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Wild-type pollen cones in Podocarpaceae are simple and “flower”-like, consisting of numerous non-axillary, hyposporangiate microsporangiophores. Teratological pollen cones of Nageia fleuryi are investigated here. One of the most striking and frequent forms is a compound “inflorescence”-like structure, consisting of numerous lateral pollen cones, here analogised with flowers. Each lateral pollen cone is inserted in the axil of a subtending leaf (pherophyll) and consists of several hyposporangiate microsporangiophores. Thus, the branching pattern in the teratological pollen cones corresponds strictly to the general branching pattern of seed plants. In the context of abnormal microsporangiophores that were previously documented for other coniferous groups, and the evolutionary transition series previously suggested for male reproductive structures in Taxaceae s.l., it seems highly likely that the simple, “flower”-like pollen cones of today´s podocarps are derived from a compound “inflorescence”-like ancestral condition by a simple reduction of lateral pollen cones (flowers) to just a single hyposporangiate microsporangiophore and the loss of all pherophylls within the pollen cone.

Spathe movements and spathe senescence mechanics observed during the pistillate and staminate anthesis phases are described in the genera Aridarum, Burttianthus, Hera, Heteroaridarum, Pursegloveia, Naiadia, Tawaia, and Toga. Floral scents and the originating reproductive structures are described and determined, in particular motility of the staminodes and distribution of stomata on the stamen and appendix.

The characteristics of topsoil phytolith assemblages can reflect the local vegetation and climatic conditions. We collected 53 topsoil samples along an isotherm corresponding to a mean annual temperature (MAT) of 4 °C in Northeast China, 20 samples were from the Daxing'an Mountains (DXAM), 18 samples from the Songnen Plain (SNP), and 15 samples from the Changbai Mountains (CBM). The phytoliths were classified into 13 morphological categories. We observed significant differences between the phytoliths assemblages from the DXAM, SNP, and CBM, and they could be statistically discriminated with a total accuracy of 81.1 %. ELONGATE percentages were more sensitive to MAT than to mean annual precipitation (MAP). There was a significant positive correlation between the percentages of ELONGATE, PTERIDOPHYTE-TYPE, PAPILLATE and MAP; and a significant negative correlation between the percentages of BILOBATE and MAP. We constructed a phytolith index (D/W) based on the common phytolith types, which reflects changes in environmental humidity: D/W = BILOBATE / (BILOBATE + ELONGATE); the higher the value of D/W the drier the environment, and vice versa. In Northeast China, D/W varied from 0.0 to 0.6, with the average of 0.3. D/W < 0.3 corresponded to a relatively humid climate, and D/W > 0.3 corresponded to a relatively dry climate.

The temperature and moisture requirements for reproduction (i.e. seed production and germination) underpin the biogeographical relationships between climate, distribution and population dynamics of plants, particularly narrow range endemic species. We aimed to investigate reproductive outputs and the responses of seeds to temperature and moisture availability across three Banksia arborea populations that are distributed over a narrow range (< 200 km²) of semi-arid habitat on banded ironstone formations of Western Australia. We conducted reproductive trait assessments by quantifying follicles per cone, proportion of viable seed and associated seed mass followed by hydrothermal germination assessments for each population to characterise temperature and water stress tolerance. We found the southern-most population, that receives marginally higher rainfall, had heavier seeds (10 ± 0.02 mg), a cooler optimum temperature (16.1 °C) and wider germination capacity under water stress at 10 °C and 15 °C (Ψ_b50 = -0.66 to -0.87 MPa) compared to the two northern populations (Ψ_b50 = -0.60 to -0.65 MPa). By contrast, both northern populations had slightly warmer optimum temperatures for germination (16.9–17.5 °C) and a higher capacity to germinate under water stress at warmer temperatures of 22.5 °C (Ψ_b50 = -0.43 to -0.56 MPa, compared to -0.29 MPa). Our work highlights that, even within the specific requirements of a narrow range endemic, different populations adapt to marginally different temperature and water stress tolerances. Warming of the southern populations could impact on future recruitment, and conservation action to promote resilient ecosystems are suggested.

Most Psittacanthus (Loranthaceae) mistletoes depend on frugivorous birds for seed dispersal, and the behaviour of seed dispersers strongly influences their spatial distribution. However, the timing of seed germination stages remains poorly studied. In this study, ripe fruits from nine Psittacanthus species, inhabiting contrasting habitats and host tree species, were collected for seed germination experiments, in which ripe fruits had their exocarp manually removed, and squashed seeds were placed and glued with their viscin on wooden rectangle sticks and daily monitored for 150 d under common environmental conditions. The germination process from seed attachment involved stages such as drying of the viscin, seed coat breaking, cotyledon expansion, and production of sticky latex-like exudates. Notably, the breakdown of the seed coat and cotyledon number varied among species. Breakdown of the seed coat did not occur in some species at least until the day the experiment ended (P. sonorae and P. auriculatus) and cotyledon number ranged from two to eight, with highest cotyledon count to date recorded for P. schiedeanus. Germination indices differed among species, with P. schiedeanus exhibiting higher values for germination rate and synchrony. A strong phylogenetic signal was found in fruit length, fruit width and cotyledon number. After accounting for phylogeny, cotyledon number was negatively associated with mean germination time and germination uncertainty, and positively associated with mean germination rate and germination speed coefficient. The other germination indices were not significantly associated with fruit or seed morphological traits or altitude. Interspecific variation in cotyledon number, seed coat characteristics, and in the timing and duration of seed germination stages highlights distinct processes, likely influenced by environmental differences. These findings highlight species-specific germination processes, the impact of cotyledon number on germination speed, and the potential evolutionary significance of specific morphological traits among Psittacanthus species.

The limited geographic distribution of endemic species renders them more susceptible to extinction risks stemming from a myriad of factors. One such factor could be meiotic constraints, which may directly or indirectly impact the reproductive success of the endemic plant species. Thus, comprehensive research on meiotic behaviour is essential for implementing species conservation measures. This study represents the first report on the male meiotic behaviour of Artemisia amygdalina Decne., a critically endangered endemic medicinal plant species of the Kashmir Himalaya. We procured the plant material from three different locations in the Kashmir Himalaya, and the chromosome number of the species from all sites was found to be 2n=18 (x = 9, n = 9), indicating its diploid nature. Various types of chromosomal abnormalities were found in these populations, including stickiness, univalents, out-of-plate bivalents, laggards, bridges, disturbed telophase, micronuclei, abnormal pollen grains formation and seed set formation. The overall percentage of chromosomal abnormalities varied among the populations, from 8.58 % to 25.16 %. Pollen sterility also varied among different populations, with maximum pollen sterility of 23.21 % and a minimum of 5.96 % across populations. The present findings will not only help in updating the chromosome atlas with the addition of a new report on chromosome number but also contribute to the understanding of the reproductive success of A. amygdalina. Further ecological and reproductive studies can facilitate the creation of effective management and conservation strategies for this species.

The encroachment of woody species has been affecting wetlands in the Cerrado biome, Brazil. This process has resulted in changes in plant diversity, soil physicochemical properties, and water availability. This study assessed changes in the taxonomic and functional diversity of plants and soil in Veredas wetlands in process of reduction in water availability and woody plant encroachment. Over a 14-year interval, we quantified taxonomic and plant functional diversity, soil physicochemical properties, groundwater depth, and its relationship with historical soil moisture using remote sensing in veredas. We investigated the effect of increased groundwater depth, woody vegetation cover, and changes in soil properties on species cover and richness. We observed a five to seven-fold increase in woody vegetation cover, accompanied by an increased in the richness of woody species from 21.4 % to 28.9 %. Nevertheless, this was counterbalanced by a 15.8 % to 35.2 % reduction in overall species richness and taxonomic diversity. At the same time, functional diversity decreased, leading to a community with more acquisitive traits. Groundwater depth increased from 20 to 60 cm. Soil properties changed, especially organic matter content, which increased two to 14 times. Changes in species richness and cover were related to increased organic matter and groundwater depth. The surveyed veredas exhibited considerable changes in plant species richness, soil, and hydrological properties, as well as woody vegetation cover, over 14 years. The veredas formed distinct functional composition groups between sampling times. However, only one vereda exhibited a reduction in functional richness, and neither showed temporal functional divergence. Woody encroachments are leading these veredas to an alternative state with a reduced herbaceous diversity, structurally denser, and with more resource-acquisitive plant traits in the community. The Woody encroachment reducing soil water availability, may impact ecosystem services, particularly water provision and biodiversity loss in the Cerrado region.

Plant growth and reproduction patterns may be closely associated with environmental seasonality, but the high diversity of plant strategies has revealed complex phenological patterns. Here, we evaluate the occurrence, duration, and seasonality of vegetative and reproductive phenophases of the Brazilian Chaco vegetation. In addition, we summarize the results of a systematic literature review about the phenology of herbaceous and woody plants in different types of seasonal vegetation in the South American Dry Diagonal. Woody plants have a high intense leaf fall and low leaf flush during the dry season in the Brazilian Chaco, whereas in herbaceous plants these phenophases have more fluctuations. In both types, flowering and fruiting are continuous, not uniform, and mainly concentrate during the rainy season. However, woody species present two intensity peaks independent of rainfall, mean temperature, photoperiod, or soil water availability. In turn, in herbaceous species, flowering and fruiting responded to local climatic variables and photoperiod, presenting a peak of intensity during the rainy season. The rainy season plays an important role in plant growth and reproduction in seasonal climates around the world, mainly due to the energetic demand for plants. Like other vegetation types with seasonal climates, particularly in the South American Dry Diagonal, the Brazilian Chaco presents a wide range of phenological patterns, with generally different patterns between woody and herbaceous species. Community-level phenological studies conducted in areas with a seasonal climate have globally focused only on reproduction in relation to vegetative phenology, mostly ignoring herbaceous flora. Here, we emphasize that the phenological complementarity between the woody and herbaceous components is of great importance in maintaining the availability of resources.

Light, despite being essential for photosynthesis, can become an environmental stressor, since at high incidence it can induce photoinhibition. In tropical regions it is known that invasive C4 grasses maintain higher photosynthetic performance than C3 grasses. That is why we evaluated the dynamics of photosynthetic parameters in different grass species of the Brazilian Savanna (Cerrado), taking into account whether they are native or invasive, and have C3 or C4 photosynthetic metabolism pathway. The native species evaluated were Echinolaena inflexa, Trichanthecium cyanescens (C3) and Loudetiopsis chrysothrix (C4), and the invasive species Melinis minutiflora and Urochloa decumbens (C4). We evaluated chloroplastic pigment content, chlorophyll a fluorescence, leaf gas exchange and photochemical energy partitioning on fully expanded and undamaged mature leaves. Results indicate that leaf gas exchange varied throughout the day for all grass species. The invasive species showed higher CO₂ assimilation rates and water use efficiency and lower values of stomatal conductance than native species; however, all species showed a decrease in potential photosynthetic quantum yield at midday. Regarding chloroplastic pigments, chlorophyll a was the only one that presented a difference between the C3 and C4 plant species, and there was no difference between species in the photochemical energy partitioning. Although they occur at the same place, the species showed different responses even when comparing the same type of photosynthetic metabolism. The C4 native species L. chrysothrix was the one that showed values closer to those obtained for the invasive C4 species and may be an alternative in management strategies.

The challenges arising from environmental stress conditions and the intrinsic limitations of their sessile nature strongly affect plants throughout their life cycle. Evolutionarily, plants have developed mitigation strategies, such as acclimation and phenotypic plasticity, to thrive in diverse environmental conditions. In semi-arid environments, light stress plays an important role in seed germination. The objective of this study was to experimentally assess the variability in the phenotypic expression of germination among genetic families of the cactus Mammillaria carnea obtained from different micro-environments along a light stress gradient. Specifically, we investigated germination under white light and far-red-rich light conditions, aiming to simulate lighting conditions with and without canopy cover. The highest germination percentages were observed under white light conditions. However, within the micro-environments associated with Neltuma laevigata and Parkinsonia praecox, greater phenotypic variability and genetic independence were evident under far-red-rich light compared to direct solar radiation. This suggests that while high light intensity enhances seed germination, it also reduces phenotypic expression variability, potentially resulting in decreased evolutionary adaptability in M. carnea populations in high-light stress environments.