Angophora Species Research Articles

Chloroplast Distribution in the Stems of 23 Eucalypt Species.

Small diameter branchlets and smooth barked stems and branches of most woody plants have chloroplasts. While the stems of several eucalypt species have been shown to photosynthesise, the distribution of chloroplasts has not been investigated in detail. The distribution of chloroplasts in branchlets (23 species) and larger diameter stems and branches with smooth bark (14 species) was investigated in a wide range of eucalypts (species of Angophora, Corymbia and Eucalyptus) using fresh hand sections and a combination of bright field and fluorescence microscopy. All species had abundant stem chloroplasts. In both small and large diameter stems, the greatest concentration of chloroplasts was in a narrow band (usually 100–300 μm thick) immediately beneath the epidermis or phellem. Deeper chloroplasts were present but at a lower density due to abundant fibres and sclereids. In general, chloroplasts were found at greater depths in small diameter stems, often being present in the secondary xylem rays and the pith. The cells of the chlorenchyma band were small, rounded and densely packed, and unlike leaf mesophyll. A high density of chloroplasts was found just beneath the phellem of large diameter stems. These trees gave no external indication that green tissues were present just below the phellem. In these species, a thick phellem was not present to protect the inner living bark. Along with the chlorenchyma, the outer bark also had a high density of fibres and sclereids. These sclerenchyma cells probably disrupted a greater abundance and a more organised arrangement of the cells containing chloroplasts. This shows a possible trade-off between photosynthesis and the typical bark functions of protection and mechanical strength.

Rarity or decline: Key concepts for the Red List of Australian eucalypts

The 822 eucalypt species (Angophora, Corymbia, Eucalyptus) within Australia were assessed using IUCN Red List Categories and Criteria. Overall, 193 (23%) eucalypts qualified as threatened and 36 were considered Data Deficient. One hundred and thirty-four threatened species qualified under criterion A2, representing a past and irreversible population decline of >30%. The remainder were narrow-range species with ongoing threats (mostly mining or urbanisation), or naturally rare. Habitat conversion to crops and pastures was the cause of decline for most threatened eucalypts. Threatened species were concentrated where deforestation and high eucalypt richness coincide, especially south-western Western Australia. Corymbia or Angophora species, and relatively few tropical eucalypts are threatened. Fire, timber harvesting and disease were rarely sufficient threats to eucalypts to warrant a threatened status. Sheep grazing limits regeneration in temperate woodlands, but requires further quantification for individual species. Prior to this study, 89 eucalypts were listed as threatened under Australian environmental law. This assessment recommends that 32 of these species be downgraded to Near Threatened or Least Concern. A further 11 species were identified as Data Deficient, while an additional 147 species were proposed for listing as threatened. This systematic assessment of Australian eucalypts emphasises the importance of decline rather than rarity when compared with previous listings, with broad implications for listing long-lived plants in deforested landscapes.

Chloroplast variation is incongruent with classification of the Australian bloodwood eucalypts (genus Corymbia, family Myrtaceae).

Previous molecular phylogenetic analyses have resolved the Australian bloodwood eucalypt genus Corymbia (~100 species) as either monophyletic or paraphyletic with respect to Angophora (9–10 species). Here we assess relationships of Corymbia and Angophora using a large dataset of chloroplast DNA sequences (121,016 base pairs; from 90 accessions representing 55 Corymbia and 8 Angophora species, plus 33 accessions of related genera), skimmed from high throughput sequencing of genomic DNA, and compare results with new analyses of nuclear ITS sequences (119 accessions) from previous studies. Maximum likelihood and maximum parsimony analyses of cpDNA resolve well supported trees with most nodes having >95% bootstrap support. These trees strongly reject monophyly of Corymbia, its two subgenera (Corymbia and Blakella), most taxonomic sections (Abbreviatae, Maculatae, Naviculares, Septentrionales), and several species. ITS trees weakly indicate paraphyly of Corymbia (bootstrap support <50% for maximum likelihood, and 71% for parsimony), but are highly incongruent with the cpDNA analyses, in that they support monophyly of both subgenera and some taxonomic sections of Corymbia. The striking incongruence between cpDNA trees and both morphological taxonomy and ITS trees is attributed largely to chloroplast introgression between taxa, because of geographic sharing of chloroplast clades across taxonomic groups. Such introgression has been widely inferred in studies of the related genus Eucalyptus. This is the first report of its likely prevalence in Corymbia and Angophora, but this is consistent with previous morphological inferences of hybridisation between species. Our findings (based on continent-wide sampling) highlight a need for more focussed studies to assess the extent of hybridisation and introgression in the evolutionary history of these genera, and that critical testing of the classification of Corymbia and Angophora requires additional sequence data from nuclear genomes.

Exploring the Least Studied Australian Eucalypt Genera: Corymbia and Angophora for Phytochemicals with Anticancer Activity against Pancreatic Malignancies.

While the pharmacological and toxicological properties of eucalypts are well known in indigenous Australian medicinal practice, investigations of the bioactivity of eucalypt extracts against high mortality diseases such as pancreatic cancer in Western medicine have to date been limited, particularly amongst the genera Corymbia and Angophora. Four Angophora and Corymbia species were evaluated for their phytochemical profile and efficacy against both primary and secondary pancreatic cancer cell lines. The aqueous leaf extract of Angophora hispida exhibited statistically higher total phenolic content (107.85±1.46mg of gallic acid equiv. per g) and total flavonoid content (57.96±1.93mg rutin equiv. per g) and antioxidant capacity compared to the other tested eucalypts (P<0.05). Both A.hispida and A.floribunda aqueous extracts showed statistically similar saponin contents. Angophora floribunda extract exerted significantly greater cell growth inhibition of 77.91±4.93% followed by A.hispida with 62.04±7.47% (P<0.05) at 100μg/ml in MIA PaCa-2 cells with IC50 values of 75.58 and 87.28μg/ml, respectively. More studies are required to isolate and identify the bioactive compounds from these two Angophora species and to determine their mode of action against pancreatic malignancies.

Field Guide to the Cultivated Eucalypts (Myrtaceae) and How to Identify Them1

This paper provides identification keys that are based entirely on morphological features to commonly and widely cultivated eucalypts, encompassing Eucalyptus L'Hér., Angophora Cav., and Corymbia K. D. Hill & L. A. S. Johnson in the Myrtaceae Juss. The key includes 173 taxa: one species of Angophora, nine species of Corymbia, and 163 species of Eucalyptus. Evidence for cultivation was determined by accounts in the literature, herbaria, personal communications, and observations of living trees in cultivation in Europe, North America, Africa, and Australia. The locations, prevalence of cultivation, and naturalization of several eucalypt species are discussed.

Nematodes from galls on Myrtaceae. V. Fergusobia from large multilocular shoot bud galls from Angophora and Eucalyptus in Australia, with descriptions of six new species.

Six new species of Fergusobia, from large multilocular shoot bud galls on two species of Angophora and four species of Eucalyptus from both subgenera Eucalyptus and Symphyomyrtus, are described. Fergusobia cosmophyllae Davies n. sp. is characterized by the combination of a C-shaped parthenogenetic female with a short arcuate conoid tail, a broad (small a ratio) arcuate infective female with an hemispherical tail tip, and an arcuate to J-shaped male with broad, angular spicules and short bursa. Fergusobia delegatensae Davies n. sp. has an open C-shaped parthenogenetic female with a broadly conoid tail, an infective female of variable shape with an hemispherical tail tip, and a male of open C-shape with a crenate bursa that arises 40-70% along the length of the body from the tail tip and terminates just anterior to the cloaca. Fergusobia diversifoliae Davies n. sp. has a C-shaped parthenogenetic female with a conoid tail, an arcuate infective female with a hemispherical tail tip, and an arcuate, C- or J-shaped male with angular spicule and a long peloderan bursa. Fergusobia floribundae Davies n. sp. has a C-shaped parthenogenetic female with a narrow, arcuate, conoid tail, an arcuate infective female with a hemispherical tail tip, and an arcuate or J-shaped male with an angular spicule and a short to mid-body length peloderan bursa. Fergusobia minimus Lisnawita n. sp. has a C-shaped parthenogenetic female with a conoid tail, an arcuate to open C-shaped infective female with a hemispherical tail tip, and an arcuate to open C-shaped male with an angular spicule and a peloderan bursa arising at about 10-30% of body length. Fergusobia pimpamensis Davies n. sp. has an open C to C-shaped parthenogenetic female with a narrow conoid tail, an arcuate to open C-shaped infective female with a hemispherical tail tip, and an arcuate to C-shaped male with an arcuate spicule and a long, crenate, peloderan bursa. An inventory of all known Fergusobia/Fergusonina associations from terminal shoot bud galls is presented. The larval shield morphology of the associated mutualistic Fergusonina species is discussed where known. Analyses of DNA sequences of D2/D3 and COI suggested that the six new species are distributed between three clades of Fergusobia.

Variability in aggressiveness of Quambalaria pitereka isolates

Quambalaria shoot blight, caused by the fungal pathogen Quambalaria pitereka, is a serious disease of eucalypt plantations in Australia. The aggressiveness of four Q. pitereka isolates was compared on a range of host genera, species, provenances and clones. Isolates differed substantially in their aggressiveness, with two consistently showing higher levels of aggressiveness based on incidence and severity of disease and lesion size. Isolates derived from Corymbia citriodora subsp. variegata (Ccv) and C. torelliana were shown to have a relatively restricted host range, with lesions but no sporulation found on Eucalyptus species, Angophora species other than A. costata and Corymbia species other than Ccv, the host of origin. The level of aggressiveness toward the different provenances of spotted gum and C. torelliana varied between isolates and there was evidence of some isolate × host interaction within provenances of Ccv. The two methods of inoculation used in this study, spray and spot inoculation, gave similar results. However, the fact that the spot inoculation method was labour-intensive was a disadvantage limiting the numbers of isolates and hosts that can be tested.

New species of Mycosphaerella from Myrtaceae in plantations and native forests in eastern Australia

The majority of Mycosphaerella species from eucalypts (Eucalyptus, Corymbia and Angophora) in Australia have been recorded only from trees growing in plantations. This illustrates a bias in research in the past two decades toward commercial enterprise, and it emphasises a lack of understanding of the occurrence of these important fungi under natural conditions. Surveys of foliar fungi in native forests in eastern Australia, as well as adjacent plantations, thus have been initiated in recent years. In this study we describe four new species of Mycosphaerella from Eucalyptus spp. as well as other Myrtaceae. Mycosphaerella tumulosa sp. nov. (anamorph: Pseudocercospora sp.) was found on more than seven species of Eucalyptus and Corymbia in native forests and plantations in northeastern New South Wales and southeastern Queensland and appears to be relatively common, although not damaging to these trees. Mycosphaerella multiseptata sp. nov. was recorded from several locations on species of Angophora in native forests and amenity plantings. Mycosphaerella pseudovespa sp. nov. was found in one location in native forest on E. biturbinata. The first species of Mycosphaerella to be described from Syncarpia, M. syncarpiae sp. nov., was found in native forests in numerous locations from Sydney through to northeastern New South Wales and appears to be relatively common.

New species of Mycosphaerella from Myrtaceae in plantations and native forests in eastern Australia

The majority of Mycosphaerella species from eucalypts (Eucalyptus, Corymbia and Angophora) in Australia have been recorded only from trees growing in plantations. This illustrates a bias in research in the past two decades toward commercial enterprise, and it emphasises a lack of understanding of the occurrence of these important fungi under natural conditions. Surveys of foliar fungi in native forests in eastern Australia, as well as adjacent plantations, thus have been initiated in recent years. In this study we describe four new species of Mycosphaerella from Eucalyptus spp. as well as other Myrtaceae. Mycosphaerella tumulosa sp. nov. (anamorph: Pseudocercospora sp.) was found on more than seven species of Eucalyptus and Corymbia in native forests and plantations in northeastern New South Wales and southeastern Queensland and appears to be relatively common, although not damaging to these trees. Mycosphaerella multiseptata sp. nov. was recorded from several locations on species of Angophora in native forests and amenity plantings. Mycosphaerella pseudovespa sp. nov. was found in one location in native forest on E. biturbinata. The first species of Mycosphaerella to be described from Syncarpia, M. syncarpiae sp. nov., was found in native forests in numerous locations from Sydney through to northeastern New South Wales and appears to be relatively common.

Epicormic strand structure in Angophora, Eucalyptus and Lophostemon (Myrtaceae) – implications for fire resistance and recovery

Summary Epicormic bud producing structures in the eucalypts, a large group of woody plants of considerable ecological, horticultural and silvicultural importance, are described here. The outer portion of epicormic strands excised from the bark of large diameter stems of 18 Eucalyptus species, two Angophora species and Lophostemon confertus was examined anatomically in semithin sections. In the inner bark each eucalypt strand usually possessed 5–12 radially orientated strips of tissue of meristematic appearance. The meristem strips were c. 30–50 µm high, 70–110 µm wide and 2000–10 000 µm long, with a lacuna above the meristem surface. Few buds or bud primordia were associated with the strands and the strands appeared to have a reduced regenerative potential in the outer bark. In most angiosperm trees dormant epicormic buds are present in the outer bark, a position where they could be killed by fire. By contrast, in eucalypts the greatest epicormic bud initiation potential is at the level of the vascular cambium, which is protected by the maximum bark thickness. This might explain the pronounced ability of eucalypts to produce bole and branch epicormic shoots after moderate to intense fire.

English

Hill, K.D. (National Herbarium of New South Wales, Royal Botanic Gardens, Mrs Macquaries Road, Sydney, NSW 2000, Australia) 1996. New species in Angophora and Eucalyptus (Myrtaceae) from New South Wales. Telopea 7(2): 97–109. Two new species of Angophora (A. inopina and A. exul) and three new species of Eucalyptus (E. aenea, E. dissita and E. fracta) from New South Wales are described and illustrated. Distribution maps are provided, and conservation status is discussed. All species are regarded as rare or threatened.

Phylogeny of Eucalyptus and Angophora Based on 5S rDNA Spacer Sequence Data

Sequences of the 5S rDNA repeat have been determined from four outgroup taxa (Arillastrum group), 2 Angophora species, and 19 Eucalyptus species (including representatives from all informal subgenera). Alignment shows that, as in other plants, the tandemly repeated 5S rRNA genes are highly conserved while the noncoding intergenic spacers are variable. A 50-base pair (bp) repeating element, which has undergone duplication and modification in certain taxa, is identifiable within the spacer and accounts for much of the variability. There were several other multiresidue deletion/insertion events in the spacers that define major clades. Based on the indel events and modifications of the 50-bp element it is apparent that the spacer from bloodwood (informal subgenera Blakella and Corymbia) species of Eucalyptus is more similar to that of Angophora than to non bloodwood species of Eucalyptus. Parsimony analysis showed Eucalyptus to be paraphyletic, with the bloodwoods being more closely related to Angophora than to the rest of Eucalyptus. This finding supports taxonomic revision of Eucalyptus.

Development of the Stomatal Complexes During Ontogeny in Eucalyptus and Angophora (Myrtaceae)

The mode of stomatal development is studied in cotyledons, seedling and adult leaves of species of eucalypts and three species of Angophora. In the cotyledons of all species examined the early stomatal initials are unilabrate or dolabrate. The stomatal initials in seedling leaves of species of the Corymbosae and Clavigerae are anisocytic. In the 4th seedling leaf in species of a group we have previously called Monocalyptus the stomatal initials are also anisocytic. All other eucalypts retain the early cotyledonary mode of origin of stomata throughout life. These two modes of origin, whether anisocytic or by unilabrate and dolabrate initials, are set in all eucalypts from the 4th seedling leaf onward. Secondary characteristics of the adult stomata, e.g. number of subsidiary cells, are more complex than those of the seedling leaves; rarely, the relatively simple pattern of the seedling leaves may persist in the adult leaves of a given species. In species in which the initials in adult leaves are unilabrate or dolabrate, groups of stomata may share one or more subsidiary cells or be juxtaposed without an intervening subsidiary cell. The sister cell(s) of the guard mother cell may precociously develop a thicker cuticle than ordinary epidermal cells, and this may be apparent at maturity. The abaxial stomata of the cotyledons (but not of seedling or adult leaves) are regularly aligned parallel to the main venation. The existence of three main types of origin of stomata characteristic of three large non-interbreeding groups of eucalypts is of interest in the taxonomy of the genus.

Stigma and Style Morphology in Relation to Taxonomy and Breeding Systems in Eucalyptus and Angophora (Myrtaceae)

The stigma and style of 94 species of Eucalyptus and two species of Angophora were studied by scanning electron microscopy and/or light microscopy. All species had papillate stigmas and a stylar canal of varying length. Angophora species had mop-like stigmas with long papillae that were very similar in appearance to those of the red bloodwood group of the Corymbia, e.g. E. gummifera. The spotted gum group of the Corymbia had mop-like stigmas with short papillae and the yellow bloodwoods had tapered stigmas. The latter group was also charaderised by an extremely thick cuticle on the outer surface of the style, over 100 �m in thickness in E. watsoniana. All species in Blakella had tapered stigmas with a lobed surface and relatively few short papillae. The stylar canal had no cuticle in E. papuana. Eudesmia is a variable subgenus with E. erythrocorys unusual in having long multicellular papillae. Most Symphyomyrtus species had blunt or pinhead-shaped lobed stigmas with a heavily cutinised stylar canal. E. deglupta and E. microcorys did not conform to this pattern and had mop-shaped stigmas with long papillae. Monocalyptus species had blunt stigmas with few papillae and hollow styles and appeared to form a cohesive group. On the basis of stigma and style morphology Angophora is more similar to Corymbia than to Blakella. E. deglupta and E. microcorys are distinct from other Symphyomyrtus species studied. E. trachyphloia and E. jacobsiana are more similar to E. gummifera than to E. watsoniana or other yellow bloodwoods.

Ecological Differentiation Between Species of Scribbly Gums [Eucalyptus Informal Subseries Haemastominae (MATK) Prior &amp;amp; Johnson] and Angophora in Seedling Responsiveness to Mineral Nutrients

When four species of scribbly gums (Eucalyptus subseries Haemastominae) and four species of Angophora, together with Eucalyptus pilularis, were grown in a range of nutrient levels from distilled water to full Hoagland's nutrient solution, the two groups reacted differently, reflecting their contrasting distributions in relation to soil fertility. Their mean relative growth rates were similar, but the magnitude of the response to increasing nutrient availability varied among the angophoras although it was very similar for all the scribblies. The degree of response of the angophoras was correlated with the fertility of their natural soils: A. floribunda, coming from the most fertile soils, showed the greatest response in mean relative growth rate to increasing nutrient supply. Specific leaf areas did not vary among nutrient levels but, as with mean relative growth rates, the angophoras showed a correlation between the fertility of their natural soils and the specific leaf area: A. hispida, from the least fertile soils, developed the thickest leaves. The angophoras differed from each other in leaf area ratio whereas the scribblies did not. This characteristic was influenced by nutrient availability: the angophoras growing at the higher levels of nutrient supply developed greater leaf areas ratios. There was little difference among the four scribbly gum species in their response to nutrients. They all occur on infertile soils and showed little response to increased nutrient supply.

The occurrence of 5-Hydroxy-7,4'-dimethoxy-6-methylflavone in Eucalyptus waxes

5-Hydroxy-7,4'-dimethoxy-6-methylflavone (II) has been shown to occur with 5-hydroxy-7,4'-dimethoxy-6,8-dimethylflavone (I) in the leaf waxes of Eucalyptus torelliana F. Muell. and E. urnigera Hook. The nuclear magnetic resonance spectra of (II) and related compounds have been measured, and it is shown that N.M.R. spectroscopy is useful in determining the relative proportions of the two components at equilibrium in a Wessely-Moser rearrangement. Leaf waxes from several Angophora species also contain compound (I).

On the elastic substance occurring on the shoots and young leaves of Eucalyptus corymbosa and some species of Angophora

On the elastic substance occurring on the shoots and young leaves of Eucalyptus corymbosa and some species of Angophora