bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphotypic Differentiation in the South-Western Australian Restiad Lyginia barbata R.Br (Restionaceae)
Authors: Bell TL , Pate JS
Published: December 2005

Study of Lyginia barbata across its distribution range in south-western Australia identified five distinctive morphotypes, viz. a tall-culmed, densely tufted fire-sensitive obligate seeder (S morphotype), a tall densely tufted fire-resistant resprouter (R1), a short flexuose-culmed, tufted resprouter (R2), a weakly clonal, semi-tufted resprouter (R3) and a short-culmed, widely spreading clonal form (R4). There was little variation within a morphotype between habitat locations and no evidence of intergrading of cohabiting morphotypes. Morphotype-specific differences were observed in culm height, rhizome morphology, culm density and spikelet morphology. Differences in reproductive biology related to the time of first reproduction in juvenile recruits, spikelet number per male and female culm, ovule number per female culm and seed : ovule ratio. Differences of a physiological nature were observed in seedling growth rates and proportional biomass (dry matter) allocations to culms, rhizomes, spikelets and seeds. Comparative quantitative scorings of the above features according to concepts of r- and K-selection rated the S form strongly r-selected, the R4 form equally strongly K-selected and the other forms (R1, R2 and R3) intermediate and with the R1 form possibly more r-selected than the others. It is suggested that the data provide a basis on which future taxonomic decisions regarding the taxon might be made.
Germination and Establishment of Themeda triandra (Kangaroo Grass) as Affected by Soil and Seed Characteristics
Authors: Sindel BM , Davidson SJ , Kilby MJ , Groves RH
Published: December 2005

The seed supply of Themeda triandra, syn. T. australis (kangaroo grass), for revegetation purposes may always be limited given the biological constraints on its production. It is important, therefore, that available seed be used efficiently by maximising germination and establishment. In two glasshouse experiments, we investigated the effects of various soil and seed factors and their interactions on germination and establishment of seeds sown on the soil surface and at depth. Maximum germination was achieved by either de-awning seeds and burying them manually at 1 cm depth or by sowing awned seeds on the soil surface in the vicinity of cracks or stones which allowed up to 96% of the seeds to bury themselves by natural means. Diurnal fluctuations in relative humidity of only 30% caused the 4-6 cm long geniculate awns to twist hygroscopically, thereby propelling the seeds along the soil surface and increasing their chances of becoming buried in favourable or 'safe' microsites for germination. A bitumen-coated straw mulch improved germination of de-awned seeds by maintaining high moisture content in the top 2 cm of soil, but inhibited the movement of awned seeds along the soil surface and their entry into safe microsites for germination. The data are discussed in terms of maximising germination and seedling establishment of Themeda, determining the most appropriate seed harvesting and cleaning methods, and selecting sowing methods which are most likely to be effective.
Seed Germination Physiology of Eucalyptus delegatensis R. T. Baker in Tasmania
Authors: Battaglia M
Published: December 2005

The seed germination response of seedlots from five geographically disparate provenances of Eucalyptus delegatensis to temperature, stratification, soil matric potential, relative humidity and interrupted imbibition was examined. The species was found to have a distinct temperature optimum of between 15 and 20°C, and a minimum temperature for germination of approximately 2°C. Short periods of exposure to high temperatures did not substantially affect germination performance. Stratification greatly increased the range of temperatures over which a high proportion of the seed germinated. Increases in the rate of germination with stratification are related to accrued thermal time during stratification. Pre-imbibing seeds at water potentials down to -2 MPa increased the rate of germination; however, no advantage was found after pre-imibibing at -3 MPa. This increased germination rate was associated with a shortening of the time to commencement of germination and more synchronous germination. Germination rate and germination capacity were impeded by soil matric potentials below -0.01 MPa, and germination was totally inhibited by soil matric potentials below -0.5 MPa. Soil matric potential and temperature interacted in their effects on germination capacity, and seeds germinating at near optimum temperatures were less sensitive to soil moisture stress. Seeds survived dehydration within 60 h of the commencement of imbibition, but were increasingly affected by dehydration thereafter. The rate of imbibition was influenced by the ambient temperature and solution water potential. At modest levels of water stress, imbibition was not impeded and the reduction in germination capacity was probably due to the inhibition of growth related processes. Differences in germination response were detected between the seedlots and these could be related to the geographic origin of the seedlots.
Ontogenetic Variation in Frost Resistance of Eucalyptus delegatensis R. T. Baker
Authors: Battaglia M , Reid JB
Published: December 2005

The frost resistance of Eucalyptus delegatensis is shown to vary with seedling age over the first
6 months of development. Much of this variation is a result of the differing sensitivity of leaves
originating from different leaf nodes, although older leaves from the same node may be more frost
resistant than recently expanded leaves. Newly emergent seedlings appear to be the most susceptible
stage of the tree's lifecycle to death by frost.
Seasonal Production of Hypogeal Fungal Sporocarps in a Mixed-Species Eucalypt Forest Stand in South-Eastern Australia
Authors: Claridge AW , Robinson AP , Tanton MT , Cunningham RB
Published: December 2005

The seasonal production of hypogeal fungal sporoearps was monitored over an 18 month period in a catchment of mixed-species euealypt forest in East Gippsland, Vietoria. During the study, sporocarps of one Ascomycete and 25 Basidiomycete species were collected from soil quadrats sampled sequentially around the bases of eucalypt trees- Sporocarps from these species varied in their dimensions and morphological characteristics. Productivity varied from 21 000 sporocarps ha-1 to 181 000 sporocarps ha-1 or 1.8 kg ha-1 to 8.3 kg ha-1 per month. The probability of occurrence of sporocarps was, on average, greater in midslope sites on a sheltered aspect than elsewhere within the catchment. The number of sporocarps produced varied over time, with a major peak in production occurring during May (late-autumn). This peak occurred mainly within gully sites, which supported on average a greater number of sporocarps than ridge or midslope sites, but a lesser weight of sporocarps. The distribution and productivity (probability of occurrence, number and weight) of sporocarps appeared to be associated with some environmental (soil) variables, but not the physical variables (host tree), that we measured. Sporocarps of some species fruited predominantly in ridge and slope habitats, some species fruited mainly in gullies, whereas others apparently showed no preference for fruiting in ridges, slopes and gullies. Thus, in forest catchments subject to land-management practices such as logging and fire, it may be important to retain undisturbed habitat throughout the topographic sequence to conserve a diversity of hypogeal species.
The Effect of Microsite Variation on Seed-Germination and Seedling Survival of Eucalyptus delegatensis
Authors: Battaglia M , Reid JB
Published: December 2005

The correlation between microsite and seedling numbers was determined in field sowings, and the impact of microsites on germination and seedling survival tested in artificial seedbeds in the glasshouse. Small scale variation in soil conditions, at the scale of tens of centimetres, markedly affected the germination and establishment of Eucalyptus delegatensis R.T.Baker seeds and seedlings. Under conditions of limiting soil moisture, microsites that afforded protection, and probably resulted in increased humidity, caused a marked increase in germination number and rate. The mean survival time was significantly higher on these protected microsites than on less protected microsites, or on microsites that restricted root penetration. The importance of this variability in microtopography was strongly influenced by season and the level of environmental stress, and was diminished as seedlings aged. Due to the different requirements for seed germination and seedling growth, a favourable microsite for germination was not necessarily a favourable site for seedling survival. A comparison of seed and seedling responses to water stress indicated that for E. delegatensis, at least, selection due to microsite differences at the time of germination may not have an impact on the developmental characteristics of the seedlings.
The Influence of CO2 Enrichment on Growth, Nutrient Content and Biomass Allocation of Maranthes corymbosa
Authors: Berryman CA , Eamus D , Duff GA
Published: December 2005

Seedlings of Maranthes corymbosa Blume, an evergreen tree of tropical Australia and Indonesia were grown for 32 weeks under conditions of ambient and elevated (700 μmol CO2 mol-1) CO2 in tropical northern Australia. Seedlings were exposed to ambient temperature, vapour pressure deficit and photon flux density fluctuations. Rates of germination and percentage germination were not affected by elevated CO2. Total plant biomass, height growth, total plant leaf area, numbers of leaves and branches and specific leaf weight were significantly increased by elevated CO2. Root:shoot ratio and foliar P, K, Mg, Mn and Ca levels were unaffected but foliar nitrogen levels were decreased by elevated CO2, Nutrient-use-efficiency was unaffected for phosphorus, magnesium, manganese, calcium and potassium but nitrogen-use-efficiency increased in response to elevated CO2.
Differences in the Stand Structure of Eucalyptus tetrodonta Forests Between Elcho Island and Gunn-Point, Northern Australia
Authors: Bowman DMJS , Panton WJ
Published: December 2005

Eucalyptus tetrodonta dominated open forests occur across the northern coast of the Northern Territory. They typically have a well developed grass understorey, scattered saplings, numerous woody sprouts (ramets) and a conspicuous absence of seedlings (genets). We compared a typical E. tetrodonta stand on Gunn Point with an atypical stand on Elcho Island; the forest on Elcho Island had less grass cover, greater canopy and litter cover, a deeper organic layer and higher densities of seedlings, woody sprouts and saplings than on Gunn Point. Gunn Point had a greater number of large E. tetrodonta trees that were more widely spaced than trees on Elcho Island. The cause of these differences remains unclear.
Mycelial Interactions and the Potential Use of Tuft Formation in Characterizing Rhizoctonia solani Isolates Infecting Cereals
Authors: Yang HA , Sivasithamparam K , Obrien PA
Published: December 2005

Field isolates of Rhizoctonia solani anastomosis group (AG) 8, the most important causal pathogen of cereal bare-patch disease, were paired with each other and with tester strains of other AGs on potato-dextrose agar amended with charcoal (PDCA) to investigate mycelial interactions. Pairings among AG 8 field isolates produced compatible interactions of either tuft or merging reactions. Tufts formed between all paired field isolates from different pectic zymogram groups (ZGs) within AG 8, but pairings between genetically identical isolates showed merging reactions. Pairings of AG 8 field isolates with the tester strains of the other AGs led to incompatible interactions varying from merging line to barrage reactions. As formation of a tuft indicates that the paired isolates are able to anastomose and to form viable heterokaryons, the testing of mycelial interaction types, highlighted by tuft formation, may be used as a rapid procedure to characterise field isolates of R. solani obtained from cereals.
Germination of Seeds From the Fruits of Thryptomene calycina (Myrtaceae)
Authors: Beardsell DV , Knox RB , Williams EG
Published: December 2005

Freshly fallen fruits of T. calycina contained seeds which were completely dormant; none germinated after 200 days at 20°C. Seeds excised with testas intact from fresh fruits were partially dormant; one-third germinated after 60 days. The dormancy of seeds in freshly fallen fruits was imposed jointly by the fruit and the seed. The major site of the dormancy was however the seed coat since tearing part of it away from seeds excised from fresh fruits resulted in rapid and complete germination. Fruits stored dry in a laboratory at 20°C for 90 days were partially dormant. Nicking the distal end of these fruits enhanced germination. Seeds excised from these laboratory stored fruits had 85 % germination, which indicated a reduction in the seed imposed dormancy. Germination of T. calycina was independent of light and, although the fruits contained large amounts of phenolic material this did not inhibit germination. Fruits weathered in the field for at least 2 years contained less viable seeds, presumably because of insect predation, but these all germinated within 50 days at 20°C. Brief washing of fruits in concentrated sulphuric acid increased germination. Germination was not enhanced by treatment with low concentrations of gibberellic acid in the presence or absence of cytokinin.
The Effect of Light Quality on the Germination of Eight Species From Sandy Habitats in Western Australia.
Authors: Bell DT
Published: December 2005

The impacts of darkness and a range of monochromatic light conditions on germination was documented for eight native and naturalized species growing in sandy habitats in Western Australia. Four lake-margin species, Juncus articulatus, J. microcephalus, J. pallidus and Isolepis prolifera, germinated under red (c. 520-640 nm) light, but remained dormant in the dark or when illuminated with far-red (720 nm) or blue (430-490 nm) light. Sunlight-stimulated germination could be beneficial to these very small seeded species, which may not have sufficient reserves for seedlings to establish following deep burial.
Oenothera stricta, a short-lived ruderal species, was also stimulated by red light, a response possibly related to germination following disturbance of overlying vegetation. Trachyandra divaricata, a dune inhabiting species, was inhibited by red light. Inhibition by the wavelengths of light dominant in full sunlight was thought to be a response beneficial to species of blowing sand habitats where germination on the dry surface could prove detrimental. Oenothera drummorndii , also a species of coastal dunes was
inhibited under high energy light (430-490 nm) but showed no percentage gemination differences in light of wavelengths between 520 and 720 nm and under dark conditions. Asphodelus fistulosus, a species of similar life-fonn characteristics to Trachyarndra divaricata, showed no effect on germination percentage of varying light quality.
Selection of Grasses With Different Carbon Assimilation Pathways Under Different Sheep Stocking Pressures.
Authors: Rogers RW
Published: December 2005

The path of carbon assimilation was noted for 30 common grasses from unfertilized sheep pastures of the Northern Tablelands of New South Wales. These grasses were then grouped according to their susceptibility to stocking pressure and the frequency and relative frequency of 16 of these related to apparent intensity of stocking about a sheep camp. C3 grass frequency was independent of stocking pressure, but under heavy stocking introduced C3 species replaced native C3 species. C4 NADME species showed an increase in occurrence under high stocking rates, whereas C4 NADPME species showed a decrease in occurrence under high stocking intensity. It is suggested that response to grazing may have been a factor in the evolution of different pathways of carbon assimilation.
Breeding System and Reproductive Success of Thryptomene calycina (Myrtaceae)
Authors: Beardsell DV , Knox RB , Williams EG
Published: December 2005

Thryptomene calycina (Lindl.) Stapf is a small bush with a long flowering period in winter. Hundreds of small flowers open at one time. Its breeding system is highly self-incompatible, with an index of Self-Incompatibility of 0 - 0.1. The site of arrest of self-incompatible tubes is near the micropyle. In wild populations the natural seed set varies between 9 and 13%. Pollination is not a factor limiting seed set in these flowers since every stigma examined from wild populations carried some germinated pollen grains. The low level of seed production is because most pollinations are probably ineffective selfs which occur when pollen exudes from pores in the anthers directly over the stigma; air currents and rain splashing probably accentuate the effect. Self-pollination is facilitated by the long period of stigma receptivity which occurs for 12 days commencing 2 days after anthesis. Each flower contains approximately 60 000 pollen grains that are viable for up to 15 days. The pollen-ovule ratio is high, up to 32 000. Most pollen is shed 3 days after anthesis, but this depends on temperature, relative humidity and probably the water potential of flowers. The flowers are visited by few flying insects during most of the flowering season. In warm weather near the end of flowering a wide range of insects visit the flowers. Although the visitors are mostly small flies these are ineffective pollinators. The main potential pollinators are medium sized flies and bees.
Apparent Mutualism Between Verticordia nitens and V-Aurea (Myrtaceae) and Their Oil-Ingesting Bee Pollinators (Hymenoptera, Colletidae)
Authors: Houston TF , Lamont BB , Radford S , Errington SG
Published: December 2005

The prominently-displayed flowers of Verticordia nitens and V. aurea are unattractive to most insect pollinators and yet apparently serve as the sole source of pollen and nectar for two species of solitary bee. Euryglossa (Euhesma) morrisoni forages exclusively on V. nitens and E. (E.) aureophila forages exclusively on V. aurea. These bees carry much pollen on their bodies and appear solely responsible for seed set of 9-31% of ovules, with negligible seed set by V. nitens in the absence of E. morrisoni. Each anther of both Verticordia species releases pollen in copious amounts of oil (pollenkitt) beneath a hood-like appendage which terminates in a spout. Female bees ingest the pollen-oil mixture by touching the appendages with their glossae, and nectar by lapping the floor of the hypanthium. Most of the oils are isopentyl esters of the fatty acids, palmitic, stearic, arachidic (the major component of V. nitens) and behenic (the major component of V. aurea). These oils, as well as significant amounts of glucose, fructose and proline, are also present in the crop of E. morrisoni. The ability ofE. morrisoni and E. aureophila to remove and utilise pollen, oil and nectar from the flowers, their effectiveness as sole pollinators, and flower colour mimicry by E. morrisoni, together suggest an obligate mutualism between these bees and their Verticordia hosts.
Selection Against Homozygotes and Resource Allocation in the Mating System of Eucalyptus camaldulensis Dehnh
Authors: James SH , Kennington WJ
Published: December 2005

Allozyme genotypes of seed progeny were determined for an essentially self-pollinating individual of E. camaldulensis heterozygous at the LAP and GPI-2 loci. The seed exhibited a normal 1:1 allelic recovery, and an excess of heterozygotes relative to Mendelian expectations that was significant at the GPI-2 locus (χ2[1] = 58.0, P<0.001). GPI-2 allozyme genotypes were also determined for the seed produced by an open-pollinated E. camaldulensis growing in a mixed clonal plantation. Most of the seed produced by this plant exhibited non-maternal alleles and was the result of cross-pollination. We conclude that post-zygotic seed selection was selectively eliminating genetic homozygotes from the selfed progeny and amplifying the frequency of cross-pollination products in the open-pollinated tree. We also found that the level of selection within fruits of the self pollinated tree was dependent upon the number of seeds and the number of ovules per capsule (P=0.019, r2=0.63 and P=0.008, r2=0.79 respectively using pooled classed data); selection intensities were found to be greater in fruits containing lower numbers of seeds or ovules. This may reflect the level of resources allocated to the fruit by a hormonally controlled positive feedback system. Incorporating the notions of heterosis or selection against recessive homozygotes and resource allocation allowed the presentation of alternative explanations for the low estimates of î found in eucalyptus producing low numbers of flowers and for the temporal heterogeneity in outcrossing rates reported in E. delegatensis.
Phenotypic, Genetic and Ecological Variation in the Eucalyptus saligna̵1E. botryoides Complex
Authors: Passioura JA , Ash JE
Published: December 2005

Analysis of variation within the E. saligna-E. botryoides complex indicates a continuum of morphological variation, particularly in bud, fruit and bark characters, between the taxa. The continuum occurs between populations north of Sydney (which had always been recognised as E. saligna), and populations restricted to the coastal fringe (which had always been recognised as E. botryoides). There is a suggestion of a latitudinal cline in morphology of the intermediate populations, although it is complex, and shows significant local variation. Analysis of allozyme data indicates that most of the genetic variation within the complex is contained within rather than between populations, and that genetic distances between populations are more typical of within-species rather than between-species differences. The lack of allozyme divergence is attributed to either relatively rapid and recent differentiation or to extensive introgression following secondary contact of the taxa. Analysis of environmental variables reveals two discriminating factors in relation to the current distributions of populations within the complex. Firstly, the morphological gradient appears to follow an underlying temperature gradient, and secondly, E. botryoides occupies a separate niche associated with the distinct coastal environment on which it occurs. These key environmental parameters may have been important in the evolution of the complex along axes of latitude or temperature, and coastal versus inland habitat. Additionally, changes in distribution of the taxa as a result of climatic changes associated with glacial-interglacial cycles may also have played an important role in the formation of the complex.
Secondary Pollen Presentation in Angiosperms and Its Biological Significance
Authors: Howell GJ , Slater AT , Knox RB
Published: December 2005

Secondary pollen presentation is the developmental relocation of pollen from the anthers onto another
floral organ which then functions as the pollen presenting organ for pollination. Nine different types
have been identified in sixteen angiosperm families according to which organ is used for presentation,
whether the pollen is exposed or concealed within a structure and how pollen is loaded onto the
presenting surface: (1) Enveloping bloom presenters (Araceae); (2) Perianth presenters with exposed
pollen presentation (Epacridaceae); (3) Androecial presenters (Santalaceae); (4) Terminal stylar
presenters with passive pollen placement and concealed stigmas (Rubiaceae and Proteaceae); (5)
Terminal stylar presenters with passive pollen placement and sub-terminal stigmas (Marantaceae and
Polygalaceae); (6) Terminal stylar presenters with active pollen placement (Asteraceae, Calyceraceae
and Lobeliaceae); (7) Sub-terminal stylar presenters (Campanulaceae, Cannaceae, Fabaceae and
Myrtaceae); (8) Exposed stigmatic presenters (Rubiaceae); (9) Indusial stigmatic presenters
(Goodeniaceae and Brunoniaceae). Secondary pollen presentation occurs in three monocotyledon and
thirteen dicotyledon families. The presentation types appear to have been independently derived
indicating that secondary pollen presentation is a character with a selective advantage.
In all but the enveloping bloom type of secondary pollen presentation, developmental relocation of
pollen requires simultaneous, introrse anther dehiscence and a close association of the presenting organ
to the anthers prior to anthesis.
The various secondary pollen presentation systems may be modified to promote xenogamy or
autogamy and this can even change during anthesis. Most plants which have secondary pollen
presentation, display reduced herkogamy within the flower to facilitate pollination. Increased risk of
self-pollination due to this may be overcome through dichogamy, herkogamy within inflorescences, dry
stigmas, self-incompatibility systems and passive or active control over pollinator behaviour. Enhanced
male function of the flowers of secondary pollen presenting plants is also evident through extension of
the male phase by the protection, controlled release and precise placement and receipt of pollen. Plants
displaying secondary pollen presentation are almost always protandrous.
Pollen Presenter and Pollen Morphology of Banksia L.f. (Proteaceae)
Authors: Sedgley M , Sierp M , Wallwork MA , Fuss AM , Thiele K
Published: December 2005

The morphology of the pollen presenter and pollen was studied in 79 taxa of Banksia using scanning electron microscopy. There were three major types of pollen presenter. Elongated and cylindrical structures were characteristic of the series Banksia, Crocinae, Tetragonae, Coccineae and some species of the Cyrtostylis and Abietinae. Short and cylindrical pollen presenters were found in the series Salicinae, Quercinae, Prostratae and some species of the Cyrtostylis. Short and ovoid pollen presenters were found in the series Grandes and Dryandroideae, and in the species B. brownii and B. ericifolia of the Spicigerae and B. pulchella of the Abietinae. The pollen-receptive stigma cells of all taxa were enclosed within a groove, which in the majority of species was obliquely terminal and longitudinal. Subterminal grooves, all of which were longitudinal, except that of B. speciosa which was located laterally, were observed in a few species. Pollen of all taxa had two germination pores, at opposite ends of a cylindrical, ovoid or crescent-shaped grain. There was a higher level of between species and between group consistency in pollen grain than in pollen presenter structure. The results have implications for both the interspecific fertility relationships and taxonomy of the genus.
Pistil Structure of Banksia menziesii R.Br. (Proteaceae) in Relation to Fertility
Authors: Clifford SC , Sedgley M
Published: December 2005

The morphology and histochemistry of the pistil of Banksia menziesii were studied to determine whether the observed low fertility of the species has a structural basis. The distal portion of the style, the pollen presenter, was distinct in both external and internal morphology from the remainder of the style. It was an elongated structure with eight longitudinal ridges, a swollen base, and with pollen-receptive stigma cells enclosed within a groove located at its tip. The stigma was wet papillate, and was covered with a lipidic secretion overlying polysaccharide-rich mucilage. Below the groove, the solid transmitting tract comprised a few thick-walled cells surrounded by numerous transfer cells, and vascular bundles associated with sclerenchyma. The style immediately below the pollen presenter was constricted, and the transfer cells ended in this region. The upper stylar cortex consisted largely of sclerenchyma, and the transmitting tract narrowed towards the base, comprising only 10.9 ± 0.3 cells at the junction with the ovary. The ovary contained two ovules, both of which were functional at anthesis, although the upper ovule developed more quickly than the lower. The inflorescence consisted of over 700 flowers, of which 2.5 ± 0.2% had short styles and pollen presenters with exposed stigma papillae. Apart from this, there was no variation in pistil structure which would explain the observed low fertility.
Reproductive Biology and Floral Phenologies of the Sympatric Species Leptospermum myrsinoides and L. continentale (Myrtaceae)
Authors: Obrien SP , Calder DM
Published: December 2005

The reproductive biology and floral phenologies of co-occurring Leptospermum myrsinoides and L. continentale were investigated. Both species have similar floral structure and both are protandrous. Anther dehiscence is staggered over approximately 6 days and pollen viability remains high for at least 3 days. The styles of both species are short at anthesis but extend during the next 6 days to approximately the same height as the anthers. The stigmas of these species do not achieve maximum receptivity until at least 4 days after anthesis. Both species are self-compatible. At the three sites studied, L. myrsinoides and L. continentale have separate flowering times with L. myrsinoides always flowering first. Within populations of each species, plants reached first flower and peak flower in the same order in 1989 and 1990, implying genetic control over flowering time. It is suggested that protandry in these species enhances the likelihood of outcrossing and the staggered release of pollen coupled with the degree of overlap within flowering populations increases the number of potential mates available to each flower.
Pollination in Australian Orchids: a Critical-Assessment of the Literature 1882-1992
Authors: Adams PB , Lawson SD
Published: December 2005

A century of pollination studies of Australian orchids is reviewed. Descriptions of pollination events and conclusions about pollination status are inadequate in many reports. In this review criteria for establishing 'confirmed', 'probable' and 'suggested' pollinator status are defined and recommended. When applied to 153 published pollination reports there are 24 terrestrial species with 'confirmed' pollinators and a further 47 species with 'probable' pollinators. The major syndromes confirmed are wasp pollination by pseudocopulation (15 species) and the bee pollination syndrome of food mimicry (5 species). Nectar and pollen reward systems operate in a small number of species. Eleven epiphytic species have 'confirmed' pollinators, and four have 'probable' pollinators. Thirteen of the fourteen confirmed reports of epiphyte pollination describe social or solitary bees, mainly of the genus Trigona, apparently attracted by floral display and intense fragrance, which may constitute a chemical reward system. Dendrobium is the main epiphytic genus with confirmed pollinators.
Comparative Reproductive Biology of Two Sun-Orchids; the Vulnerable Thelymitra circumsepta and the Widespread T. ixioides (Orchidaceae)
Authors: Sydes MA , Calder DM
Published: December 2005

Two morphologically similar Sun-orchid species, Thelymitra ixioides Sw. and T. circumsepta Fitzg.
were studied with respect to their reproductive ecology. Breeding systems were found to contrast
strongly. In this study the widespread, T. ixioides is insect pollinated and encourages xenogarny by
relying on native Lasioglossum and Exoneura bees for pollination. In contrast, the vulnerable and
restricted T. circumsepta was found to autopollinate. These two species differ in floral display and
reproductive efficiency. These breeding systems are discussed in relation to the life histories of the two
species.
The Reproductive Ecology of Canavalia rosea (Fabaceae) on Anak Krakatau, Indonesia
Authors: Gross CL
Published: December 2005

Pioneer plant species are expected to have higher fruit-to-flower ratios than plants found in more established habitats. This was not found to be the case with Canavalia rosea on Anak Krakatau, Indonesia. Canavalia rosea is a pantropical pioneer plant species of beach habitats. On Anak Krakatau fruit-set in C. rosea in July 1992 ranged between 10 and 19% and a study of pollination and resource levels was undertaken to determine the cause of low fruit-to-flower ratios. An examination of flowering and fruiting phenology, breeding system and floral visitors revealed that low fruit-set in the population could not be explained by either a lack of pollinators or low levels of deposited pollen. Experimental removal of pods resulted in a near five-fold increase in fruit-set on subsequent flowers on treated plants compared with natural levels, indicating that fruit-set was resource limited. Low fruit-to-flower ratios do not detract from the colonising success of this species however, because individual plants flower prolifically year-round ensuring a constant production of propagules.
Pollen Storage and Breeding System in Relation to Controlled Pollination of Four Species of Acacia (Leguminosae: Mimosoideae)
Authors: Sedgley M , Harbard J
Published: December 2005

Pollen of A. auriculiformis, A. iteaphylla, A. karroo and A. mangium was stored at 25, 5, -18 or -196°C for up to 3 years, and its viability tested by pollen staining, in vivo pollen tube growth or pod set 1 month after hand pollination. The effectiveness of staining methods using 2,3,5-triphenyltetrazolium chloride (TTC), 5-bromo-4-chloro-3-indole- β -galactoside (X-Gal) and fluorescein diacetate (FDA) to predict pollen viability was investigated. All of the staining methods gave variable results, but the TTC and X-Gal tests were particularly unreliable. FDA staining of pollen gave the best indication of its ability to germinate on the stigma and penetrate ovules. Pollen stored for up to three days at 25°C retained the ability to penetrate ovules following hand pollination, and of that stored for three years at 5°C, 19% of the grains fluoresced with FDA. Pollen stored at -18°C for 1 year retained the ability to penetrate ovules and produce pod set, and of that stored for 3 years, 23% of the grains fluoresced with FDA. Pollen stored at -196°C for one year retained the ability to penetrate ovules and produce pod set, but thawing and refreezing of the pollen reduced viability to zero. It was concluded that the most successful and convenient method of pollen storage was vaccuum drying followed by storage at -18°C. The Australian species of Acacia investigated (A. iteaphylla, A. auriculiformis and A. mangium) had protogynous flowers, with stigma receptivity preceding anther dehiscence, such that flowers could be reliably hand pollinated. The African species A. karroo had protandrous flowers, with stigmas unreceptive at anthesis, but receptive at 5 days after anther dehiscence. Deposition of self pollen on the stigma prior to attainment of receptivity rendered hand pollination of this species unreliable.
Reproductive-Biology of the Australian Species of the Genus Pandorea (Bignoniaceae)
Authors: James EA , Knox RB
Published: December 2005

We studied the reproductive biology of Australian species of Pandorea to facilitate a breeding program designed to develop elite cultivars for the horticultural industry. P. pandorana is protogynous whereas anther dehiscence and stigma receptivity occur at the same time in P. jasminoides and P. baileyana. The stigmas of all species are receptive prior to anthesis and can be artificially pollinated at this stage provided that the stigma lobes can be separated. Pollen viability, tested for P. pandorana and P. jasminoides, deteriorated during the flower life although pollen samples with a low Fluorescein diacetate response (5-14%) still produced many pollen tubes which grew to the base of the style. For all species tested, pollen tubes grew into the ovary in both outcross pollinations and in self pollinations which are known to be incompatible indicating that the incompatibility barrier is within the ovary. Pollen-ovule ratios, determined for P. pandorana and P. jasminoides, were low compared with other published pollen-ovules ratios for taxa with breeding systems based on outcrossing.
Pasture Associations and Their Relation to Environment and Agronomy in the Goulburn District
Authors: Robinson JB , Munnich DJ , Simpson PC , Orchard PW
Published: December 2005

Pasture species form a variety of associations inn the cool temperate environment of the tablelands of New South Wales. Data from a survey of 65 paddocks on 34 farms in the Goulburn district of southern New South Wales were analysed using numerical classification methods to identify species associations. Of particular interest were the agronomic and environmental factors associated with the abundance of Danthonia spp. and Microlaena stipoides, which are persistent and useful native perennial grasses. The abundance of Danthonia spp. was negatively correlated with the abundance of exotic sown grasses (many species) and annual grass species (chiefly Vulpia spp.). M. stipoides abundance was similarly correlated with sown grass species, but had no correlation with annual grasses. It had a significant negative correlation with legume species abundance (chiefly Trifolium spp.). Sites with M. stipoides associations (n = 19 sites) had particular clearing and cultivation histories and low pH. Sites (n = 12) with a Danthonia spp. association also had particular clearing and cultivation histories, and occurred predominantly on soils derived from sedimentary parent material (11/12 sites). This association also had significantly higher annual average and total superphosphate usage. Probable mechanisms by which the concurrent environmental and agronomic factors may have determined the observed associations are discussed. It is concluded that the numerical classification system employed here revealed useful species association-site grouping units and contributed significantly to the interpretation of these data.
Environmental Correlates of Tree Species Diversity in Stage III of Kakadu National Park, Northern Australia
Authors: Bowman DMJS , Woinarski JCZ , Menkhorst KA
Published: December 2005

A quadrat based survey that sampled across the environmental range of the geologically and topographically diverse Stage III of Kakadu National Park, Northern Territory, revealed that the region has a tree flora dominated by the family Myrtaceae, and the genus Eucalyptus in particular. Principal components analysis (PCA) defined three axes of environmental variation: site rockiness, site hydrology and surface soil clay content. The three PCA axes were divided into halves and a 2x2x2 matrix was created to classify eight environments; however, there were quadrats in only seven of the eight possible environments. Kruskal-Wallis one-way ANOVAs showed that there was significant variation of the following variables between the 7 environments: total basal area, tree species richness, proportion tree richness composed of eucalypt species, and proportion of eucalypt richness composed of the four subgenera Blakella, Corymbia, Eudesmia and Symphyomyrtus. Of the most abundant 25 tree species and other common eucalypts only five species (Allosyncarpia ternata, Eucalyptus bigalerita, E. clavigera, E. foelscheana and E. jacobsiana) did not have significant differences in their mean basal area between the seven environments. The above patterns are interpreted as evidence that the savanna is a highly evolved system rather than the product of geologically recent disturbance to a once widespread monsoon rainforest.
Comparative Leaf Water Potentiais of Plants in Burnt and Unburnt Dry Sclerophyll Vegetation
Authors: Guo JM , Sinclair R
Published: December 2005

Leaf (xylem) water potentials were measured in summer and autumn on four species, Eucalyptus fasciculosa, Pultenaea daphnoides, Platylobium obtusangulum and Acacia myrtifolia growing in the understorey of sclerophyll stringybark vegetation in the Mt Lofty Ranges, South Australia. Plants regenerating in an area burnt by bushfire 2 years previously were compared with plants in an adjacent unburnt area. The Acacia was killed by fire and subsequently regenerated from seed. The other three species survived and resprouted from basal or epicormic buds. It was expected that shrubs regenerating from basal buds would be better hydrated in summer, as a large intact root system would supply a reduced canopy, and that seedlings, with smaller root systems than unburnt adults, would be more stressed. The Acacia was indeed significantly more stressed during summer in the burnt area. However the Platylobium was also more stressed than the controls, while the Pultenaea showed no significant differences between burnt and control areas. The Eucalyptus showed no differences between sites, nor between any of the three sampling times. The more negative water potentials of some of the regenerating plants are explained by greater exposure of surface soil on the burnt site, leading to more rapid drying of the surface soil in summer.
Monotoca-Type (Epacridaceae) Pollen in the Late Tertiary of Southern Australia
Authors: Martin HA
Published: December 2005

The shrub Monotoca is widespread in eucalypt forests. Monotoca-type pollen is distinctive with a tetrad of one large functional cell and three small aborted cells. Other variations on the tetrad, with equal sized cells, the normal pollen type for the family, cannot be confused with Monotoca. Fossil Monotoca pollen first appears in the Mid Miocene, when the climate was becoming drier, rainforest was contracting and sclerophyll forests were expanding.
Pathogenic Variability in Australian Isolates of Phytophthora cinnamomi
Authors: Dudzinski MJ , Old KM , Gibbs RJ
Published: December 2005

Forty-two isolates of Phytophthora cinnamomi were obtained from native vegetation and horticultural crops within Australia. They represented a broad spectrum of geographical and host origins, both mating types, and all identified Australian isozyme genotypes. All isolates were tested for their pathogenicity to a single clone of Eucalyptus marginata by inoculation of soil in which plants were growing. Differences in pathogenicity were expressed as extent of root damage, reduction of plant growth, period to first visible disease symptoms and time to plant death. Significant variation between isolates was detected. Pathogenicity was unrelated to mating type and isozyme properties. A subset of these 42 isolates encompassing a range of virulence gave generally consistent rankings for pathogenicity variates when re-inoculated twice into plants derived from the original clone. This suggests that pathogenicity is a relatively stable characteristic. Detection of differences in susceptibility to P. cinnamomi between three selected E. marginata. clones was influenced by the pathogenicity of isolates. Only the more pathogenic isolates were useful in this regard. Seedling stems of five eucalypt species were inoculated with virulent and less virulent isolates of P. cinnamomi. This method detected variation in both pathogenicity in the fungus and susceptibility in the host species. Variation in pathogenicity within Australian populations of P. cinnamomi should be taken into account by the choice of isolates of proven virulence when selecting for resistance in trees and other woody hosts.
Occurrence of Vesicular Mycorrhizal Fungi in Dryland Species of Restionaceae and Cyperaceae From South-West Western Australia
Authors: Meney KA , Dixon KW , Scheltema M , Pate JS
Published: December 2005

Species of Cyperaceae and Restionaceae were examined for presence of vesicular-arbuscular (VA) mycorrhizal fungi in natural habitat in south-west Western Australia. VA mycorrhizal fungi were detected in roots of two species of Cyperaceae (Lepidosperma gracile and Tetraria capillaris), and two species of Restionaceae (Alexgeorgea nitens and Lyginia barbata), all representing the first records for these genera. Results indicated a very short seasonal period of infection, with VA mycorrhizal fungi representing the genera Acaulospora, Glomus, Scutellospora and Gigaspora identified in roots. VA mycorrhizal fungi were prominent from late autumn to early winter (April-June) and in up to 30% of the young, new season's roots as they penetrated the upper 10 cm region of the soil profile. Mycorrhizal infection was not evident during the dry summer months. This study suggests that mycorrhizas may be important for nutrition of these hosts in these environments but their activity is restricted to a brief period of the growing season.
Effect of Fructose on Growth of Papaw Shoot Explants in vitro
Authors: Drew RA , Considine JA , Mccomb JA
Published: December 2005

The effects on papaw (Carica papaya L.) shoot growth of the carbohydrates sucrose, fructose, glucose and ribose singly and combined, were compared at a range of concentrations, in both autoclaved and filtered media. Fructose (10 g L-1), when autoclaved together with other media components, consistently promoted growth of shoots from buds on nodal sections or buds excised with a wedge of stem tissue. This enhancement was seen if the fructose was used singly or in combination with 10 g L-1 sucrose. By contrast, autoclaved media containing fructose reduced growth of small axillary bud explants. Decreasing the pH of fructose solution from 5.8 to 4.4 before autoclaving enhanced growth of buds from nodal sections. Other sugars in the D-ketose group inhibited papaw shoot growth totally when autoclaved with other media components. A radish cotyledon bioassay of solutions of fructose autoclaved singly or with NH4NO3 (20 mM) showed no evidence of cytokinin effects.
Variation in the Eucalyptus globulus Complex Revisited
Authors: Jordan GJ , Potts BM , Kirkpatrick JB , Gardiner C
Published: December 2005

Patterns of variation in the Eucalyptus globulus Labill. complex are reassessed by combining
capsule measurements from an earlier study with recent collections, mainly of subspecies
globulus. Four groups of populations are apparent and can be ascribed to the four subspecies
maidenii, pseudoglobulus, bicostata and globulus. Intergrade populations between the latter three
subspecies are widespread and mainly occur in the Otway Ranges and west Gippsland. There
is a continuum in capsule morphology between the three-fruited subspecies, pseudoglobulus and
bicostata. Subspecies globulus intergrades with these three-fruited intermediates. Three-fruited
intergrade populations occuning north and south of the range of core pseudoglobulus can be
differentiated and probably represent intergrades between pseudoglobulus and bicostata and
between pseudoglobulus and globulus respectively. Reports of bicostata in the Furneaux Group
and southern Victoria are thus probably erroneous and result from convergence in capsule
morphology. The previously described taxon E. stjohnii (R. T. Bak.) R. T. Bak. is part of
the continuum between subspecies pseudoglobulus and bicostata, but closer to pseudoglobulus.
Populations phenotypically intermediate between and significantly different from globulus and
the three-fruited intergrades are highly variable and occur in western Tasmania, on the northern
end of Flinders Island, in the Otway Ranges and in west Gippsland. An isolated population
on Rodondo Island is highly variable and has closest affinities to pseudoglobulus despite being
within the geographical range of core globulus. The population from King Island is intermediate
between the Otway phenotype and core globulus. The climatic regimes of the subspecies are
markedly different and most three-fruited and globulus intergrade populations have closer climatic
affinities to pseudoglobulus and globulus respectively. Hypotheses relating to the origin of the
pattern of variation in E. globulus are discussed.