Australian Journal of Botany最新文献

To examine the potential applications of hyperaccumulator plants in the Philippines, we reviewed current data on the extent of metal hyperaccumulation in native species and partitioning of metals within the plant tissue. Twenty-eight species had reported tissue concentrations above the hyperaccumulator threshold, 11 species were endemic to the Philippines. Nickel was present in higher concentrations in the aboveground tissue than in the belowground tissue, but the reverse was found for copper, aluminium and chromium. The fact that copper accumulates belowground rather than above, and most hyperaccumulators of nickel identified were trees, has implications for the potential of phytoextraction using native Philippines flora.

The Chromolaena congesta complex is an informal group of taxa native to grasslands from south-eastern South America with numerous identification problems, currently under study using an integrative approach. Recent studies with morphological data have aided in defining some taxa, but many questions remain to be assessed, and there is much to gain from combining morphological data with other lines of evidence.

We investigated whether the species of the C. congesta complex could be circumscribed and differentiated according to climatic and distributional data and how these results compare to published morphological data.

We used a SDM approach and climatic envelope estimates of 12 taxa belonging to the C. congesta complex. To achieve that, we compiled a distributional database from herbarium specimen information and produced distribution models for each taxon by using MaxEnt and 19 bioclimatic variables.

We found that many species of the complex share similar predicted suitable distribution and climatic preferences, while also uncovering particular geographic and climatic patterns for C. ascendens and C. caaguazuensis. Our results also contributed with the circumscription of C. squarrulosa and provided data for further recognition of two taxonomic novelties.

Climatic and distributional data yielded interesting results for the taxonomy of this species complex, particularly when confronted with morphological data.

This study provided support for an apparently undescribed Chromolaena that merits recognition at species rank and the treatment of Eupatorium caaguazuense var. nervosum as a separate species from C. squarrulosa, while also supplying further evidence that morphologically diverse populations of C. squarrulosa should be treated as a single taxon.

The dynamics of a plant population are influenced by both biotic and abiotic factors that interfere with the phenotype of the individual, indicating how species develop in the occupied environment. Riparian plant species are subject to environmental fluctuations, such as periodic flooding regimes and severe droughts, which may result from climate change.

The aim of this study was to evaluate the morphological growth responses of individuals of Inga vera subsp. affinis (DC.) T.D.Penn. in controlled drought and flooding conditions by observing variations in functional traits using controlled experiments.

Individuals were subjected to partial flooding and dry periods, and functional traits, such as leaf area, root height and dry mass, were analysed. The difference between treatments was tested using unifactorial statistical analysis of variance (ANOVA).

Fifteen-day-old individuals of Inga vera subsp. affinis kept under flooding conditions showed lower root height and dry mass compared to plants exposed to drought treatment; 50-day-old plants under flooding conditions also presented lower root dry mass than did plants in drought treatment, maintaining the result after the resilience period.

Root dry mass was the most affected variable in individuals of Inga vera subsp. affinis under flooding conditions, even after the recovery period. In general, plants in the control and drought treatments did not differ significantly considering the analysed variables.

Given the current climate change conditions, an increase in the frequency and duration of extreme events, such as floods and droughts, is expected. Thus, understanding how phenotypical traits of species already adapted to flooding conditions behave under water stress and waterlogged conditions for longer periods of time is essential to explain plant responses and predict future survival scenarios for the species.

Knowledge of seed biology is imperative for effective curation and utilisation of seeds.

We studied the seed biology and reproduction of Geijera parviflora, a species suitable for ecological restoration and ornamental horticulture that has largely been overlooked because of issues with unreliable germination and viability.

Germination in response to dormancy-breaking treatments and soil seed burial, and variation in germination at an inter-population level were assessed for G. parviflora. Seed storability in a conventional seedbank was tested. Floral phenology was assessed.

Germination of untreated and seed coat removed seeds were 0 ± 0.0% and 67 ± 5.5% respectively. Seed germination varied between 21.9 ± 1.8 and 66.6 ± 5.5% at an inter-population level. Seeds buried in soil for 6 months showed 11.7 ± 0.8% germination without any treatment. All seeds buried for 12 months were non-viable. Drying seeds from 11.4 ± 0.19% to 5.79 ± 0.17% moisture content resulted in 40% less germination. Visual observation of floral attributes confirmed the presence of orange-coloured pollen grains for 3.5 ± 0.48 days from floral opening. The stigmatic surface became shiny 3.5 ± 0.21 days after floral opening.

Seeds of G. parviflora demonstrate physiological dormancy; treatments that remove seed coat resistance against embryo growth enable germination. Local environmental conditions may explain the inter-population variation in germination. Seeds are short-lived in soil and ex situ seedbank conditions. In soil, seeds release dormancy at the end of first winter, so seeds are available to germinate the following spring/summer with high rainfall. Floral phenology assessment indicated protandrous sequential hermaphroditism, which may reduce the probability of self-pollination in G. parviflora.

This knowledge supports use of G. parviflora in ecological restoration and horticulture.