Showing papers in "Australian Journal of Botany in 1976"
TL;DR: During the intensely competitive early decades, the height growth of Eucalyptus regnans is very rapid and the reduction of stem density most pronounced and the resultant large component of suppressed trees from this period is mostly eliminated before the spar stage at 40 years.
Abstract: During the intensely competitive early decades, the height growth of Eucalyptus regnans is very rapid and the reduction of stem density most pronounced. The resultant large component of suppressed trees from this period is mostly eliminated before the spar stage at 40 years. At this stage height growth diminishes although diameter growth is sustained. In addition, the crown cover is a maximum and light penetration is a minimum. The canopy cover increases with increasing angle from the zenith, and in winter the light interception by deep mature crowns is considerable. On warm, dry north-western slopes, pole stage stands are shorter and denser than those on moister, cooler south-eastern slopes. By the spar stage such stands are differentiated by stature only. The thinning out of dense even-aged understoreys of Pomaderris aspera is inversely proportional to the density of the overstorey of E. regnans. The thinning out of E. regnans from the pole stage is independent of the type of understorey. The most intense competition between E. regnans and P. aspera is likely to occur in the first decade when the root systems of the two species are of similar form.
226 citations
TL;DR: The likely C4 type of 255 biochemically-untyped grass species was deduced by direct observation or from Metcalf's anatomical descriptions and all 124 C4 species examined, including C3 eu-panicoids, proved to be XyMS+.
Abstract: Transections of leaf blades from 46 C4 grass species of known C4 type were recorded for presence (XyMS+) or absence (XyMS-) of cells intervening between metaxylem vessel elements and laterally adjacent chlorenchymatous bundle sheath cells of primary lateral vascular bundles. A perfect correlation, only 'NADP-ME type' species being XyMS-, indicated that XyMS type serves as a useful predictor of C4 species type. The likely C4 type of 255 biochemically-untyped grass species was accordingly deduced by direct observation (94 spp.) or from Metcalf's anatomical descriptions (161 spp.). All 124 C4 species examined, including C3 eu-panicoids, proved to be XyMS+.
124 citations
TL;DR: Changes in soil moisture under various densities of mulga (Acacia aneura F. Muell.) were followed from December 1971 to October 1973, demonstrating the ecological importance of stem flow and soil moisture patterning to the survival and growth of mulGA and associated ground flora.
Abstract: Changes in soil moisture under various densities of mulga (Acacia aneura F. Muell.) were followed from December 1971 to October 1973. Stemflow was instrumental in storing water at depth in the soil, being particularly noticeable with medium falls of rain (~ 75 mm); heavy (~ 160 mm) falls tended to mask the effect. Throughfall increased linearly with aggregate rainfall, and percentage throughfall decreased with increasing tree density. Of incoming precipitation, 94% was partitioned as throughfall under a tree density of 40 trees/ha-1 compared with 86% at a density of 4000 trees/ha. No distinct soil moisture patterns due to throughfall were found. Infiltration rates of water into the soil decreased with increasing distance from trees, being 46, 22 and 17 mm/h-1 after 10 min at distances 0.25, 0.5 and 2 m from a tree bole respectively, thus demonstrating that stemflow waters are absorbed at close proximity to the tree bole.The results are discussed in terms of the ecological importance of stem flow and soil moisture patterning to the survival and growth of mulga and associated ground flora.
107 citations
TL;DR: Growth of sclerophyll species on areas subject to disturbance will be determined in large part by the levels of phosphorus and nitrogen applied and the rate at which nutrients are leached from the rooting zone.
Abstract: Seedlings of Banksia serrata, Acacia suaveolens and Eucalyptus pilularis were grown in sand culture for 3-4 months at four levels of phosphorus (0, 5, 50, and 100 ppm) and three of nitrogen (0, 25 and 250 ppm) applied gradually in all combinations. B.serrata died at high phosphorus-high nitrogen levels, A.suaveolens died with high phosphorus irrespective of the nitrogen level, and E. pilularis did not survive high phosphorus or high nitrogen levels. There were differences between species in their growth responses to increasing levels of phosphorus and nitrogen. Dry weights of seedlings were greatest at P5N25 for B.serrata, at P5N250 for A.suaveolens, and at P5N250 for E.pilularis. Shoot phosphorus concentrations greater than 1% were directly associated with 'toxicity' and death of A.suaveolens seedlings only, and not of the other two species. The species differ in the weights and nutrient contents of their seeds, and this is discussed in relation to the different responses obtained. Growth of sclerophyll species on areas subject to disturbance (e.g. sand-mining) will be determined in large part by the levels of phosphorus and nitrogen applied and the rate at which nutrients are leached from the rooting zone.
85 citations
TL;DR: The morphology, reproduction, and relationships of the southern Australian species of three closely related families of the Gigartinales (Solieriaceae, Rhabdoniaceae and Rhodophyllidaceae) are described and procarpy has arisen, by loss of ability to form connecting filament, from a non- procarpic ancestor such as Areschougia.
Abstract: The morphology, reproduction, and relationships of the southern Australian species of three closely related families of the Gigartinales (Solieriaceae, Rhabdoniaceae and Rhodophyllidaceae) are described. In the multiaxial Solieriaceae, most genera of which are non-Australian, Solieria robusta (Greville) Kylin and five species of Callophycus Trevisan have been studied. Apart from Sarconema filiforme (Sonder) Kylin, these are the only southern Australian taxa retained in the family. In the uniaxial and non-procarpic Rhabdoniaceae, Rhabdonia Hooker and Harvey (three species), Catenella nipae Zanardini, Areschougia Harvey (three species), and Erythroclonium Sonder (four species) have been studied. A species previously placed in Areschougia, A. dumosa Harvey, is found to be procarpic and is described as a new genus, Melanema. In all other vegetative and reproductive features it is similar to Areschougia, and it is provisionally retained in the Rhabdoniaceae. In the uniaxial and procarpic Rhodophyllidaceae the following are studied: Rhodophyllis Kuetzing (four species), Craspedocarpus Schmitz (four species, previously placed in Rhodophyllis), Gloiophyllis barkeriae (Harvey) J . Agardh, Calliblepharis planicaulis (Harvey) Kylin, and a new genus Austroclonium, based on Rhabdonia charoides Harvey.The main features used by Kylin in separating and characterizing these families and genera are considered generally satisfactory, but there appear to be cases where they cannot be rigidly applied. Such cases include the direction of gonimoblast development, and in the case of Melanema it is suggested that procarpy has arisen, by loss of ability to form connecting filament, from a non- procarpic ancestor such as Areschougia.
69 citations
TL;DR: The germination and dormancy of Themeda australis, Danthonia spp.
Abstract: The germination and dormancy of Themeda australis, Danthonia spp., Stipa bigeniculata and Bothriochloa macra were investigated in whole dispersal units or caryopses. Germination of non-dormant units of the four species was not affected by light but was delayed by low temperatures. Such temperature regimes depressed the germination capacity of Themeda while alternating temperatures with a range greater than 10°C depressed the germination of Bothriochloa. The level of germination of Danthonia and Stipa was not affected by any of the temperature regimes used. Dormancy was reduced either by the application of gibberellic acid at concentrations of 100 ppm to 1000 ppm or by stratification. In addition, application of kinetin ( 10 -4M ) or opening the lemma suture broke the dormancy of Stipa dispersal units. The breakdown of dormancy during dry storage was also examined. Temperature alternations with maximum temperatures greater than 40°C reduced the level of dormancy of Themeda and Stipa within 1-2 months.
67 citations
TL;DR: Borya nitida, a perennial tufted herb, grows in south Western Australia as a pioneer plant codominant with lichens on exposed rock outcrops, and on bare sands with low water-holding capacity and rapid drainage.
Abstract: Borya nitida, a perennial tufted herb, grows in south Western Australia as a pioneer plant codominant with lichens on exposed rock outcrops, and on bare sands with low water-holding capacity and rapid drainage. The mature leaves of the plant are capable of reviving after desiccation; they develop drought tolerances of 0% relative humidity (RH) under field conditions. The rate of drying is critically important for the development of desiccation tolerance. Drought-avoidance mechanisms (possibly related to the xeromorphic features of the plant) slow the rate of dehydration sufficiently for the development of full drought tolerance which requires completion of a time-dependent tolerance-endowing process in the range of water potential around 96% RH (90-98%), as well as avoidance of a slower time-dependent injurious process at water potentials of 75% RH and above. Non-senescent leaves that fulfil both requirements remain viable at water potentials below 50% RH for years. Dry viable leaves are yellow, owing to the loss of chlorophyll during the former process. Induction of drought tolerance at moderate water stress has been reported in other species, but Borya is remarkable for the extreme rapidity of the process and the degree of tolerance developed.
67 citations
TL;DR: Experiments suggest that a transfer of carbon-14 takes place from the leaves to the mycorrhizal mantle, and the earliest stages of infection of new roots appear to occur via root hairs, and intracellular hyphae are produced.
Abstract: Eucalyptus regnans mycorrhizae vary from simple to coralloid forms, and their surfaces are commonly smooth or conspicuously enmeshed with external mycelium. At least 18 different basidiomycetes may be intimately associated with dense weft-type mycorrhizae; six agarics have been induced to form simple or diffuse mycorrhizae under sterile conditions. Individual mycorrhizae vary in form and colour with both age and the nature of the symbiont. In the field, mycorrhizae are longer-lived than uninfected lateral roots. The earliest stages of infection of new roots appear to occur via root hairs, and intracellular hyphae are produced. This is rapidly followed by the development of either ectendotrophic, ectotrophic or superficial mycorrhizae. Mycorrhizal development is enhanced by high light intensity, diminished by high levels of nitrogenous fertilizer, but apparently unaffected by high levels of phosphate. Experiments suggest that a transfer of carbon-14 takes place from the leaves to the mycorrhizal mantle. Inoculation of E. regnans by Mesophellia arenaria in relatively rich loams of south Gippsland improved the growth of E. regnans seedlings in both field and the glasshouse. The sterilization by gamma-rays of krasnozem topsoil from the forest improved the growth of E. regnans seedlings. Growth of seedlings was further enhanced by the inoculation of such soil with a mycorrhizal fungus (probably inocybe olivaceofulvus).
59 citations
TL;DR: The genus Griffithsia C. Agardh, with its type species G. corallinoides (L.) Batters, is characterized by subdichotomous filaments of large multinucleate cells; by a fertile axis of three small discoid cells of which the subapical cell produces 1(-2) procarp(s), whilst the lowermost cell (termed the hypogenous) produces abaxially an involucre of 2-celled branches.
Abstract: The genus Griffithsia C. Agardh, with its type species G. corallinoides (L.) Batters, is characterized by subdichotomous filaments of large multinucleate cells; by a fertile axis of three small discoid cells of which the subapical cell produces 1(-2) procarp(s), whilst the lowermost cell (termed the hypogenous) produces abaxially an involucre of 2-celled branches; by a large fusion cell; and by the production of tetrasporangia and spermatangia on whorls of fascicles which often bear involucral cells, or are surrounded by an involucre from the vegetative cell beneath the fascicles, or are naked. Some southern Australian species previously placed in Monosporus Solier or Neomonospora Setchell & Gardner, but which produce tetrasporangia and reproduce sexually, are related to G. tenuis C. Agardh and G. barbata C. Agardh. They are characterized by subdichotomous filaments of multinucleate elongate cells; by a 3-celled fertile axis of which the subapical cell produces a procarp, and the hypogenous cell enlarges during procarp development and produces a whorl of 1-celled involucral branches; by a large fusion cell; and by tetrasporangia and spermatangial heads produced singly either from the basal cell of a trichoblast, or on a separate clavate pedicel. These species are referred to the genus Anotrichium Naegeli, differing from Griffithsia mainly in the spermatangial heads and tetrasporangia. The genus Monosporus Solier, represented with certainty in southern Australia only by M. australis (Harvey) J . Agardh, is retained as a form genus for those species which produce monosporangia but for which sexual reproduction is unknown. Study of Halurus equisetifolius (Lightfoot) Kuetzing, the type species of Halurus Kuetzing, from England, shows that this genus is characterized by irregularly branched axes with dichotomous whorl-branchlets; by the successive production of several fertile axes each of 3 small cells and equivalent to a condensed, dichotomous, branch system; and by a subapical procarp and large fusion cell. The involucre consists of vegetative whorl-branchlets and also a whorl of 1-celled branches from the enlarged hypogenous cell of the fertile axis. Halurus thus differs from Griffithsia mainly in cystocarpic features and the presence of whorl-branchlets. Griffithsia setacea (Ellis) C. Agardh should probably be referred to Halurus. An evolutionary trend towards reduction in the Griffithsieae is suggested: whorl-branchlets have been reduced to trichoblasts and fertile whorl-branchlets to whorls of fascicles. The number of procarps in a branch system and the female, spermatangial and tetrasporangial involucres show a reduction sequence.
57 citations
TL;DR: The amount of vascular tissue in the funicle and ovule increases markedly between the time of cotyledon initiation and the commencement of storage protein synthesis and deposition.
Abstract: The pea seed requires large quantities of nutrient during its growth and development. In the early stages a large proportion of this nutrient is obtained from the endosperm surrounding the embryo in the embryo sac. A number of structural specializations, such as increased surface areas of the embryo sac boundary wall and the extra-embryonic wall and breakdown of the inner ovular cells, may aid in the passage of nutrient to the developing embryo. This study has shown that the amount of vascular tissue in the funicle and ovule increases markedly between the time of cotyledon initiation and the commencement of storage protein synthesis and deposition. Large numbers of transfer cells are associated with the sieve elements in the pod and funicle, but not in the ovule. Also, the numbers of xylem and sieve elements in the funicle decrease as the strand passes from the pod to the ovule. Two strands of phloem tissue were found to branch from the main vascular bundle in the ovule and to sweep across the base of the seed and around either side of the narrow tubular arm of the embryo sac which contains the radicle.
56 citations
TL;DR: It is suggested that the induction of desiccation tolerance in the initial stages of drying may be associated inter alia with the production of additional mitochondria and of additional sugar by starch hydrolysis; both processes would tend to ensure a supply of respiratory ATP to support reconstruction of the metabolic system during rehydration.
Abstract: The dry viable leaves of Borya nitida show degeneration of the protoplasm: bounding membranes of chloroplasts and mitochondria are vague and the former display extensive gaps, starch and grana are lost, while thylakoids and cristae are considerably reduced in number. The nucleus and nucleoli retain their integrity, as does also the tonoplast, even though the vacuole is fragmented. It appears that stress-induced degeneration of organelles is similar to that in desiccation-sensitive plants but occurs to a controlled level, at which a sufficient residual structure is still present to initiate the reconstruction of the cell fine structure on rehydration. During the recovery of the cell on rehydration, the degraded plastids appear to repair the bounding membranes and produce new thylakoids which, at the start of regreening, begin to form grana and starch grains. Mitochondria are fewer but better structured in the regreened leaf. It is suggested that the induction of desiccation tolerance in the initial stages of drying may be associated inter alia with the production of additional mitochondria and of additional sugar by starch hydrolysis; both processes would tend to ensure a supply of respiratory ATP to support reconstruction of the metabolic system during rehydration.
TL;DR: Both H. leporinum and H. glaucum showed wide ecotypic variation in regard to flowering time, and this was related to length of growing season in South Australia and Victoria, suggesting both species were introduced into Australia well before the Suez Canal opened in 1869.
Abstract: Barley grass (in Australia usually called Hordeum leporinum Link) was collected at 88 sites in South Australia and Victoria and grown at Northfield, near Adelaide, S.A. Time to Aowering was noted and each line was identified taxonomically. Specimens from the Australian herbaria were examined. The material was shown to belong to the three species within the Hordeum murinum complex. H. murinum L. itself is restricted to near Hobart, Tasmania, but H. leporinum grows widely through the wetter parts of southern Australia: it seems to grow commonly as far north as Sydney, and in South Australia and Victoria where the rainfall exceeds c. 425 mm. H. glaucum Steud., the third species in the complex and not previously recorded in Australia, was shown to be the common barley grass in the semiarid zone of the southern States (<425 mm of rain), and in wetter regions in northern New South Wales and southern Queensland. Both H. leporinum and H. glaucum showed wide ecotypic variation in regard to flowering time, and this was related to length of growing season in South Australia and Victoria. The relationship was closest in H. leporinum. The first specimens of both H. leporinum and H. glaucum were collected in the 1840s and 1850s. Thus both species were introduced into Australia well before the Suez Canal opened in 1869. This eliminates the eastern Mediterranean as a direct source of the H. murinum complex even though the European distribution of one member, H. glaucum, is apparently limited to that region. Four other possible origins-England, the Atlantic coast and islands of Europe and north Africa, South Africa, and India-are discussed in relation to the distribution of the species and their opportunities for being introduced.
TL;DR: Banksia ornata is a sclerophyll shrub, characteristic of the heaths of south-eastern Australia, whose follicles are almost entirely dependent on fire for rupture and release of seed, although a few open under ambient field conditions.
Abstract: Banksia ornata is a sclerophyll shrub, characteristic of the heaths of south-eastern Australia. Its follicles are almost entirely dependent on fire for rupture and release of seed, although a few open under ambient field conditions. At air-dry moisture content (10-12% oven-dry weight) temperatures in excess of about 75°C are required for the rupture of the abscission layer between the woody valves, the time of exposure necessary for rupture decreasing with increasing temperature. At higher moisture contents rupture is delayed. No rupture occurs when follicles are water-saturated and exposed to a temperature of 100° over long periods. Similarly, no rupture occurs at room temperature when follicles are dried under vacuum (to 1.4% oven-dry weight). After rupture, the extent of valve reflexion is greatest when follicle valves are driest. These results are interpreted as follows. Follicle rupture occurs when tension across the abscission zone exceeds its strength: moisture has a major role in affecting the tension, and temperature a major role in affecting the strength.
TL;DR: Proteoid and non-proteoid roots are produced only during winter-spring under the Mediterranean climatic conditions of south-western Australia, however, dormant roots can be induced to form new root structures in summer, if sufficient water is applied to that part of the root system.
Abstract: Proteoid and non-proteoid roots are produced only during winter-spring under the Mediterranean climatic conditions of south-western Australia However, dormant roots can be induced to form new root structures in summer, if sufficient water is applied to that part of the root system The seasonal occurrence of proteoid roots is therefore due to the annual variation in water available for growth of the surface parent roots Both proteoid and non-proteoid root growth increase as water availability is increased from the permanent wilting point to one to two times field capacity, with a trebling in the proportion of proteoid roots by weight in the root system This is followed by a steep decline in total root weight and in the proportion of proteoid roots in the root system as water availability is increased from two to three times field capacity While the size of proteoid roots is greatest under non-waterlogged conditions (redox potential of 450-550 mV), their number per unit total root weight is greatest under moderately waterlogged conditions (redox potential of 120-350 mV)
TL;DR: A comparative study of the anatomy of the root systems of 12-week-old intermediate seedlings found the species could be distinguished by differences in cortex persistence and in the rate of polyphenol accumulation, but it was recognized that such differences were dependent on the age and growth rates of the roots sampled and could not be correlated with the differing susceptibilities of the two eucalypt species to Phytophthora cinnamomi.
Abstract: The two eucalypt species Eucalyptus obliqua and E st johnii differ in their susceptibility to Phytophthora cinnamomi, which infects their roots A comparative study of the anatomy of the root systems of 12-week-old intermediate seedlings was made, the material used ranging in size from the finest roots to first order laterals The root anatomy of the two species was similar but the species could be distinguished by differences in cortex persistence and in the rate of polyphenol accumulation However, it was recognized that such differences were dependent on the age and growth rates of the roots sampled and could not be correlated with the differing susceptibilities of the two eucalypt species to Phytophthora cinnamomi The walls of the exodermis and endodermis in both species are suberized and the ultrastructure of these walls was examined Broad bands of suberized lamellae completely lined the exodermal cells in the zone of differentiation In mature root zones the external radial walls of the epidermis were thickened and contained polyphenols The roots which had commenced secondary thickening developed a specialized periderm, a polyderm, which consisted of alternating layers of suberized and non-suberized cells
TL;DR: A. smithii is extremely shade-tolerant and regenerates readily under dense forest canopy and in gaps, and this characteristic is correlated with its restriction to low altitudes in a mild maritime environment.
Abstract: The Acmena smithii species complex occurs in a wide range of rain-forests (closed-forests) from 11° to 39° S. in eastern Australia. At its southernmost limit on Wilson's Promontory, it forms a structurally and floristically simple closed-forest of the microphyll fern type, and usually occurs up to altitudes of 300 m on relatively fertile alluvial and colluvial soils. It is replaced by thickets of Melaleuca spp. on very waterlogged soils and by nanophyll mossy forests of Nothofagus cunninghamii and Atherosperma moschatum at higher altitudes. It is often associated with emergent fire-induced strata of Acacia melanoxylon and Eucalyptus obliqua. On Wilson's Promontory, A. smithii rain-forest is a climax in fire-sheltered lowland gullies. In the prolonged absence of fire many adjacent wet sclerophyll (tall-open) forests are replaced by such rain-forest. A. smithii is extremely shade-tolerant and regenerates readily under dense forest canopy and in gaps. The seed is easily killed by desiccation and is frequently decimated by birds and insects. Slow development of seedlings in the first year renders them susceptible to drought and browsing. After the second year they are extremely persistent owing to the development of a lignotuber. The litter fall is heavy and decays rapidly to form a mull humus on relatively fertile loams and poor podzolic soils. The shoots of A. smithii grow during the frost-prone seasons of the year. This characteristic is correlated with its restriction to low altitudes in a mild maritime environment. The problems of the dispersal and past distribution of A. smithii are briefly discussed.
TL;DR: No leachable inhibitor seems to be the cause of dormancy, but the action of oxidizing agents such as hydrogen peroxide and the measurement of oxygen uptake by full or empty spikelets suggest that a restriction of gas exchange by the hull is responsible.
Abstract: Sowing is the most common way of establishing Brachiaria ruziziensis in pastures, but seed germi- nation is poor as a result of dormancy. The mechanism of dormancy is clearly located in the hull, for removing the hull or cutting at the base of the spikelet stimulates germination. No leachable inhibitor seems to be the cause of dormancy. However, the action of oxidizing agents such as hydrogen peroxide and the measurement of oxygen uptake by full or empty spikelets suggest that a restriction of gas exchange by the hull is responsible.
TL;DR: A palynolological investigation of Upper Tertiary sediments was carried out by analysis of core samples from Iviri No. 1 well, drilled by the Australasian Petroleum Company Pty Ltd, in the Central Delta region of Papua, and the new combination Stenochlaenidites papuanus is proposed for a pteridophyte species.
Abstract: A palynolological investigation of Upper Tertiary sediments was carried out by analysis of core samples from Iviri No. 1 well, drilled by the Australasian Petroleum Company Pty Ltd, in the Central Delta region of Papua. Descriptions are given of six new form genera: Ophioglossumporites (Pteridophyta), Hakeidites, Guettardidites, Canthiumidites, Planchoniidites and Malvaceidites (Angiospermae). New species described are Ophioglossumsporites novaguineensis, Gleicheniidites major, Klukisporites ivirensis, Baculatisporites papuanus, Cingulatisporites papuanus, C. ivirensis, C. psilatus, Polypodiisporites foveoirregularis, and Microfoveolatosporites psilotiformis (Pteridophyta), Hakeidites martinii, Guettardidites ivirensis, Canthiumidites reticulatus, Planchoniidites areolatoides, Malvaceidites spinosus, Dicolpopollis metroxylonoides, Diporites barrellus, Diporites papuanus, Triporopollenites ulmiformis, Proteacidites heliciformis, P, knightiiformis, P. papuanus, Malvacipollis problematicus, Malvacerumpollis papuensis, Juglanspollenites polyporus, Rhoipites antidesmiformis, Discoidites novaguineensis, Extratriporopollenites elaegniformis, Tricolpites rubioides, Tricolpites tertiarius, Polyadopollenites gigantea (Angiospermae), and Tasmanites novaguineensis (Algae).' The new combination Stenochlaenidites papuanus is proposed for a pteridophyte species.
TL;DR: Honeyeaters and silvereyes take the nectar, brush against the flowers and could effect pollination, and Insects also visit the nectaries and flowers and may act as an additional attractant to the birds.
Abstract: Acacia pycnantha, like many members of its genus, produces nectar from a gland at the base of the petiole. Nectar is apparently produced only when the plant is flowering and only on petioles close to the inflorescences. The nectary seems poorly placed to attract insect pollinators, but honeyeaters and silvereyes take the nectar, brush against the flowers and could effect pollination. Insects also visit the nectaries and flowers and may act as an additional attractant to the birds.
TL;DR: A taxonomic account of the genus Datura in Australia is presented and the application of names is in accordance with current usage, some nomenclatural problems are outlined.
Abstract: A taxonomic account of the genus Datura in Australia is presented. Wild populations of D. stramonium, D. ferox, D, leichhardtii, D, inoxia and D. wrightii occur and D. metel is cultivated and occasionally persistent. A comprehensive revision of the genus has not been attempted, but full descriptions based on a study of herbarium specimens, plants in the field and cultivated material are provided for each of the six species, of which five are naturalized aliens. D. leichhardtii has generally been considered an Australian endemic but the closely related species D. pruinosa (which may be conspecific) occurs in central America. This raises the biogeographical problems of trans-Pacific distribution. Although the application of names is in accordance with current usage, some nomenclatural problems are outlined. A key for the identification of species is presented. The genus Brugmansia, often treated as a section of Datura, is represented in Australia only by species in cultivation.
TL;DR: Variations in growth temperatures produced structural changes in surface waxes as previously reported but no specific correlation could be found between changes insurface fine structure and variations in subcellular morphology.
Abstract: Incorporation of 1-14C-palmitic acid, a precursor of leaf waxes, into leaf strips of Brassica napus was examined by thin section autoradiography and electron microscopy. Label was found to be associated with mitochrondria, Golgi vesicles and endoplasmic reticulum of epidermal cells, and also with the outer epidermal wall across which cuticular lipids are expected to migrate. Variations in growth temperatures produced structural changes in surface waxes as previously reported but no specific correlation could be found between changes in surface fine structure and variations in subcellular morphology. It is concluded that variations in wax fine structure, as influenced by growth temperature, resulted from effects at the biochemical level.
TL;DR: Chromosome numbers are given of about 100 species of Solanum native, naturalized or cultivated in Australia, the majority of them new records, including several new records of polyploid races of two species.
Abstract: Chromosome numbers are given of about 100 species of Solanum native, naturalized or cultivated in Australia, the majority of them new records. The origin and distribution of polyploid races of two species is briefly discussed.
TL;DR: Three patterns of disease extension were observed in areas of uncultivated shrubby dry sclerophyll forest invaded by the pathogen Phytophthora cinnamomi, showing that absence of disease Extension for 4 years in highly susceptible vegetation may be associated with differences in soil characteristics.
Abstract: Three patterns of disease extension were observed in areas of uncultivated shrubby dry sclerophyll forest invaded by the pathogen Phytophthora cinnamomi. Environmental factors were found to determine which pattern developed. Where inoculum was spread downhill with drainage water, diseased areas were separated by clearly defined boundaries from unaffected vegetation. Where disease extension occurred uphill through soil or from root to root, a wavy boundary marked the active disease front. Investigations showed that absence of disease extension for 4 years in highly susceptible vegetation may be associated with differences in soil characteristics.
TL;DR: It is concluded that along the latitudinal and climatic gradient there has been no significant change in temperature optima for growth but there have been natural selection resulting in higher growth rates of northern populations.
Abstract: Five populations of the indigenous perennial grass Danthonia caespitosa Gaud. were selected from widely separated sites along a north-south transect in south-eastern Australia. The sites, spanning the latitudinal range (31° to 42° S.) for the species, extended from a hot semiarid environment in the north to a cool and moist temperate environment in the south. Two experiments, to assess the extent of intraspecific variability in response to different tempera- ture regimes, were conducted in naturally lit temperature-controlled glasshouses in the Ceres phyto- tron. All populations had a similar temperature optimum for growth of between 20.7 and 267°C (mean daily temperature), typical for temperate species. Rates of tillering, rates of leaf appearance, and leaf blade lengths and widths differed among populations and showed considerable phenotypic plasticity with respect to temperature. At all temperatures the growth rate of populations generally declined with increasing latitude of origin. A detailed analysis of growth rates showed that differences between populations in final weight could largely be accounted for by variability in mean relative growth rates. Northern populations in general had a higher net assimilation rate and leaf weight ratio than southern populations. The adaptive significance of these physiological and morphological differences between populations is discussed in relation to habitat characteristics and the distributional range of the species. It is concluded that along the latitudinal and climatic gradient there has been no significant change in temperature optima for growth but there has been natural selection resulting in higher growth rates of northern populations.
TL;DR: It has been found that the pattern of young individuals may be correlated with patterned variation in microtopography, as well as with water and nutrient availability, and that the indirect effects of grazing animals may be responsible for the intermediate scales of the mosaic pattern in populations of sexually mature individuals.
Abstract: The majority of pattern analyses of total density data collected from geographically separated populations of Atriplex vesicaria, both in the western Riverine Plain of New South Wales and in areas of north-western New South Wales, provided evidence of bi- or trimodal contagion. More detailed analyses of pattern in age-related phases of these populations exhibited most intense patterning in 'seedling' phases, with a progressive reduction of pattern intensity in subsequent ('pioneer', 'building' and 'mature') phases of the entire population. It has been found that the pattern of young individuals may be correlated with patterned variation in microtopography, as well as with water and nutrient availability, and that the indirect effects of grazing animals may be responsible for the intermediate scales of the mosaic pattern in populations of sexually mature individuals. The performance of A. vesicaria plants was assessed experimentally in relation to a range of natural soils, with associated watering and defoliation treatments, and in controlled nutrient solution culture. The results suggest that performance (as estimated by dry weight yield) is affected significantly by soil type, water stress and defoliation. In an experimental context the prime effect of soil variation on yield appeared to be mediated by variation in soil cation balance, a patterned balance that may have been historically induced in the field situation.
TL;DR: Inoculation with the crushed fruiting body of Pisolithus tinctorius induced more than 70% of tested Eucalyptus gummifera seedlings to form mustard yellow mycorrhizas when the phosphorus concentration was optimal, but the formation of mycor rhizas was dependent on the phosphorus concentrations.
Abstract: A simple method of producing mycorrhizas is described which enables mycorrhizal plants to be used in a wide range of experiments including controlled nutritional studies of Eucalyptus. Plants are grown in a Leonard jar apparatus under either sterile or non-sterile conditions, on soil or pure crushed quartz with nutrient solution media. On the sterile quartz media, inoculation with the crushed fruiting body of Pisolithus tinctorius induced more than 70% of tested Eucalyptus gummifera seedlings to form mustard yellow mycorrhizas when the phosphorus concentration was optimal, but the formation of mycorrhizas was dependent on the phosphorus concentration. No mycorrhizas were formed when phosphorus exceeded 5 ppm. On non-sterile, nutritionally poor Hawkesbury sandstone soils 92% of inoculated plants were infected. Only a few of the non-inoculated plants in either medium were lightly infected. A simple but reliable method for inducing mycorrhizas is proposed.
TL;DR: 227 genera of Australasian grasses, classified with reference to anatomical and morphological attributes, are referred to major taxonomic groups.
Abstract: 227 genera of Australasian grasses, classified with reference to anatomical and morphological attributes, are referred to major taxonomic groups. Group diagnoses are supplemented by quantitative information on attributes showing taxonomic bias.
TL;DR: Alexgeorgea is highly distinctive in bearing single-flowered female inflorescences on sessile horizontal rhizomes c.
Abstract: The genus Alexgeorgea is described as new to science. Two species were discovered during field work in 1974: A. subterranea, from the Jurien Bay-Badgingarra sandplain, W.A., and A. arenicola, from sand areas short distances north and east of Perth. Alexgeorgea is highly distinctive in bearing single-flowered female inflorescences on sessile horizontal rhizomes c. 10-15 cm below the sand surface. In flower, only the tips of the bracts and the three ephemeral styles appear above the ground, so that female flowers are invisible most of the year and inconspicuous even at anthesis. Fruits are exceptionally large for Restionaceae, indehiscent, one-seeded and borne sessile on underground rhizomes. Difficulty in dispersal of these fruits would explain the existence of presumptive all-female colonies of A. arenicola which may have originated from single-fruit introductions to sites at the periphery of the range of that species. Increase in the size of colonies is mostly vegetative, by branching of the elongate subterranean rhizomes. It is suggested that the underground flowering and fruiting habit is related to fire resistance. Alexgeorgea appears most closely related to Western Australian species of Restio on account of striking vegetative similarities. The two species of Alexgeorgea are illustrated by habit photographs and macrophotographs of living plants taken during the field work.
TL;DR: Experiments to determine the roles of Phytophthora cryptogea and waterlogging in a decline of Pinus radiata showed that the fungus affected young pines up to 1 year old when associated with water- logged soil.
Abstract: Experiments to determine the roles of Phytophthora cryptogea and waterlogging in a decline of Pinus radiata showed that the fungus affected young pines up to 1 year old when associated with water- logged soil. In drier soil, similar plants were affected by the fungus only when they had originally been transplanted to the test pots. However, waterlogging affected both transplanted and non-trans- planted young trees in both the presence and absence of the fungus. Thus waterlogging is an important factor in the decline of young Pinus radiata. A similar situation probably exists with regard to older trees growing on very wet sites.
TL;DR: Palynological investigations were carried out on 16 samples from a core of Iviri No. 1 Well in the Central Delta region of Papua New Guinea, finding nine species belonging to the genera Araucariacites, Podocarpidites, Lygisfepollenites, Dacrycarpites, Microcachryidites and Ginkgocycadophytus.
Abstract: Palynological investigations were carried out on 16 samples from a core of Iviri No. 1 Well in the Central Delta region of Papua New Guinea. The age range is from Upper Miocene to Recent. Nine species belonging to the genera Araucariacites, Podocarpidites, Lygisfepollenites (Dacrydiumites), Dacrycarpites, Microcachryidites, Trisaccites, Ginkgocycadophytus and Ephedra are described. Ginkogocycadophytus novaguineensis is described as new. The distribution of gymnosperms in the Neogene epoch in Australasia is discussed in the light of this fossil record.