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Isoetes baodongii is a diploid species of Isoetaceae distributed in low altitude area, its megaspore ornamentation is similar to tetraploid species I. sinensis. We collected leaf material of I. baodongii and sequenced it for low depth whole genome sequence, then, a complete chloroplast genome of I. baodongii was assembled and annotated. This chloroplast genome has a circular structure of 145,494 bp in length with a GC content of 38.0%, comprising a large single copy (LSC) region of 91,860 bp, a pair of inverted repeat (IR) regions of 13,207 bp each, and a small single copy (SSC) region of 27,220 bp. 136 genes were annotated, including 84 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. A maximum likelihood phylogeny tree was reconstructed after the sequences alignment, the result showed that I. baodongii formed a sister clade to the one clustered by I. sinensis, I. taiwanensis and I. orientalis. Although the chloroplast genome structure of I. baodongii is extremely similar to other species distributed in China, a well-supported phylogenetic relationship was reconstructed here, these results may provide new messages for further studies on phylogeny and evolution of vascular plant on the earth.

Cryptic species are commonly misidentified because of high morphological similarities to other species. One group of plants that may harbor large numbers of cryptic species is the quillworts (Isoëtes spp.), an ancient aquatic plant lineage. Although over 350 species of Isoëtes have been reported globally, only ten species have been recorded in China. The aim of this study is to better understand Isoëtes species diversity in China. For this purpose, we systematically explored the phylogeny and evolution of Isoëtes using complete chloroplast genome (plastome) data, spore morphology, chromosome number, genetic structure, and haplotypes of almost all Chinese Isoëtes populations. We identified three ploidy levels of Isoëtes in China—diploid (2n = 22), tetraploid (2n = 44), and hexaploid (2n = 66). We also found four megaspore and microspore ornamentation types in diploids, six in tetraploids, and three in hexaploids. Phylogenetic analyses confirmed that I. hypsophila as the ancestral group of the genus and revealed that Isoëtes diploids, tetraploids, and hexaploids do not form monophyletic clades. Most individual species possess a single genetic structure; however, several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data. All 36 samples shared 22 haplotypes. Divergence time analysis showed that I. hypsophila diverged in the early Eocene (∼48.05 Ma), and most other Isoëtes species diverged 3–20 Ma. Additionally, different species of Isoëtes were found to inhabit different water systems and environments along the Yangtze River. These findings provide new insights into the relationships among Isoëtes species in China, where highly similar morphologic populations may harbor many cryptic species.

Isoetes orientalis is an endangered hexaploidy species of Isoetaceae in China and the complete chloroplast genome of this species has not been reported. In the present study, a complete chloroplast genome of Isoetes orientalis (Isoetaceae) was assembled and annotated. This chloroplast genome has a circular structure of 145,504 bp in length, comprising a pair of inverted repeat (IR) regions of 13,207 bp each, a large single-copy (LSC) region of 91,864 bp, and a small single-copy (SSC) region of 27,226 bp. The chloroplast genome contains 136 genes, including 84 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenetic analysis showed that I. orientalis was closely related to I. sinensis. These results provide additional resources for future studies on Isoetes from China and across the globe.

Isoetes orientalis is an endangered hexaploidy species of Isoetaceae in China and the complete chloroplast genome of this species has not been reported. In the present study, a complete chloroplast genome of Isoetes orientalis (Isoetaceae) was assembled and annotated. This chloroplast genome has a circular structure of 145,504 bp in length, comprising a pair of inverted repeat (IR) regions of 13,207 bp each, a large single-copy (LSC) region of 91,864 bp, and a small single-copy (SSC) region of 27,226 bp. The chloroplast genome contains 136 genes, including 84 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenetic analysis showed that I. orientalis was closely related to I. sinensis. These results provide additional resources for future studies on Isoetes from China and across the globe. [ABSTRACT FROM AUTHOR]

Premise: The isoetalean lineage has a rich fossil record that extends to the Devonian, but the age of the living clade is unclear. Recent results indicate that it is young, from the Cenozoic, whereas earlier work based on less data from a denser taxon sampling yielded Mesozoic median ages. Methods: We analyzed node ages in Isoetes using two genomic data sets (plastome and nuclear ribosomal cistron), three clock models implemented in MrBayes (ILN, WN, and TK02 models), and a conservative approach to calibration. Results: While topological results were consistently resolved in Isoetes estimated crown group ages range from the latest Paleozoic (mid‐Permian) to the Mesozoic depending on data type and clock model. The oldest estimates were retrieved using the autocorrelated TK02 clock model. An (early) Cenozoic age was only obtained under one specific condition (plastome data analyzed with the uncorrelated ILN clock model). That same plastome data set also yielded the oldest (mid‐Permian) age estimate when analyzed with the autocorrelated TK02 clock model. Adding the highly divergent, recently established sister species Isoetes wormaldii to the data set approximately doubled the average median node depth to the Isoetes crown group. Conclusions: There is no consistent support for a Cenozoic origin of the living clade Isoetes. We obtained seemingly well‐founded, yet strongly deviating results depending on data type and clock model. The single most important future improvement is probably to add calibration points, which requires an improved understanding of the isoetalean fossil record or alternative bases for calibration. [ABSTRACT FROM AUTHOR]

Three new species of Isoetes (Isoetaceae) are described from the Democratic Republic of the Congo, Rwanda and Burundi for inclusion in the family treatment for the Flore d'Afrique Centrale. Isoetes hallei sp. nov. is related to I. alstonii and I. schweinfurthii, I. rwandensis sp. nov. to I. abyssinica and I. welwitschii, and I. pichisermollii sp. nov. to I. abyssinica and I. schweinfurthii. The differences between these species are discussed and geographical distribution maps for the new species are presented. The conservation status of the new species is preliminarily assessed. The megaspores of the type specimens of I. abyssinica, I. alstonii, I. schweinfurthii and I. welwitschii were studied using Scanning Electron Microscopy to distinguish the new species from the more similar other ones. Citation: Fischer E. & Lobin W. 2022: The genus Isoetes (Isoetaceae) in Central Africa (Democratic Republic of the Congo, Rwanda, Burundi) with the description of three new species. – Willdenowia 52: 315–334. Version of record first published online on 1 December 2022 ahead of inclusion in December 2022 issue. [ABSTRACT FROM AUTHOR]

The extant plant genus Isoetes (Isoetaceae; lycophyte, quillwort) is important from an evolutionary point of view. Species of this heterosporous genus are small herbs (up to 50 centimeters) and exhibit some morphological, anatomical and embryological features of their Paleozoic arborescent lycopsid ancestors. The species Isoetes pantii produces three kinds of microspores (monolete, alete and trilete) and two types of trilete megaspores in one and the same heterosporangium. We attempt to associate these unusual functional megaspores with various Paleozoic spores described mainly from Devonian barinophytaleans such as Omniastrobus dawsonii, Barinophyton richardsonii, B. citrulliforme and Protobarinophyton pennsylvanicum. These have two kinds of spores in a sporangium and provide the first palynological evidence of heterospory at 405 Ma. The germination of microspores and megaspores and production of gametophytes within the heterosporangia of I. pantii corresponds with that of some of its Paleozoic ancestors. Retention of megaspores within heterosporangia and their germination in situ offers evidence that I. pantii exhibits the probable route of evolution of the seed habit. These observations support the hypothesis that a typical heterosporangium was the cradle for the evolution of heterospory. [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY:Inferring the evolution of characters in Isoëtes has been problematic, as these plants are morphologically conservative and yet highly variable and homoplasious within that conserved base morphology. However, molecular phylogenies have given us a valuable tool for testing hypotheses of character evolution within the genus, such as the hypothesis of ongoing morphological reductions. METHODS:We examined the reduction in lobe number on the underground trunk, or corm, by combining the most recent molecular phylogeny with morphological descriptions gathered from the literature and observations of living specimens. Ancestral character states were inferred using nonstationary evolutionary models, reversible-jump MCMC, and Bayesian model averaging. KEY RESULTS:Our results support the hypothesis of a directional reduction in lobe number in Isoëtes, with the best-supported model of character evolution being one of irreversible reduction. Furthermore, the most probable ancestral corm lobe number of extant Isoëtes is three, and a reduction to two lobes has occurred at least six times. CONCLUSIONS:From our results, we can infer that corm lobation, like many other traits in Isoëtes, shows a degree of homoplasy, and yet also shows ongoing evolutionary reduction.

Abstract The quillwort Isoëtes cangae is a critically endangered species occurring in a single lake in Serra dos Carajás, Eastern Amazon. Low genetic diversity and small effective population sizes (Ne) are expected for narrow endemic species (NES). Conservation biology studies centered in a single species show some limitations, but they are still useful considering the limited time and resources available for protection of species at risk of extinction. Here, we evaluated the genetic diversity, population structure, Ne, and minimum viable population (MVP) of I. cangae to provide information for effective conservation programs. Our analyses were based on 55 individuals collected from the Amendoim Lake and 35,638 neutral SNPs. Our results indicated a single panmictic population, moderate levels of genetic diversity, and Ne in the order of thousands, contrasting the expected for NES. Negative FIS values were also found, suggesting that I. cangae is not under risk of inbreeding depression. Our findings imply that I. cangae contains enough genetic diversity to ensure evolutionary potential and that all individuals should be treated as one demographic unit. These results provide essential information to optimize ex situ conservation efforts and genetic diversity monitoring, which are currently applied to guide I. cangae conservation plans.

A steady increase in the number of lycophyte taxa discovered in Manitoba over the last 20 years prompted a determination of which species should be included in an updated provincial list. Collections made throughout the province since 2008 and a critical examination of over 1000 herbarium specimens enabled a substantive review and update of Manitoba's lycophyte flora. It now comprises 22 taxa: 14 species and two hybrid clubmosses (Lycopodiaceae), three spikemosses (Selaginellaceae), and two species and one hybrid quillwort (Isoetaceae). Thirteen of the 21 species are designated to be of conservation concern, with NatureServe ranks of Critically Imperilled (S1; three), Imperilled (S2; two), or Vulnerable (S3; nine). Based on verified specimens, we describe the abundance and habitats, and summarize recent changes in nomenclature and systematics for all Manitoba lycophyte taxa. [ABSTRACT FROM AUTHOR]

Isoetes baodongii is a diploid species of Isoetaceae distributed in low altitude area, its megaspore ornamentation is similar to tetraploid species I. sinensis . We collected leaf material of I. baodongii and sequenced it for low depth whole genome sequence, then, a complete chloroplast genome of I. baodongii was assembled and annotated. This chloroplast genome has a circular structure of 145,494 bp in length with a GC content of 38.0%, comprising a large single copy (LSC) region of 91,860 bp, a pair of inverted repeat (IR) regions of 13,207 bp each, and a small single copy (SSC) region of 27,220 bp. 136 genes were annotated, including 84 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. A maximum likelihood phylogeny tree was reconstructed after the sequences alignment, the result showed that I. baodongii formed a sister clade to the one clustered by I. sinensis , I. taiwanensis and I. orientalis . Although the chloroplast genome structure of I. baodongii is extremely similar to other species distributed in China, a well-supported phylogenetic relationship was reconstructed here, these results may provide new messages for further studies on phylogeny and evolution of vascular plant on the earth., Competing Interests: No potential conflict of interest was reported by the authors., (© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The quillwort Isoëtes cangae is a critically endangered species occurring in a single lake in Serra dos Carajás, Eastern Amazon. Low genetic diversity and small effective population sizes (Ne) are expected for narrow endemic species (NES). Conservation biology studies centered in a single species show some limitations, but they are still useful considering the limited time and resources available for protection of species at risk of extinction. Here, we evaluated the genetic diversity, population structure, Ne, and minimum viable population (MVP) of I. cangae to provide information for effective conservation programs. Our analyses were based on 55 individuals collected from the Amendoim Lake and 35,638 neutral SNPs. Our results indicated a single panmictic population, moderate levels of genetic diversity, and Ne in the order of thousands, contrasting the expected for NES. Negative FIS values were also found, suggesting that I. cangae is not under risk of inbreeding depression. Our findings imply that I. cangae contains enough genetic diversity to ensure evolutionary potential and that all individuals should be treated as one demographic unit. These results provide essential information to optimize ex situ conservation efforts and genetic diversity monitoring, which are currently applied to guide I. cangae conservation plans. [ABSTRACT FROM AUTHOR]

Populations of Isoetes velata were studied in order to provide more information on their habitat and distribution in the Western and Northwestern Iberian Peninsula. Habitat together with morphology of megaspores were used as diagnostic features. The form I. velata subsp. velata f. lereschii is considered here as a synonym of I. velata subsp. asturicense and therefore only two taxa remain within the species: I. velata subsp. velata and I. velata subsp. asturicense. Intermediate individuals have been found in the Western Central System. The differentiation within the I. velata group appears to be the result of gradual genetic divergence after isolation. Palaeobotanical data confirm the presence of I. velata subsp. asturicense in Late Glacial lake sediments in northwestern Spain. Cluster classification of the soft-water vegetation with Isoetes velata subsp. asturicense revealed two main groups in the Spanish Central System. A single association, the Sparganio angustifolii-Callitrichetum fontqueri which includes Iberian Atlantic stands of Sparganium angustifolium and Isoetes velata subsp. asturicense, is here recognized. Besides, a variant of the association with Eleocharis acicularis is identified in shallow temporary waters in the Western Sierra de Gredos. [ABSTRACT FROM AUTHOR]

Background and Aims Crassulacean acid metabolism (CAM) is an adaptation to increase water use efficiency in dry environments. Similar biochemical patterns occur in the aquatic lycophyte genus Isoëtes. It has long been assumed and accepted that CAM-like behaviour in these aquatic plants is an adaptation to low daytime carbon levels in aquatic ecosystems, but this has never been directly tested. Methods To test this hypothesis, populations of Isoëtes engelmannii and I. tuckermanii were grown in climate-controlled chambers and starved of atmospheric CO2 during the day while pH was measured for 24 h. Key Results We demonstrate that terrestrial plants exposed to low atmospheric CO2 display diel acidity cycles similar to those in both xerophytic CAM plants and submerged Isoëtes. Conclusions Daytime CO2 starvation induces CAM-like nocturnal acid accumulation in terrestrial Isoëtes , substantiating the hypothesis that carbon starvation is a selective pressure for this physiological behaviour. [ABSTRACT FROM AUTHOR]

Rhizomorphic lycopsids are the land plant group that includes the first giant trees to grow on Earth and extant species in the genus Isoetes. Two mutually exclusive hypotheses account for the evolution of terminal rooting axes called rootlets among the rhizomorphic lycopsids. One hypothesis states that rootlets are true roots, like roots in other lycopsids. The other states that rootlets are modified leaves. Here we test predictions of each hypothesis by investigating gene expression in the leaves and rootlets of Isoetes echinospora. We assembled the de novo transcriptome of axenically cultured I. echinospora. Gene expression signatures of I. echinospora rootlets and leaves were different. Furthermore, gene expression signatures of I. echinospora rootlets were similar to gene expression signatures of true roots of Selaginella moellendorffii and Arabidopsis thaliana. RSL genes which positively regulate cell differentiation in roots were either exclusively or preferentially expressed in the I. echinospora rootlets, S. moellendorffii roots and A. thaliana roots compared to the leaves of each respective species. Taken together, gene expression data from the de-novo transcriptome of I. echinospora are consistent with the hypothesis that Isoetes rootlets are true roots and not modified leaves. [ABSTRACT FROM AUTHOR]

Isoetes amazonica and I. gardneriana were the first two species of the genus to be collected from Brazil. Isoetes amazonica was gathered by Richard Spruce in the Amazon basin near Santarém in the state of Pará in 1850. Isoetes gardneriana was collected by George Gardner in the current Dianópolis in Tocantins State in 1843. Despite being known for a long time by botanists, these species have not been recollected since then, which raised questions about their taxonomic recognition, current distribution ranges and conservation status. Fieldwork efforts led to the rediscovery of I. amazonica and I. gardneriana after 167 years. These collections enrich our understanding of their habitats and morphologies. We provide here re-descriptions for these species. Based on IUCN criteria, Isoetes amazonica and I. gardneriana should be assigned as data deficient (DD) and endangered (EN), respectively. The rediscovery of these species raises hopes that other areas in Amazon and Cerrado biomes harbour I. amazonica and I. gardneriana, respectively. This study will serve as a basis towards the conservation of these species. [ABSTRACT FROM AUTHOR]

Umkomasiaceans are the most commonly recorded components of Gondwanan Triassic floras but they are not represented subsequently in that region. Their diversity appears to have substantially declined prior to the Rhaetian. Lower and Middle Jurassic floras in Australia and elsewhere in Gondwana are strikingly different from those of the Triassic, comprising ferns, lycopods, conifers, cycads, and bennettitaleans. The fern Cladophlebis Brongniart 1849 emend. Seward 1894 dominated coal-forming paludal environments during the Middle Jurassic in Queensland and it is one of the most commonly preserved plants in the Eastern Gondwanan Jurassic. Ginkgoaleans were present in Eastern Gondwana until near the end-Triassic but were absent below ca 60°S palaeolatitude during the Early and Middle Jurassic.

In this study, mating system, genetic diversity, and genetic structure of the endangered endemic aquatic Isoetes yunguiensis in China was investigated using ISSR markers. The results of ISSR analyses showed that the estimate of multilocus outcrossing rate (tm) was high at species level (tm = 0.955), indicating that diploid I. yunguiensis is a predominant outcrossing species. Nine selected ISSR primers used in the study amplified 66 reproducible bands, 41 of which were polymorphic among 37 individuals. High level of genetic diversity was detected at the species level (PPB = 62.12%), whereas, relatively low genetic diversity existed within populations (PPB = 39.39%). Analysis of molecular variance (AMOVA) revealed that 31.99% of the genetic variation was attributable to differences between populations and the rest (68.01%) to variability within populationsof I. yunguiensis. Value of Fst (0.320) indicated that genetic differentiation between populations also was significant. These results showed that I. yunguiensis predominantly favors crossing, and has a high level of genetic diversity and highly significant genetic variation between and within populations. Gene flow (Nm) among populations is equal to 1.177. High outcrossing rates may be responsible for the high levels of genetic diversity observed in the I. yunguiensis population. To maintain the current level of genetic diversity for this species, we recommend increasing in situ conservation sites. [ABSTRACT FROM AUTHOR]

To investigate the molecular response of ancient plants to heavy metal stress and to explore the feature of DNA methylation in endangered plants after exposure to heavy metals, the Isoetes sinensis, an endangered plant, was stressed with three different concentrations of two heavy metals lead (Pb) and cadmium (Cd), respectively. Then the degrees and the patterns of DNA methylation in the leaves were measured on the 14th day using Methylation Sensitive Amplified Polymorphism (MSAP) technique. The results showed that the DNA methylated profile of I. sinensis was affected by Pb and Cd stress. There was no significant difference in the amount of DNA methylation among control check (CK), Pb stress group, and Cd stress group (CK 46.96%, Pb 48.23%, and Cd 48.1%). However, full-methylation level of Pb stress group (28.34%) and Cd stress group (20.25%) was lower than control (33.91%), in contrast, hemi-methylation level Pb stress group (19.89%) and Cd stress group (27.85%) were higher than control (13.04%). The change of patterns from no methylation or hemi-methylation of internal and external cytosines into full-methylation of internal and external cytosines accounted for a large proportion in enhanced methylation aspects. The full-methylation into no methylation or hemi- or full-methylation of internal and external cytosines occupied most of demethylation. The proportion of DNA methylation (including hypermethylation) by both Pb and Cd stresses is nearly equal (39.04% and 39.71%), but the proportion of DNA demethylation by Cd is higher than that by Pb (46.86% than 33.92%). [ABSTRACT FROM AUTHOR]

Highlights • Endangered Isoetes cangae produces large quantities of viable spores per sporangia. • Large number of sporelings emerge from male and female spores in vitro culture. • The megaspore nutrient reserve ensures longstanding sporeling growth. • Sporelings are able to grow in a range of substrates and temperature regimes. • Successful growth and low mortality suggest that I. cangae is a resilient species. Abstract Isoëtes L. is a nearly cosmopolitan rhizomorphic lycopsid genus fundamental to disentangling plant evolution because of its singular position in the Plantae kingdom. A threatened Amazonian species recently described is I. cangae, inhabiting an oligotrophic upland lake over an iron-rich region facing substantial environmental alterations. In this study, we aim to optimize a reproduction protocol that can assist in the conservation efforts of Isoëtes species in tropical areas. We observed an average of 126 megaspores or 318,000 microspores per sporangia in field-collected plants. We obtained an elevated percentage of sporelings (63%) from an in vitro mixed culture of mega- and microspores. In addition, we recovered a large number of sporelings around adult plants after cultivating them over quartzite sand and distilled water. The megaspore nutrient reserve ensured longstanding sporeling growth and development in these environmental conditions. However, the sporeling growth rate increased when they were planted over their original lake sediments or over an organic substrate, with nonsignificant differences between the substrates. An increase in temperature also increased the sporeling growth rate. Together with the very low sporeling mortality, these results suggest that I. cangae is a resilient species able to grow and colonize environments with low trophic characteristics with a range of substrates and temperature regimes. The protocols established in this study could be useful for the ex situ propagation and growth of a large number of sporelings, representing critical steps towards the population rescue and conservation of tropical Isoëtes species. [ABSTRACT FROM AUTHOR]

Within the Lycopodiopsida, Lycopodiaceae is a medium-sized family of lycophytes in New Zealand with five genera and 11 indigenous species, and Isoetaceae is a small family with one genus and two species. Fourteen lectotypes are chosen for basionyms relevant to New Zealand - Isoetes alpina Kirk, Lycopodium australianum Herter, L. billardierei Spring, L. consimile Colenso, L. curvifolium Colenso, L. distans Colenso, L. drummondii Spring, L. lessonianum A.Rich., L. novozealandicum Colenso, L. sanguisorba Spring, L. serpentinum Kunze, L. varium var. gracile Kirk, L. varium var. polaris Kirk, and Phylloglossum drummondii Kunze. No type material has been found for Lycopodium decurrens Colenso, and the type for this remains undesignated. Lectotypes need to be chosen for all names at specific and subspecific rank, for which no holotype was designated by the original author, in order to fix the application of the name concerned. Justification for the choice is provided in each case. This article is a contribution towards clarifying the taxonomic and nomenclatural status of New Zealand plants for the plant names database (Ngā Tipu Aotearoa) and the electronic Flora of New Zealand. [ABSTRACT FROM AUTHOR]

To stabilize the application of some names in the genus Isoetes in the Mediterranean biodiversity hotspot, we studied herbarium specimens and imaged spores with scanning electron microscopy, with special reference to those taxa in the I. longissima and I. histrix groups that were described from France, Algeria and Turkey, and are in need of a taxonomic revision. The following names are lectotypified: I. adspersa, I. boryana, I. delalandei, and I. viollaei. Holotypes of I. perralderiana and I. olympica were ascertained. We conclude that I. boryana (listed in the "Bern Convention" and in the European Union "Habitats" Directive) justifies consideration at species rank, but I. adspersa should be synonymized with I. longissima. Isoetes tenuissima and I. perralderiana are proposed as distinct species pending further studies. In the I. histrix group, we tentatively accept I. delalandei as a species, presenting some observations on "I. histrix f. subinermis" nom. nud. The latter might also represent a distinct species. [ABSTRACT FROM AUTHOR]

The triploid (3x=2n=33) hybrid lycophyte Isoetes echinospora × septentrionalis has had a tangled nomenclatural history, largely due to taxonomic confusion surrounding putative parent I. septentrionalis (I. riparia, p.p.). Lectotypification of potential 19th century names is further complicated by the absence of clearly designated types and a failure of authorities to recognize the existence of Isoetes hybrids at that time. Re-examination of the protologue and lectotype of Isoetes dodgei, the name most recently applied to I. echinospora × septentrionalis, indicates that this indiscriminately employs characteristics of three taxa and cannot be unambiguously applied to any particular taxon. An older name can be applied to the hybrid, however, based on an unequivocal lectotype and a clear protologue. Accordingly, the recombination I. ×robusta (Engelm.) D. F. Brunton, comb. nov., is proposed. [ABSTRACT FROM AUTHOR]

Isoetes are ancient quillworts members of the only genus of the order Isoetales. The genus is slow evolving but is resilient, and widespread worldwide. Two recently described species occur in the Eastern Brazilian Amazon, Isoetes serracarajensis and Isoetes cangae. They are found in the ironstone grasslands known as Canga. While I. serracarajensis is present mostly in seasonal water bodies, I. cangae is known to occur in a single permanent lake at the South mountain range. In this work, we undertake an extensive morphological, physiological and genetic characterization of both species to establish species boundaries and better understand the morphological and genetic features of these two species. Our results indicate that the morphological differentiation of the species is subtle and requires a quantitative assessment of morphological elements of the megaspore for diagnosis. We did not detect differences in microspore output, but morphological peculiarities may establish a reproductive barrier. Additionally, genetic analysis using DNA barcodes and whole chloroplast genomes indicate that although the plants are genetically very similar both approaches provide diagnostic characters. There was no indication of population structuring I. serracarajensis. These results set the basis for a deeper understanding of the evolution of the Isoetes genus. [ABSTRACT FROM AUTHOR]

The genus Isoetes is known for morphological convergence and a relative paucity of useful gross morphological characters for identification. Thus, the chromosome complements of Isoetes spp. are key attributes for species delimitation. Like many other plant lineages, polyploidy and reticulate evolution are important drivers of speciation in Isoetes. In the southeastern US Isoetes flora, polyploidy is common. We used a rapid DNA flow cytometry protocol to generate C values for four diploid, one tetraploid, and one hexaploid Isoetes species and conducted preliminary cytological investigations of two communities of Isoetes. Our work showed noteworthy variation in diploid Isoetes 1C values (1.39 to 3.32), including the smallest 1C value reported for the genus, Isoetes melanopoda ssp. silvatica. The hexaploid species, Isoetes microvela had the highest 1C value (4.21), and the tetraploid species evaluated had an intermediate 1C value (3.37). However, based on the variation in diploid 1C values measured, a simple 2×, 4×, 6× ratio of C values was not apparent for diploids, tetraploids, and hexaploids, respectively. All Isoetes taxa measured had significantly different 1C values and homogenous C values were observed in two communities of Isoetes (n = 24). These results indicate that DNA flow cytometry may prove a useful tool for routine Isoetes species identification, systematic work, and population-level surveys of Isoetes ploidy level. [ABSTRACT FROM AUTHOR]

Abstract: Results of the first documented reintroduction of the endangered endemic quillwort Isoëtes malinverniana are presented 1 year after transplanting. This represents the most complete report of a quillwort translocation globally. A new population of I. malinverniana was established in a protected area in Lombardy (northern Italy) after several years of investigation of the ecology, biology and genetics of this species. The selected site was restored before the trial release in March 2016 of 20 individuals of the target species. Although modelling for the selection of suitable release sites for the target species indicated that the selected site was not suitable for the species, I. malinverniana exhibited a survival of 60% 1 year after reintroduction. This trial indicates that with very rare species, experimental trialling of a few individuals can test the feasibility of translocation at a larger scale. Although the model was constructed using a wide variety of ecological and phenological parameters, it was unreliable because of intrinsically low statistical power, which is a limitation of modelling associated with very rare species. Although mature spores were dispersed in autumn 2016, sporelings have not yet been observed. Ultimately, reintroduction of I. malinverniana will rely on the evidence of self‐recruitment; however, this translocation effort promoted understanding of ecological tolerance and facilitated focused conservation management. For instance, a protocol for in vitro reproduction of the species was successfully developed, resulting in long‐term survival of ex situ collections that exist in two botanical gardens in Pavia and Turin. Considering that many isoëtid species are threatened worldwide, the techniques applied here may have broad applicability to other endangered species. [ABSTRACT FROM AUTHOR]

The pollen record from Lagunas de Mojanda, located at 3748 m a.s.l. (northern Ecuadorian Andes) reflects the vegetation and climate dynamics for the last ca 3400 cal yr BP. Páramo vegetation has been the main vegetation type since the beginning of the record. At Lagunas de Mojanda, from the last ca 3400 to 2200 cal yr BP, grass páramo was well represented mainly by Poaceae (40%) and the occurrence of Valeriana (5%), while montane forest taxa were poorly represented and subpáramo taxa were rare. The vegetation composition suggests cool and humid conditions. Between ca 2200 and ca 1300 cal yr BP, montane rainforest and subpáramo taxa had a higher presence but páramo taxa remained the main vegetation type in the study area, suggesting cool climatic conditions. From ca 1300 to ca 500 cal yr BP, páramo vegetation remained stable, with higher presence of Phlegmariurus and Isoetes, suggesting cool and humid conditions. The last ca 500 cal yr BP generally show lower frequency of montane rainforest and subpáramo taxa. Páramo vegetation reached the highest share, with the presence of Poaceae, Plantago and Ranunculus suggesting a trend of peat bog drying. Fires were present during the whole record, perhaps human-caused, but the study area does not show great disturbance except from ca 1300 to 500 cal yr BP, a period of an evident higher influx of charcoal particles coincidentally with nearby ancient human occupation. [ABSTRACT FROM AUTHOR]

Isoetes nana, a new species from the coastal mountains of southeastern Brazil (Serra de Itatiaia), is described, illustrated and compared to similar species. This species can be distinguished from similar species by a set of characters that include 5-15 small erect leaves reaching only up to 3.5cm long, megaspores rugulate (rarely laevigate or obscurely cristate) and microspores sparsely echinate. We include a key to identify this new species and spore images for all species that are discussed in this study. Isoetes nana is known only from the type locality, where it was reported to occur in small ponds on rocky outcrops at high elevations. We suggest it should be classified as a data deficient species based on the IUCN criteria. [ABSTRACT FROM AUTHOR]

In the present study Isoetes coromandelina ssp. thanensis S.K. Shukla, S.K. Singh, P.K. Shukla, N.K. Dubey, H. Khanam & G.K. Srivastava a micro endemic new subspecies is described from the Than in Rajkot District of Gujarat state in coastal zone of India. Morphologically, the new subspecies is most similar to I. coromandelina ssp. coromandelina but differs in its microspore with levigate surface ornamentation and chromosome number 2n = 22 + 1. Different morphological features of I. coromandelina ssp. thanensis are discussed. Images and a distributional map are also provided. In the present study, we made a correlation between microspore ornamentation and ploidal status at the infra-specific level which helpful in taxonomy of closely related taxa. [ABSTRACT FROM AUTHOR]

This study presents taxonomic treatment of the species of Isoetaceae from Serra dos Carajás, Pará, Brazil. Two species occur in this locality (Isoetes cangae and I. serracarajensis). We provide descriptions, illustrations, images of the mega- and microspores, comments, distribution data and a key for these species as a contribution to the knowledge of the flora of the cangas from this area. [ABSTRACT FROM AUTHOR]

LEAFY COTYLEDON1 (LEC1) is a HAP3 subunit of CCAAT-binding transcription factor. The species in the genus Isoetes L. from China include I. hypsophila, I. yunguiensis, I. sinensis, I. orientalis, and I. taiwenensis. In this study, we initially gathered substantial samples from wide geographic ranges in China. Then we explored the evolutionary characteristics and expression profiles of LEC1 in Isoetes from China. We amplified 57 unique LEC1 nucleotide sequences from 94 individuals. The value of nucleotide diversity was 0.01693 for all samples, and neutrality tests indicated that LEC1 is under purifying negative selection in the evolutionary process. AMOVA analysis revealed that the genetic variation occurred mainly among populations within species. Moreover, the non-synonymous to synonymous substitution rates for 41 unique LEC1 protein sequences further demonstrated the presence of negative selection acting on the species from China to fix amino acid residues. Phylogenetic analyses of nucleotide and protein sequences showed consistently that the trees consisted of two well-supported main clades, and that the haplotypes from H42 to H57 in I. hypsophila were exclusive. In addition, expression profile analysis revealed that LEC1 transcripts accumulated primarily in reproductive organs. Looking at drought tolerance, LEC1 transcripts increased markedly at 24 h after drought treatment and reached a peak at 48 h. RNA accumulation reoccurred at relatively low levels and was slightly elevated at 48 h after rehydration. Altogether, our analyses provide insight into the evolutionary process of LEC1, and our results might promote further studies of functional genes in Isoetes. [ABSTRACT FROM AUTHOR]

Isoëtes butleri Engelm. (Butler’s Quillwort) is a lycopod endemic to the central and southeastern United States. It inhabits sparsely vegetated moist depressions within dolomite prairies that become ephemeral wetlands in the spring. Classified as endangered in portions of its range (Illinois and Kentucky), little is known about the ecology and genetics of I. butleri . In Illinois, the five known populations are disjunct from all other known populations, and there is concern that these populations could be vulnerable to a number of threats, including a lack of suitable microhabitats, displacement by other plant species, accumulation of plant litter, and low genetic diversity and limited gene flow. We evaluated these putative threats by analyzing demographic data collected by Plants of Concern, a citizen-science rare-plant monitoring program; performing experimental litter removals; and assessing population genetic structure. There were no significant differences in soil nutrient availability in topographically similar depressions with and without I. butleri ; however, areas inhabited by I. butleri had lower abundance of woody species and higher abundance of conservative (habitat specialist) species than uninhabited areas. Following experimental litter removal, I. butleri exhibited lower size but higher density and recruitment. We found that all populations had high genetic diversity. However, there was also evidence of high inbreeding, which may be due to spatially fine-scale genetic structure and poor dispersal ability. Our findings suggest that reductions of woody plant growth and accumulated litter—both of which can be achieved through prescribed fire—should be management priorities for I. butleri conservation. [ABSTRACT FROM AUTHOR]

The submerged aquatic freshwater macrophyte Isoetes australis S. Williams grows in rock pools situated in south-western Australia, an environment where dissolved inorganic phosphorus (P i ) availability possibly limits growth. In contrast to the two coexisting aquatic species, Glossostigma drummundii and Crassula natans , I. australis did not form relationships with mycorrhiza. P i uptake kinetics were determined for I. australis in experiments using radioactive 33 P i . Roots had a higher P i affinity (lower K m ) than leaves, but roots also had a lower V max , which is discussed in relation to the low ambient P i concentrations. I. australis showed morphological adaptation which could relate to the low P i environment by having approximately twice as much root tissue as leaf tissue (by dry mass), facilitating access to the higher P pools in the sediment compared with the shallow water column. A short-term translocation experiment revealed high amounts of P i translocation internally in the plant which seemed to go from roots and oldest leaves to younger leaves. As a result of the high root to shoot ratio, high surface area, root uptake kinetics, and sediment P i availability, roots accounted for 87% of plant P i uptake and the green parts of the leaves for about the remaining 13%. As a result the estimated P budget for the rock pools showed that the surface water had a P i turnover of about 1.5 days, whereas the porewater P i pool was renewed about 10 times per day to satisfy the P requirements of I. australis . [ABSTRACT FROM AUTHOR]

Isoetes mississippiensis S.W. Leonard, W.C. Taylor, L.J. Musselman and R.D. Bray (Isoetaceae, Lycopodiophyta) is a new species known from two sites along tributaries of the Pearl River in southern Mississippi. This species is distinguished from other species in the southeastern United States by a combination of character states including a basic diploid (2n=22) chromosome count, laevigate megaspores, and a narrow velum covering less than one-third of the adaxial sporangium wall. [ABSTRACT FROM AUTHOR]