Weinberg equilibrium and had a deficit in heterozygotes. The global differentiation among populations was estimated by the fixation index (Fst) at 0.103 for the 14 populations and at 0.047 when populations from Australia and Japan, which differed most and had a strong genetic structure, were excluded from the analysis. By contrast, the populations from Benin (West Africa) and Brazil (South America) were very similar to each other. Genetic differentiation among the populations was not correlated with geographical distance.     

Localisation of allergens in ryegrass pollen and in airborne micronic particles

Summary In Melbourne, Australia, grass pollen allergens, especially from ryegrass, are a major cause of allergic hayfever and asthma. This review outlines recent developments in our understanding of how grass pollen allergens find their way into the atmosphere and how they are transported in particulate form. Much of this work has relied on antibody technology in immunological and immunocytochemical investigations. The localisation of allergens in situ has proved difficult due to their water-soluble character. Recently, allergens have been localised in developing ryegrass pollen by dryfixation, rapid-freeze and freeze-substitution techniques. This involved anthers being substituted in a mixture of aldehydes, organic solvents, and 2,2-dimethoxypropane. Incubation in dimethylsulfoxide prior to embedding in LR Gold resin provided good infiltration with freeze-substituted material. Immunogold-labelled sections show that the major allergens, Lol p 1 and Lol p 5, are synthesised in the pollen cytoplasm from the early bicellular stage, soon after the first starch granules are formed. From the early tricellular stage, Lol p 5 moves into the starch granules where it remains until maturity. Lol p 1 is localised in the cytoplasm of mature pollen grains. The incidence of airborne grass pollen, as measured in pollen traps, correlates with hayfever symptoms. Forecasting models which rely on rainfall and temperature data have been produced for the grass pollen (daily and seasonal) counts in Melbourne. Research over the past six years has shed light on the causes of grass-pollen-induced asthma. Micronic particles in the atmosphere may be starch granules originating from pollen grains osmotically ruptured by rainwater. Ultrastructural and immunological characterisation of micronic particles collected from outdoor air filters confirm the presence of airborne starch granules. These are loaded with grass pollen allergens, occur in the atmosphere especially after rainfall, and correlate significantly with instances of allergic asthma. Diesel particles might also play a role in the transmission of grass pollen allergens and thus become an extra asthma trigger. A variation in the mode of release of micronic particles occurs in other species, such as birch, where such particles are derived from burst birch pollen tubes. These particles are positive for Bet v 1 and are starch granules which are released into the atmosphere after light rain as a result of pollen germination on, e.g., leaves. After subsequent rupture of pollen tubes their contents are released when conditions become drier.Abbreviations DECP diesel exhaust carbon particles - DMP 2,2-dimethoxypropane - GPC grass pollen count - IgE immunoglobulin E - IgG immunoglobulin G - OGPS onset of the grass pollen season     

Factors affecting the growth of Eucalyptus delegatensis seedlings in inhibitory forest and grassland soils

In many highland forests of Eucalyptus delegatensis in Tasmania the establishment and healthy growth of eucalypts is promoted and maintained by fire. In the absence of fire, secondary succession from eucalypt forest to rainforest occurs, during which the eucalypts decline and die prematurely. On sites that are prone to radiation frost severe reduction or removal of a tree canopy allows a sward of tussock grasses to develop, in competition with which seedlings of eucalypts decline in growth and a high proportion dies.Factors of the soil that could contribute to these phenomena were investigated by means of pot experiments that used soils from:o     

Patterns of tree species richness in relation to environment in southeastern New South Wales,Australia

Abstract We present regression models of species richness for total tree species, two growth forms, rainforest trees (broadleaf evergreens) and eucalypts (sclerophylls), and two large subgenera of Eucalyptus. The correlative models are based on a data set of 166 tree species from 7208 plots in an area of southeastern New South Wales, Australia. Eight environmental variables are used to model the patterns of species richness, four continuous variables (mean annual temperature, rainfall, radiation and plot size), plus four categorical factors (topographic position, lithology, soil nutrient level and rainfall seasonality). Generalized linear modelling with curvilinear and interaction terms, is used to derive the models. Each model shows a significant and differing response to the environmental predictors. Maximum species richness of eucalypts occurs at high temperatures, and intermediate rainfall and radiation conditions on ridges with aseasonal rainfall and intermediate nutrient levels. Maximum richness of rainforest species occurs at high temperatures, intermediate rainfall and low radiation in gullies with summer rainfall and high nutrient levels. The eucalypt subgenera models differ in ways consistent with experimental studies of habitat preferences of the subgenera. Curvilinear and interaction terms are necessary for adequate modelling. Patterns of richness vary widely with taxonomic rank and growth form. Any theories of species diversity should be consistent with these correlative models. The models are consistent with an available energy hypothesis based on actual evapotranspiration. We conclude that studies of species richness patterns should include local (e.g. soil nutrients, topographic position) and regional (e.g. mean annual temperature, annual rainfall) environmental variables before invoking concepts such as niche saturation.     

Stop the bullying in the corridors: Can including shrubs make your revegetation more Noisy Miner free?

Summary   Noisy Miners ( Manorina melanocephala ) are aggressive Australian honeyeaters that dominate many areas of remnant vegetation and forest edges from which they competitively exclude small birds. A similar domination can also occur in planted wildlife corridors. The aim of this study was to determine which corridor plantings encouraged the presence of small native birds in regions where Noisy Miners dominate. Six vegetation mixes were investigated in the main study: eucalypts with and without shrubby understorey; acacia with and without shrubby understorey; exotic conifer; and exotic deciduous trees. A supplementary study then examined sites with a mixture of eucalypt and acacia trees with a shrubby understorey. The findings showed that Noisy Miners dominated corridors of eucalypts, virtually excluding small birds, whereas native acacias, exotic conifer and exotic deciduous corridors had small birds and no resident Noisy Miners. The greatest abundance and richness of small birds occurred in plantings combining eucalypts with at least 15% acacias, in this case bipinnate species. Given these results, it is recommended that eucalypt plantings should be supplemented with both acacias (preferably bipinnate) and a shrubby understorey.     

Insect damage in Eucalyptus: A review of plantations in Chile

Chile has more than 330 000 ha of eucalypt plantations, predominantly in the eighth to the tenth region (approximately 34 to 41°S). Eucalyptus globulus ssp. globulus is the principal eucalypt planted, but Eucalyptus nitens, Eucalyptus camaldulensis, Eucalyptus delegatensis and Eucalyptus viminalis are also grown. There are four main insect pests that have been detected attacking these eucalypts in Chile: the defoliator Gonipterus scutellatus, the bark borers Phoracantha semipunctata and Phoracantha recurva and the native wood borer Chilecomadia valdiviana. More recently, Thyrinteina arnobia and Ctenarytaina eucalypti have been detected. Gonipterus scutellatus and P. recurva have been discovered in Chile within the last 2 years and it is hoped they may still be eliminated using a combination of biological control and chemical control of local populations. Phoracantha recurva and P. semipunctata are not considered a problem because attack only occurs in areas of water deficit, away from current eucalypt plantations. Chilecomadia valdiviana can damage plantations of E. nitens but rarely attacks other eucalypts.?Chilecomadia valdiviana may cause future problems through further host shifts. Thyrinteina arnobia has only been detected during quarantine surveillance in the port of Valparaiso. Ctenarytaina eucalypti, recently detected in August 1999, had an initial limited distribution in the first region. However, since then, this insect has expanded its distribution south up to the tenth region. None of the insects recorded on eucalypts in Chile to date currently presents a threat to the eucalypt industry. It is also essential that additional resources are made available for their continued monitoring and control, particularly given that the 44% of plantations are held by small to medium property owners that would otherwise be unable to control a serious outbreak because of economic restrictions.     

Rust disease of eucalypts,caused by Puccinia psidii,did not originate via host jump from guava in Brazil

The rust fungus, Puccinia psidii, is a devastating pathogen of introduced eucalypts (Eucalyptus spp.) in Brazil where it was first observed in 1912. This pathogen is hypothesized to be endemic to South and Central America and to have first infected eucalypts via a host jump from native guava (Psidium guajava). Ten microsatellite markers were used to genotype 148 P. psidii samples from eucalypts and guava plus five additional myrtaceous hosts across a wide geographic range of south‐eastern Brazil and Uruguay. Principal coordinates analysis, a Bayesian clustering analysis and a minimum‐spanning network revealed two major genetic clusters among the sampled isolates, one associated with guava and another associated with eucalypts and three additional hosts. Multilocus genotypes infecting guava differed by multiple mutational steps at eight loci compared with those infecting eucalypts. Approximate Bayesian computation revealed that evolutionary scenarios involving a coalescence event between guava‐ and eucalypt‐associated pathogen populations within the past 1000 years are highly unlikely. None of the analyses supported the hypothesis that eucalypt‐infecting P. psidii in Brazil originated via host jump from guava following the introduction of eucalypts to Brazil approximately 185 years ago. The existence of host‐associated biotypes of P. psidii in Brazil indicates that this diversity must be considered when assessing the invasive threat posed by this pathogen to myrtaceous hosts worldwide.     

Fire,storm, flood and drought: The vegetation ecology of Howards Peninsula,Northern Territory,Australia

Twenty different communities, characteristic of the coastal vegetation of the northern portion of the Northern Territory, were recognized by photo-interpretation and ground truthing a 20 × 20 km area near Darwin. Data collected from 161 quadrats placed throughout the study area showed a strong relationship between subjective and objective measures of vegetation structure. Photopattern is best explained by a combination of structural, lifeform and floristic data. The mangrove, grassland, forest and woodland communities form a complex spatial pattern. Variations in moisture regime, through the interaction of topography and soils with temporal fluctuations of salt and/or fresh water supply, appear to best explain vegetation distribution. Three anomalously open eucalypt communities are interpreted as being the consequence of a severe tropical cyclonic storm which destroyed much of Darwin in 1974. These communities are frequently burnt by the nearby urban population and possess layers of sapling size eucalypts, although the height and density of the regrowth appears to vary with site quality. It is argued that fire is a characteristic of the seasonal climate, and that the fire pattern largely reflects the vegetation pattern. Occasional severe tropical storms also affect vegetation types differently. The greatest amount of windthrow occurs in moist monsoon forests while the eucalypts on well drained soils are more windfirm, but remain obviously damaged for over 10 years.     

Climate and geochemistry as drivers of eucalypt diversification in Australia

Eucalypts cover most of Australia. Here, we investigate the relative contribution of climate and geochemistry to the distribution and diversity of eucalypts. Using geostatistics, we estimate major element concentrations, pH, and electrical conductivity at sites where eucalypts have been recorded. We compare the median predicted geochemistry and reported substrate for individual species that appear associated with extreme conditions; this provides a partial evaluation of the predictions. We generate a site‐by‐species matrix by aggregating observations to the centroids of 100‐km‐wide grid cells, calculate diversity indices, and use numerical ecology methods (ordination, variation partitioning) to investigate the ecology of eucalypts and their response to climatic and geochemical gradients. We find that β‐diversity coincides with variations in climatic and geochemical patterns. Climate and geochemistry together account for less than half of the variation in eucalypt species assemblages across Australia but for greater than 80% in areas of high species richness. Climate is more important than geochemistry in explaining eucalypts species distribution and change in assemblages across Australia as a whole but there are correlations between the two sets of environmental variables. Many individual eucalypt species and entire taxonomic sections (Aromatica, Longistylus of subgenus Eucalyptus, Dumaria, and Liberivalvae of subgenus Symphyomyrtus) have distributions affected strongly by geochemistry. We conclude that eucalypt diversity is driven by steep geochemical gradients that have arisen as climate patterns have fluctuated over Australia over the Cenozoic, generally aridifying since the Miocene. The diversification of eucalypts across Australia is thus an excellent example of co‐evolution of landscapes and biota in space and time and challenges accepted notions of macroecology.     

Water stress,leaf nutrients and defoliation: a model of dieback of rural eucalypts

Water stress, concentrations of foliar nutrients and damage of foliage by insects were studied over an eleven month period, for eight dieback eucalypts and eight closely matched healthy trees growing in close association on two grazing properties near Brisbane. Four healthy eucalypts in a neighbouring State Forest were also studied. The study region had suffered severe climatic stress between 1972 and 1976 when dieback was first observed by residents and when high populations of defoliating insects were observed. Dieback trees had a higher proportion of foliage damaged by insects and higher concentrations of foliar nutrients than did matched healthy trees. The study period was one of low climatic stress during which dieback and healthy trees followed similar seasonal patterns of predawn xylem pressure potential. Dieback trees developed lower daytime minimum xylem pressure potentials than did matched healthy trees, and differed in their stomatal responses. A model of initiation and development of rural eucalypt dieback is proposed. This may have general application to many non-specific rural diebacks in which heavy insect damage is implicated. The balance between rural eucalypts and their insect herbivores is precarious. Any factor capable of causing extensive defoliation, or an increase in foliar nitrogen, or an increase in populations of insect herbivores may upset this balance. A positive feedback loop may be activated, whereby the production of nitrogen rich epicormic foliage enhances a build up of insect populations. Repeated insect defoliation leads to tree dieback. Evidence in the literature supporting the model is reviewed and aspects requiring further research are outlined.     

The annual variation of asthma in Brisbane: Its relation to the weather

A study has been made of the annual incidence of asthma in Brisbane for 7 years in relation to the weather. The element most closely associated with asthma was rainfall. There was a minor, independent association with temperature. The association of asthma with rain and warmth, which promote the growth of vegetation, supports the suggestion arising from the seasonal study of asthma that vegetation may be an important source of allergens.

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Zusammenfassung Die Beziehung zwischen dem Wetter und der Häufigkeit von Asthma in Brisbane während 7 Jahren wurde untersucht. Unter den meteorologischen Elementen ergab sich die engste Beziehung zwischen Asthmahäufigkeit und Niederschlägen. Eine geringere, unabhängige Beziehung bestand mit der Temperatur. Die Verbindung von Asthma mit Niederschlägen und Wärme stützt die Vermutung, dass die Vegetation eine wichtige Allergenquelle ist.

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Resume On a étudié durant 7 années la relation existant entre le temps et la fréquence des crises d'asthme à Brisbane. Parmi les éléments météorologiques examinés, celui qui donna la plus étroite relation est la précipitation.Une relation indépendante, moindre il est vrai, existe également avec la température.L'étroite relation entre les crises d'asthme d'une part, les précipitations et la chaleur d'autre part renforce l'hypothèse que la végétation est la principale source des principes allergènes.

     

Invasion biology of Australian ectomycorrhizal fungi introduced with eucalypt plantations into the Iberian Peninsula

In the last two centuries, several species of Australian eucalypts (e.g. Eucalyptus camaldulensis and E.␣globulus) were introduced into the Iberian Peninsula for the production of paper pulp. The effects of the introduction of exotic root-symbitotic fungi together with the eucalypts have received little attention. During the past years, we have investigated the biology of ectomycorrhizal fungi in eucalypt plantations in the Iberian Peninsula. In the plantations studied, we found fruit bodies of several Australian ectomycorrhizal fungi and identified their ectomycorrhizas with DNA molecular markers. The most frequent species were Hydnangium carneum, Hymenogaster albus, Hysterangium inflatum, Labyrinthomyces donkii, Laccaria fraterna, Pisolithus albus, P. microcarpus, Rhulandiella berolinensis, Setchelliogaster rheophyllus, and Tricholoma eucalypticum. These fungi were likely brought from Australia together with the eucalypts, and they seem to have facilitated the establishment of eucalypt plantations and their naturalization. The dispersion of Australian fungal propagules may be facilitating the spread of eucalypts along watercourses in semiarid regions increasing the water lost. Because ectomycorrhizal fungi are obligate symbionts, their capacity to persist after eradication of eucalypt stands, and/or to extend beyond forest plantations, would rely on the possibility to find compatible native host trees, and to outcompete the native ectomycorrhizal fungi. Here we illustrate the case of the Australasian species Laccaria fraterna, which fruits in Mediterranean shrublands of ectomycorrhizal species of Cistus (rockroses). We need to know which other Australasian fungi extend to the native ecosystems, if we are to predict environmental␣risks associated with the introduction of Australasian ectomycorrhizal fungi into the Iberian Peninsula. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photosynthetic nitrogen and water use efficiency of acacia and eucalypt seedlings as afforestation species

The ecophysiological traits of acacia and eucalypt are important in assessing their suitability for afforestation. We measured the gas-exchange rate, the leaf dry mass per area (LMA) and the leaf nitrogen content of two acacia and four eucalypt species. Relative to the eucalypts, the acacias had lower leaf net photosynthetic rate (P _N), lower photosynthetic nitrogen-use efficiency (PNUE), higher water-use efficiency (WUE), higher LMA and higher leaf nitrogen per unit area (N _area). No clear differences were observed within or between genera in the maximum rate of carboxylation (V _cmax) or the maximum rate of electron transport (J _max), although these parameters tended to be higher in eucalypts. PNUE and LMA were negatively correlated. We conclude that acacias with higher LMA do not allocate nitrogen efficiently to photosynthetic system, explaining why their P _N and PNUE were lower than in eucalypts.     

Exposure to preindustrial, current and future atmospheric CO2 and temperature differentially affects growth and photosynthesis in Eucalyptus

To investigate if Eucalyptus species have responded to industrial-age climate change, and how they may respond to a future climate, we measured growth and physiology of fast- ( E. saligna ) and slow-growing ( E. sideroxylon ) seedlings exposed to preindustrial (290), current (400) or projected (650 μL L⁻¹) CO₂ concentration ([CO₂]) and to current or projected (current +4 °C) temperature. To evaluate maximum potential treatment responses, plants were grown with nonlimiting soil moisture. We found that: (1) E. sideroxylon responded more strongly to elevated [CO₂] than to elevated temperature, while E. saligna responded similarly to elevated [CO₂] and elevated temperature; (2) the transition from preindustrial to current [CO₂] did not enhance eucalypt plant growth under ambient temperature, despite enhancing photosynthesis; (3) the transition from current to future [CO₂] stimulated both photosynthesis and growth of eucalypts, independent of temperature; and (4) warming enhanced eucalypt growth, independent of future [CO₂], despite not affecting photosynthesis. These results suggest large potential carbon sequestration by eucalypts in a future world, and highlight the need to evaluate how future water availability may affect such responses.     

Niche differentiation and maintenance of genetic identity in cohabiting Eucalyptus species

Differences in niche utilization between two cohabiting eucalypt species (Eucalyptus signata and E. umbra ssp. umbra) on North Stradbroke Island, Qld., are documented, including differences in morphology, growth patterns, seasonality, insect attack and a three month difference in peak seasonal uptake of most essential elements. The significance of these niche differences in aiding the coexistence of competing eucalypt species is supported by results using recent theoretical models from niche theory. It is noted that the presence of significant niche complementarity amongst cohabiting pairs of eucalypts will place hybrid offspring at a disadvantage relative to homozygous strains. This phenomenon helps explain the scarcity or absence of hybrids in a number of communities where potentially interbreeding species of Eucalyptus coexist. Co-occurrence of species pairs which are capable of interbreeding will not be favored by environmental selection both because of the reduced production of homozygous offspring, and because of the reduced niche separation exhibited by taxonomically closely-related species. Such differences help explain the scarcity of co-occurrence of interbreeding pairs of species of Eucalyptus in relatively unperturbed natural communities.     

Floral development and systematic position of <Emphasis Type="Italic">Arillastrum</Emphasis>, <Emphasis Type="Italic">Allosyncarpia</Emphasis>, <Emphasis Type="Italic">Stockwellia</Emphasis> and <Emphasis Type="Italic">Eucalyptopsis</Emphasis> (Myrtaceae)

We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.     

Eucalypt MADS-Box Genes Expressed in Developing Flowers

Three MADS-box genes were identified from a cDNA library derived from young flowers of Eucalyptus grandis W. Hill ex Maiden. The three egm genes are single-copy genes and are expressed almost exclusively in flowers. The egm1 and egm3 genes shared strongest homology with other plant MADS-box genes, which mediate between the floral meristem and the organ-identity genes. The egm3 gene was also expressed strongly in the receptacle or floral tube, which surrounds the carpels in the eucalypt flower and bears the sepals, petals, and numerous stamens. There appeared to be a group of genes in eucalypts with strong homology with the 3′ region of the egm1 gene. The egm2 gene was expressed in eucalypt petals and stamens and was most homologous to MADS-box genes, which belong to the globosa group of genes, which regulate organogenesis of the second and third floral whorls. The possible role of these three genes in eucalypt floral development is discussed.