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Fern gametophytes are an often-overlooked part of field studies on ferns due to the challenge of finding material and the difficulty of identifying wild-collected plants. Most existing gametophyte descriptions are derived from lab-reared plants and while it is thought that many of the morphological features are similar under both conditions, we still have a poor understanding of in situ morphology for most taxa. The goal of this work was to document a set of morphological observations from the gametophytes of six different species collected in situ. We discovered identifiable gametophyte populations of Elaphoglossum latifolium, Hymenophyllum myriocarpoum, Lomariopsis maxonii, Polypodium dulce, Polytaenium cajenense, and Sticherus bifidus during the 2022 OTS Tropical Ferns and Lycophytes course in Costa Rica. Gametophytes were collected in the field, observed, and photographed using stereo and compound microscopy. This work represents the first detailed description for these species' gametophytes from field collections and offers insights into their natural morphology. [ABSTRACT FROM AUTHOR]

The coming decades are predicated to bring widespread shifts in local, regional, and global climatic patterns. Currently there is limited understanding of how ferns will respond to these changes and few studies have attempted to model shifts in fern distribution in response to climate change. In this paper, we present a series of these models using the country of New Zealand as our study system. Ferns are notably abundant in New Zealand and play important ecological roles in early succession, canopy biology, and understory dynamics. Here we describe how fern distributions have changed since the Last Glacial Maximum to the present and predict how they will change with anthropogenic climate change – assuming no measures are taken to reduce carbon emissions. To do this, we used MaxEnt species distribution modelling with publicly available data from gbif.org and worldclim.org to predict the past, present, and future distributions of 107 New Zealand fern species. The present study demonstrates that ferns in New Zealand have and will continue to expand their ranges and migrate southward and upslope. Despite the predicted general increased range size as a result of climate change, our models predict that the majority (52%) of many species' current suitable habitats may be climatically unsuitable in 50 years, including the ecologically important group: tree ferns. Additionally, fern communities are predicted to undergo drastic shifts in composition, which may be detrimental to overall ecosystem functioning in New Zealand. [ABSTRACT FROM AUTHOR]

Climate change is expected to increase temperature and temporal precipitation variability leading to higher evapotranspiration and more frequent and severe droughts. While advancements are being made in our understanding of how plants will respond to these changes, gaps remain in our knowledge of species-specific drought response. This is especially true among herbaceous plant communities, including ferns and other seed-free vascular plants. Previous hydraulic work on ferns has almost exclusively concentrated on the leaves, with very little information on the rhizome, which is surprising given that the rhizome is the long-lived perennial organ (making it more costly and important in species survival). Only recently have rhizome hydraulics been explored in the context of drought stress. Similar to observations in many woody trees, fern leaves tend to desiccate and hydraulically disconnect before the perennial stem experiences significant levels of drought-induced embolism, suggesting strong vulnerability segmentation. These findings have significant implications for fern survival during drought. In this review we expand on these observations, integrating information from previous work on plant hydraulics and ecophysiology, to understand the implications of vulnerability segmentation on the response of ferns to future climate change. [ABSTRACT FROM AUTHOR]

We report the case of a phosphaturic mesenchymal tumor of the ankle; an extremely rare lesion that causes osteomalacia via paraneoplastic renal phosphate wasting. A 41-year-old man was referred to plastic surgery with a swelling over the anterior ankle, which had been increasing in size for 1 year. Focused ultrasound assessment was inconclusive, but excision biopsy demonstrated features in keeping with a phosphaturic mesenchymal tumor. Evidence of tumor-induced osteomalacia was subsequently identified on review of historical biochemistry. The patient was followed-up for 1 year with normalization of serum phosphate. In this case report, we present a discussion of the differential diagnosis for foot and ankle soft tissue lesions, and a review of the literature regarding the diagnosis and management of these tumors. Accurate identification of any soft tissue lesion on clinical examination alone is extremely challenging and excision biopsy should be considered in cases of diagnostic uncertainty. [ABSTRACT FROM AUTHOR]

Plants are characterized by their marked plasticity and ability to alter their functional biology to partition ecological niches. However, there are limits to functional trait exploration especially in complex and stressful habitats. Highly specialized traits may control a species ability to explore within and across habitats. Such may be especially true of epiphytes, whose array of unique traits may constrain their ability to cross establish in epiphytic and terrestrial habitats. In the case of ferns, there are few reported examples of species that can grow across these habitats with regularity. However, this study reports and explores species that exhibit great ecological flexibility growing across a wide range of habitats and growth forms. Specifically, we examine species that grow as 1) terrestrially rooted and epiphytic individuals, 2) nest and non-nest-forming epiphytes; and nest-forming terrestrially rooted individuals, and 3) species that grow as terrestrial, epiphytic, and epipetric individuals. We use natural abundance foliar stable isotope ratios (SIR) of N15 and C13, and %N, to explore intraspecific variation in mineral nutrition and water relations across and within niches. Our results reveal the 1) unreported ability of some species to grow across the epiphytic/terrestrial divide, 2) surprising ability of some species to explore these habitats with little to no shift in functional traits; 3) a potentially new function for the nest in nest-forming epiphytes. Finally, our work highlights the need to consider intraspecific trait variation more carefully when studying ferns that occur across a wide range of habitats. [ABSTRACT FROM AUTHOR]

The article discusses the discovery of the American hart's-tongue fern, a rare species primarily found in the Great Lakes region, in a lava tube in New Mexico. The fern population in the lava tube is thriving and protected within a national monument. This discovery challenges our understanding of how ferns establish in dry regions and raises questions about the taxonomic affinities of these populations. Further research is needed to explore these findings. [Extracted from the article]

* Background and Aims Organisms often balance among reproduction, growth and survival. When these processes are in competition, selection may act to drive functional dimorphism. Unlike seed plants, ferns use their foliar surfaces for reproduction and carbon fixation. Across species, ferns exhibit a gradient of fertile-sterile dimorphy: from the production of highly reduced fertile fronds (holodimorphic) to no reduction (monomorphic) in laminar area between fronds. Here the physiological impacts of fertile-sterile dimorphy were investigated through a series of observational and experimental field manipulations. * Methods Temporal shifts in photosynthesis, respiration and percent nitrogen (%N) were examined to evaluate changes in physiological behaviour over the growing season of two species of fern of similar ecological niche, yet of different degrees of fertile-sterile frond dimorphism: Osmundastrum cinnamomeum (holodimorphic) and Osmunda regalis (hemidimorphic). These data are combined with experimental fertile and sterile frond removal to evaluate relative costs of reproduction in both species. Finally, labelled δ13C gas was used to follow carbon allocation across the growing season. * Key Results The data demonstrate that reproductive structures in the holodimorphic O. cinnamomeum come at more significant carbon and nitrogen costs relative to those in the hemidimorphic O. regalis. Excision experiments demonstrate that investment in fertile fronds strongly impacted future allocation to reproduction in the holodimorphic species but had a lesser effect on the hemidimorphic species. The labelling experiments showed that fixed carbon is translocated to the rhizomes only, but at different times in the two species. Investment in underground resources probably allows these plants to manage the costs of reproduction associated with increased dimorphy. * Conclusions Fertile-sterile dimorphy has evolved multiple times in ferns in spite of the apparent physiological costs associated with a reduction in photosynthetically active tissues. These apparent costs may be offset by an increase in potential spore dispersal distance and/or increased spore production. The phenomenon may further influence species ecology as dimorphic taxa often occupy resource-rich environments. [ABSTRACT FROM AUTHOR]

Homosporous vascular plants are typically depicted as extreme inbreeders, with bisexual gametophytes that produce strictly homozygous sporophytes. This view is promulgated in textbook life cycles despite ample evidence that natural populations of most species regularly outcross. We review research on a variety of mechanisms, including genetic load, asynchronous production of eggs and sperm, and pheromonal control of gamete production, that actively promote heterozygosity in ferns and lycophytes. Evolution of the land plants cannot be reconstructed without accurate depictions of the unique life cycle that has helped make ferns the second most diverse lineage of vascular plants on Earth. With revised illustrations and definitions, we provide scientists, educators, and students with a contemporary understanding of fern and lycophyte reproduction, revealing them as evolutionarily dynamic and exploiting a wide range of mating systems. [ABSTRACT FROM AUTHOR]

Ferns are some of the oldest vascular plants in existence and they are the second most diverse lineage of tracheophytes next to angiosperms. Recent efforts to understand fern success have focused on the physiological capacity and stress tolerance of both the sporophyte and the gametophyte generations. In this review, we examine these insights through the lens of plant water relations, focusing primarily on the form and function of xylem tissue in the sporophyte, as well as the tolerance to and recovery from drought and desiccation stress in both stages of the fern life cycle. The absence of secondary xylem in ferns is compensated by selection for efficient primary xylem composed of large, closely arranged tracheids with permeable pit membranes. Protection from drought-induced hydraulic failure appears to arise from a combination of pit membrane traits and the arrangement of vascular bundles. Features such as tracheid-based xylem and variously sized megaphylls are shared between ferns and more derived lineages, and offer an opportunity to compare convergent and divergent hydraulic strategies critical to the success of xylem-bearing plants. Fern gametophytes show a high degree of desiccation tolerance but new evidence shows that morphological attributes in the gametophytes may facilitate water retention, though little work has addressed the ecological significance of this variation. We conclude with an emergent hypothesis that selection acted on the physiology of both the sporophyte and gametophyte generations in a synchronous manner that is consistent with selection for drought tolerance in the epiphytic niche, and the increasingly diverse habitats of the mid to late Cenozoic. [ABSTRACT FROM AUTHOR]