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Lucy E Delaney, Boris Igić
International Journal of Plant Sciences; https://doi.org/10.1086/717329

Abstract:
Premise of research. Surprisingly little is known regarding the phylogenetic distribution and frequency of self-incompatibility (SI) in some of the largest angiosperm families, including the legumes (Fabaceae). The ecological and economic significance of the family has motivated an enormous but scattered output of literature concerning its breeding systems and reproductive biology. Since the last synthesis of this literature, we have gained a clearer understanding of the various mechanisms responsible for SI, but data on their number and phylogenetic distribution remain limited. Methodology. We compiled species-level information on legume breeding systems, pollination syndromes, longevity, stature, stem composition, geographic location, and ploidy. The resulting database contains entries for 1167 unique species across 184 genera, accounting for nearly 5% of the family. Using these data, we assess the phylogenetic distribution and frequency of SI in Fabaceae and evaluate the potential correlation between SI and three other traits: ploidy, stem composition, and longevity. Pivotal results. We estimate that approximately one-fifth of legume species have SI, with the remainder being self-compatible. Appropriate controlled pollinations are available for only a small portion of species in our database, and genetic studies are limited to fewer than 0.5% of the family. Moreover, our survey reveals no convincing evidence that a single SI mechanism operates in Fabaceae. Despite uneven coverage and a sample of ca. 5% of Fabaceae, the results of our phylogenetic analyses strongly suggest that longevity is statistically significantly correlated with breeding systems, while ploidy is not. Conclusions. Our collection reveals a great variety of SI expressions in the family. Compelling evidence indicates that one of the best-studied SI systems—RNase-based SI—is homologous across core eudicots and ancestral to the group. Previous studies surmise that this system may operate in Fabaceae, but this remains an open question. Whatever its genetic causes among legumes, the reduced seed and fruit set after selfing appears to evolve dynamically and exhibit uncommon variation. We highlight the need for empirical work evaluating SI and outline areas where future efforts may provide disproportionate rewards.
International Journal of Plant Sciences; https://doi.org/10.1086/717328

Abstract:
The wood anatomy of fagalean families is summarized. Each family and most genera are wood anatomically distinct and can be distinguished by features such as vessel grouping and arrangement, vessel-ray parenchyma pit type, imperforate element type, ray structure, and axial parenchyma distribution. For each family, we review the published fossil wood record (with particular attention to Cretaceous and Paleogene occurrences) that we consider to be reliably identified on the basis of diagnostic character syndromes, giving insights into their stratigraphic range and former geographic ranges. Fossil woods with characteristics of the Fagaceae (Castaneoideae) occurred as early as the Late Cretaceous (Campanian) of the Northern Hemisphere and were widespread in the Cenozoic. Nothofagaceae wood occurred in the Late Cretaceous and Early Tertiary of Antarctica. Ring-porous Castaneoideae were not common until after the Eocene, reflecting the increase in seasonality that occurred in the Northern Hemisphere at that time. Woods diagnostic of Betulaceae, Juglandaceae, and Myricaceae occurred in the Eocene. With the recognition of Morella Lour. as a genus distinct from Myrica L., we propose two new combinations for fossil woods of Myricaceae. Reliably identified Casuarinaceae wood did not occur until the Miocene. There are no reports of Ticodendraceae fossil wood, although there are reports of fossil woods with its combination of features from the Cretaceous onward, but these are assigned to different families or are of unknown affinities. Most fagalean fossil woods have anatomy similar to that of modern genera, but some Paleogene taxa have combinations of characters not found in present-day genera. We discuss the utility of wood anatomy in assessing phylogenetic relationships within and among families of Fagales, with reference to clades supported by molecular sequence data. Generally, wood anatomical groupings are consistent with recent phylogenetic analyses of the order and of its constituent families. We propose hypotheses about adaptive character evolution in the order based on previously presented phylogenetic relationships inferred from DNA sequence data and the current ecological preferences of individual families.
, Javier Puy, Clare Kohler, Juan E. Malo, Gorka Sancho
International Journal of Plant Sciences; https://doi.org/10.1086/717295

Abstract:
Premise of research. Root traits of annual plants are known to vary across environmentally manipulated conditions in controlled settings. Roots absorb nutrients and water, essential for individual function and survival. Yet how ruderal plant populations respond belowground to spatial and temporal variation in field conditions is largely unknown. The present study examines the natural variation of root traits and survival among populations of the annual Arabidopsis thaliana across gardens along a fertility gradient. Methodology. We established common gardens in field settings and in raised beds in the plant’s native and nonnative ranges using populations of A. thaliana from western/central Spain. Survival through the growing season and root traits were investigated for garden and population influences and for the relationship between survival and root biomass. Pivotal results. We demonstrate differences in survival among gardens, populations, and years. Survival was highest in the higher-fertility gardens in the native and nonnative ranges. We detected plasticity (among gardens and between years) of root length, lateral root production, primary root length, and biomass. Roots were substantially larger when grown in the more fertile gardens, where water and nutrients were consistently available. Yet lateral root production was also high in a low-fertility field garden. We detected substantial among-population variation in root traits in the higher-fertility gardens. Conclusions. This study demonstrates among-population variation in root traits in field gardens and substantial root plasticity measured across locations. Evidence of local adaptation was indicated by native local populations showing the highest survival and root growth in the home native garden. Such differences in survival and root functional trait responses inform how plants respond to dramatic changes in environmental conditions, particularly in novel sites. We advocate for additional studies of belowground traits to further uncover the extent of natural variation in root phenotypic responses in the field.
Maria Tekleva, Mário Miguel Mendes, Jiří Kvaček, Peter K. Endress, James A. Doyle
International Journal of Plant Sciences, Volume 182, pp 817-832; https://doi.org/10.1086/716778

, Maria Iracema B. Loiola, Arlete A. Soares, Alexandra A. Mastroberti, Artur A. Sá, Daniel Rodrigues Nascimento Jr., Wellington Ferreira Silva Filho, Lutz Kunzmann
International Journal of Plant Sciences; https://doi.org/10.1086/717104

Abstract:
Premise of research. Araucariaceae are currently disjunctively distributed over the Southern Hemisphere, dominating only some restricted habitats. In contrast, fossil representatives of this group from both hemispheres have been reported from the Mesozoic. In the Araripe Basin (northeast Brazil), fossil representatives of Araucariaceae mainly come from the Crato Formation (ca. 120 Ma). They comprise very abundant sterile leafy shoots, rare detached ovuliferous complexes, and dispersed pollen. The morphological variety of the conifer remains showing araucarioid affinities indicates more diversity in the group, which requires investigation.Methodology. Anatomical features were observed using microscopic slides under optical microscopy and with direct observation under SEM.Pivotal results. We describe vegetative shoots of Araucaria violetae sp. nov. on the basis of gross morphological and anatomical characters. The whiplike (pen)ultimate branches bear densely packed helically arranged awl-shaped leaves. Overall, the new species resembles foliage shoots of species of the extant section Eutacta. They could be interpreted either as portions of ultimate shoots of plagiotropic branches or as portions of caducous adventitious shoots. Importantly, we identify mucilage cells in the leaf parenchyma.Conclusions. The new species provides strong evidence for species diversity among Araucaria in the Araripe Basin. Mucilage cells possibly contributed to the water-use efficiency of the fossil plant in a presumed regional hot and semiarid climate. This cell type is present in extant species of the genera Araucaria and Wollemia but absent in extant species of Agathis. However, its presence in Emwadea microcarpa, a fossil stem agathioid, suggests that mucilage cells were lost in stem group agathioids. Thus, our study contributes to the understanding of mucilage cell evolution in Araucariaceae.
Rachel G. Reback, Dashrath K. Kapgate, Kenneth Wurdack, Steven R. Manchester
International Journal of Plant Sciences; https://doi.org/10.1086/717691

M. Patrick Griffith, Alan W. Meerow, Michael Calonje, Eliza Gonzalez, Javier Francisco-Ortega
International Journal of Plant Sciences; https://doi.org/10.1086/717657

, Hafiz Maherali
International Journal of Plant Sciences; https://doi.org/10.1086/716783

Abstract:
Premise of research. Root allocation and morphology can be influenced by nutritional symbiosis with arbuscular mycorrhizal (AM) fungi. In the presence of AM fungi, plants could alter root allocation and morphology in ways that increase plant reliance on mycorrhizal-mediated nutrient acquisition services. When colonized by AM fungi, plants may reduce root allocation and produce roots with reduced absorptive surface area (i.e., lower specific root length [SRL], root length per unit of mass) and greater habitat area for AM fungal colonization (i.e., lower root tissue density [RTD], root mass per unit of volume).Methodology. We assessed root plasticity in response to AM fungi in two mycorrhizal-dependent species, Medicago lupulina and M. truncatula. Plants were grown with or without AM fungi at both low and high phosphorus levels. The supplemental phosphorus treatment allowed comparison of AM fungal–inoculated plants with uninoculated plants of a similar size.Pivotal results. Growth of M. lupulina and M. truncatula was stimulated by AM fungi at low phosphorus, but there was no effect of AM fungi on growth at high phosphorus. The root allocation, SRL, and RTD of inoculated plants did not differ from that of uninoculated plants of a similar size in a majority of comparisons. When statistically significant differences were observed, the effects were not consistent with the predictions. For example, the RTD of M. truncatula was higher for AM fungal–inoculated plants than for uninoculated controls of a similar size.Conclusions. The results of our experiments with two Medicago species suggest that plants do not necessarily modify their root systems to reduce absorptive surface area and increase habitat space for fungal colonization in the presence of AM fungi. Therefore, reduced root allocation and the development of roots with lower absorptive surface area may not be necessary for some plant species to obtain mutualistic benefits from nutritional symbiosis with AM fungi.
, L. Černochová, J. Košnar, L. Ekrt
International Journal of Plant Sciences; https://doi.org/10.1086/716782

Abstract:
Premise of research. The gametophytes of ferns are nutritionally independent of the sporophytes and are potentially hermaphroditic. The sexual expression of fern gametophytes is based on environmental cues. To prevent excessive self-fertilization, fern gametophytes employ strategies to increase mating between gametophytes. One of these strategies relies on antheridiogens, pheromones released by older gametophytes and absorbed by younger gametophytes. There are multiple distinct antheridiogen types, some of which are poorly understood and in need of further examination. A still-unresolved antheridiogen type was described in Asplenium ruta-muraria.Methodology. We employed cultivation experiments using spores of 12 fern species to assess the extent and uniqueness of the antheridiogen released by A. ruta-muraria. We tested antheridiogen interactions between representatives of three well-established antheridiogen types and A. ruta-muraria to assess their uniqueness. Furthermore, the effect of potentially antheridiogen-releasing gametophytes of A. ruta-muraria on multiple Asplenium species was examined. Germination in darkness in response to antheridiogens was also tested.Pivotal results. The younger gametophytes of A. ruta-muraria did not respond to the presence of older conspecific gametophytes in a way that could be attributed to antheridiogens. No antheridiogen interactions between A. ruta-muraria and any other species were observed. Nevertheless, the exudates of older A. ruta-muraria gametophytes may affect the development of younger conspecific and interspecific gametophytes.Conclusions. On the basis of its interaction with representatives of known antheridiogen types and the lack of germination in darkness, we conclude that our sample of A. ruta-muraria does not use antheridiogens. This discrepancy between our experiment and the initial publication describing antheridiogens in A. ruta-muraria may have been caused by intraspecific genetic variability within the species. The studied individual of A. ruta-muraria may be able to affect the growth of other gametophytes by other means, possibly via allelopathy, although this aspect of gametophyte interaction is poorly understood.
, Alfredo Ortega-Rubio, Neftalí Gutiérrez-Rivera, Pedro P. Garcillán
International Journal of Plant Sciences, Volume 182, pp 695-711; https://doi.org/10.1086/715637

Abstract:
Premise of research. Brahea edulis is an endangered palm endemic to the oceanic island of Guadalupe, Mexico, with a small population of just about 4000 individuals; it was chronically grazed by goats for about two centuries. The evolutionary specificities of insular biotas provide unique scenarios for studying the roles of geography, demography, and climate in driving population divergence. A comprehensive comparison between insular and mainland sister species contributes to a much better understanding of the species-specific responses to the ecological drivers of diversity, divergence, and speciation.Methodology. Here we used a comparative approach coupled with genomic (genotyping by sequencing; single-nucleotide polymorphisms) data to analyze samples from island and mainland Brahea palm species and elucidate their diversity, population divergence, and demographic history.Pivotal results. Genetic diversity analyses revealed higher diversity in insular palms compared with their mainland sister species. Genetic relationships among palm individuals on Guadalupe Island resulted in two strongly diverged clusters that reflected their geographic distributions. Divergence among B. edulis populations was mostly driven by the joint effect of low migration and the climatic heterogeneity of the island’s conditions. Using approximate Bayesian analysis, we further evaluated the demographic history of B. edulis. We found the genetic signatures of demographic fluctuations, inferring an effective population size (Ne) reduction that occurred in the late Quaternary and relatively low current Ne.Conclusions. These findings contribute to the ever-growing body of evidence that low genetic diversity in island populations cannot always be generalized. Besides, genetic diversity and differentiation on islands are more likely to be species specific and are strongly influenced by population size and historical factors such as the time since the population was established, ecological characteristics of the island, and anthropogenic impact. Our results also represent groundwork for future conservation and restoration programs for this endangered insular palm species.
, Ruth A. Stockey, Garland R. Upchurch, Mary L. Berbee
International Journal of Plant Sciences, Volume 182, pp 712-729; https://doi.org/10.1086/715635

Abstract:
Premise of research. Mesozoic to Cenozoic fungi forming scutella, shield-like coverings of sporulating tissue on leaf surfaces, offer insights into the diversification of filamentous ascomycetes. We found a new fungal sporocarp type consisting of radiate scutella growing from the stomata of leaves of a conifer in a survey of dispersed plant cuticles from the Lower Cretaceous of Virginia. Here, we interpret the new morphotype and compare it with other fossil groups and with extant taxa.Methodology. We isolated fragments of conifer cuticles colonized by the fungus from macerated clays of the Potomac Group, lower Zone 1 (Aptian, 125–113 Ma), and studied them using light microscopy. We analyzed the anatomy of scutella of living taxa and compared the fossils with extant taxa producing either rhizothyria, asexual sporocarps that release spores from below the outer edge of the scutellum, or thyriothecia, sporocarps that release spores through dorsal cracks or an ostiole.Pivotal results. Stomatothyrium placocentrum gen. et sp. nov. has a radial arrangement of scutellum hyphae, characteristic of extant and fossil thyriothecial species in Dothideomycetes (Ascomycota). The scutella develop cracks on the dorsal surface that may show the dehiscence mechanism. Unusually for dehiscence in Dothideomycetes, the cracks follow the scutellum circumference rather than its radius. Each scutellum arises from a host plant stoma, appearing first as a hyphal columella that broadens into a flat scutellum disk on the leaf surface. The morphotype is common, and we found more than 63 specimens at different developmental stages on cuticle fragments.Conclusions. Its unique morphology suggests that S. placocentrum gen. et sp. nov. represents a now extinct group of leaf-dwelling Dothideomycetes that formed thyriothecia. This discovery contributes to our understanding of the range of character combinations of early epiphyllous Ascomycota.
Linda Zhang,
International Journal of Plant Sciences, Volume 182, pp 663-681; https://doi.org/10.1086/715638

Abstract:
Premise of research. Fused or connate leaves are a well-known phenomenon observed across a limited number of angiosperm clades, and no study has attempted to examine this form of fusion from an evolutionary, morphometric, or functional perspective. We examined leaf fusion in honeysuckles, specifically the Periclymenum clade (∼22 species) of Lonicera (Caprifoliaceae, Dipsacales), which exhibits variation in leaf shape, degree of fusion, and the position of fused leaves. As fused leaves co-occurred with reproductive structures, evolutionary correlations between leaf fusion and inflorescence architecture were also examined.Methodology. Variation of leaf fusion was assessed using elliptical Fourier analysis, and multiple individuals of 19 of the 22 species of Periclymenum were sampled. As fused leaves occurred only on reproductive shoots, a suite of inflorescence characters were also studied. A phylogeny for Periclymenum was reconstructed using published sequence data, and this tree was used for ancestral character state reconstructions and correlation analyses.Pivotal results. Leaves directly subtending inflorescences of Periclymenum were free or fused but were rarely partially fused. Fused leaves were ancestral to Periclymenum and were lost in parallel. Leaf fusion was not correlated with inflorescence architecture features, yet inflorescence architecture has become more complex among Periclymenum species.Conclusions. While free leaves are the ancestral condition in the Dipsacales, fused leaves have been gained at least three times and lost at least twice. Given the proximity of fused leaves to reproductive structures, particularly in Lonicera, fused leaves may play a role in protection or in the discovery of flowers and fruits by pollinators and seed dispersers, respectively.
Prabha Amarasinghe, Phuc Pham, Robert Douglas Stone, Nico Cellinese
International Journal of Plant Sciences, Volume 182, pp 682-694; https://doi.org/10.1086/715636

Abstract:
Premise of research. Evergreen forests in eastern South Africa have high biodiversity but are limited in extent and have a highly fragmented distribution. Populations of forest plants are thus geographically isolated, and fine-scale evolutionary studies of these lineages might yield important insights into the history and assembly of the forests themselves. A prior study showed that, despite their morphological diversity, three South African Memecylon taxa in Melastomataceae (Memecylon natalense, M. bachmannii, and M. australissimum) had almost identical nuclear ribosomal spacer sequences. Our study investigates phylogenetic relationships within this clade using multiple samples collected across populations and a next-generation phylogenomic approach.Methodology. We used 87 low-copy nuclear (LCN) loci to examine relationships among these taxa using both concatenated and coalescent methods. We further used LCN loci to estimate phylogenetic networks and single-nucleotide polymorphisms (SNPs) derived from LCN genes for STRUCTURE analysis of South African Memecylon populations. Finally, we employed two approaches (flow cytometry and SNPs) to infer the ploidy levels of these three taxa.Pivotal results. Our investigations showed discordance among gene trees and the species tree and low statistical support for relationships, indicating that species monophyly cannot be recovered from this phylogenomic analysis. Phylogenetic networks and population structures showed that the South African Memecylon clade may be affected by gene flow and reticulate evolution. Flow cytometry and SNP-based estimations provided evidence for polyploidy within this group.Conclusions. We found no evidence of monophyly for species within the South African Memecylon clade, which we infer to be the consequence of reticulation and recent and rapid evolution. More cytological studies and genomic data are needed to elucidate the evolutionary history of this group. Additionally, our study identifies priority populations for conservation within the South African Memecylon clade.
, Félix Forest, Duane Fernandes Lima, Margareth F. Sales, Thais Nogales Vasconcelos, Vanessa G. Staggemeier, Eve Lucas
International Journal of Plant Sciences; https://doi.org/10.1086/715639

Abstract:
Premise of research. Myrcia s.l. is the largest exclusively Neotropical genus of Myrtaceae, comprising about 800 species. This large genus is divided into 10 clades, most of these recently published as sections. One section, Myrcia sect. Myrcia, has 114 species distributed from Mexico to Uruguay, with species diversity centers in the Atlantic Forest, Amazon, and Cerrado. This section includes one of the most difficult to circumscribe species of the Neotropical flora, Myrcia splendens, with the same distribution as the genus and currently with almost 170 synonyms. Phylogenetic relationships and biogeographic patterns in Myrcia sect. Myrcia are examined for the first time using molecular data.Methodology. Phylogenetic inference is based on maximum likelihood and Bayesian analysis of internal transcribed spacer (nuclear), ndhF, psbA-trnH, trnL-trnF, and trnQ-rps16 (plastid) sequences obtained by sequencing a morphologically and geographically representative sample. Phylogenetic relationships, divergence time estimates, and biogeographic patterns are investigated using BEAST and BioGeoBEARS.Pivotal results. Results show that Myrcia sect. Myrcia is monophyletic as morphologically circumscribed. Internal relationships indicate morphologically distinct lineages, but the widespread and taxonomically unruly M. splendens emerges as polyphyletic. Lineages from Central America and the Amazon are sister to multiple dispersals to disparate biomes and subsequent colonization of the Cerrado. Further field and laboratory studies are necessary to understand the extreme morphological plasticity of this section, with a particular focus on improving taxonomic delimitations in M. splendens.Conclusions. This article represents the largest sample of Myrcia sect. Myrcia examined to date. The results presented here demonstrate the monophyly of the section and confirm the nonmonophyly of the widespread M. splendens, with multiple accessions emerging in independent clades from different biomes. The mean estimated age for Myrcia sect. Myrcia is 22.4 mya, and the four clades of focus in this article are estimated to have originated in the Miocene.
Lavanya Challagundla, Lisa E. Wallace
International Journal of Plant Sciences, Volume 182, pp 609-619; https://doi.org/10.1086/715504

Abstract:
Premise of research. Numerous biotic and abiotic factors can contribute to local selection and lead to geographic structure and genetic divergence between populations. The southwestern United States contains many distinctive plant communities, ranging from woodlands to desert scrub, that are shaped by species adapting to local variation in elevation, precipitation, seasonality, and soils. Given this variation, species occurring across diverse habitats are expected to harbor high genetic diversity and exhibit significant genetic differences associated with environmental variation.Methodology. Here, we studied the genetic divergence of populations of Xanthisma gracile (Asteraceae) across Arizona using amplified fragment length polymorphisms and evaluated associations between genetic structure, geographic distance between populations, and variation in climatic factors. This species occurs in desert grasslands at low altitudes as well as in open pine forests at intermediate altitudes and exhibits phenotypic variation in plant height, leaf shape and pubescence, and floral traits.Pivotal results. We detected significant genetic structure across populations and found that a population from arid central Arizona is much more genetically distant than samples from northern and southern Arizona that occur in more mesic habitats. We also detected evidence for selection on numerous loci associated with variation in temperature and precipitation.Conclusions. Major changes have occurred across the Southwest since the Last Glacial Maximum, and genetic divergence in X. gracile across Arizona likely reflects selection for survival in climatically diverse habitats.
, Marcelo R. Pace, Veronica Angyalossy
International Journal of Plant Sciences, Volume 182, pp 620-637; https://doi.org/10.1086/715505

Abstract:
Premise of research. The alternative patterns of secondary growth (vascular cambial variants) in stems of Nyctaginaceae are outstanding and have been widely investigated since the late nineteenth century. However, there are controversial interpretations in the literature regarding the existence of either one or two types of cambial variants in this family (successive cambia vs. interxylary phloem). We aim to explore the anatomical diversity of stems in Nyctaginaceae to document the real nature of the cambial variant present in most species of the family.Methodology. We analyzed 60 species, focusing on 18 species from 12 genera, for developmental studies. Anatomical and ontogenetic features were characterized from images produced by standard plant techniques for macro- and microscopic analyses.Pivotal results. Our analyses reveal that most species of Nyctaginaceae present stems with polycyclic eusteles, which later develop a single cambium that produces secondary xylem and secondary phloem at unequal rates around the stem circumference. This unusual activity results in the absence of a regular cylinder of secondary vascular tissues and in the formation of secondary phloem strands (surrounded by variable amounts of sheathing axial parenchyma) embedded within the secondary xylem. In cross section, adult stems can exhibit different tissue arrangements (i.e., phloem islands/strands, patches, or concentric bands) that result from differences in rates of production of phloem and associated sheathing axial parenchyma forming the strands. The cambial variant in these stems is described as interxylary phloem, as similarly observed in other eudicot lineages.Conclusions. Our examination of the stem development of Nyctaginaceae confirms the presence of interxylary phloem, which has been overlooked in the family as most previous studies have reiterated descriptions of successive cambia as the common cambial variant within the family. These findings emphasize the importance of developmental studies encompassing a representative number of genera to further our understanding of stem macromorphologies and to highlight the complexity and diversity of stem architectures in Nyctaginaceae.
Cédric Del Rio, Teng-Xiang Wang, Xiao-Ting Xu, Romain Sabroux, Teresa E. V. Spicer, Jia Liu, Pei-Rong Chen, Fei-Xiang Wu, Zhe-Kun Zhou, Tao Su
International Journal of Plant Sciences, Volume 182, pp 638-648; https://doi.org/10.1086/715507

Rachel S. Jabaily, Brad Oberle, Emma W. Fetterly, M. Shane Heschel, Brian J. Sidoti, Erin N. Bodine
International Journal of Plant Sciences, Volume 182, pp 577-590; https://doi.org/10.1086/715484

Vivi Vajda, Milda Pucetaite, Margret Steinthorsdottir
International Journal of Plant Sciences, Volume 182, pp 649-662; https://doi.org/10.1086/715506

Maiten A. Lafuente Diaz, Georgina M. Del Fueyo, José A. D’Angelo, Martín A. Carrizo
International Journal of Plant Sciences, Volume 182, pp 508-522; https://doi.org/10.1086/714283

Brigitte Meyer-Berthaud, Anne-Laure Decombeix, Romain Blanchard
International Journal of Plant Sciences, Volume 182, pp 418-429; https://doi.org/10.1086/714350

, Patrick S. Herendeen, Fabiany Herrera, Niiden Ichinnorov, Peter R. Crane, Gongle Shi
International Journal of Plant Sciences, Volume 182, pp 490-507; https://doi.org/10.1086/714281

Abstract:
Premise of research. The extinct conifer genus Schizolepidopsis is characterized by deeply bilobed ovuliferous scales bearing two adaxial seeds. Although it is frequently placed in Pinaceae, the evidence for a close relationship with the family is mixed. Resolving the affinities of Schizolepidopsis has important implications for the age of Pinaceae because putative reports of the genus extend into the Late Permian. We describe a new species, Schizolepidopsis ediae sp. nov., based on specimens from the Lower Cretaceous of Mongolia and Inner Mongolia, China, that represent the first anatomically preserved occurrences of Schizolepidopsis.Methodology. Specimens were studied using light microscopy, cellulose acetate peels, and X-ray micro–computed tomography. To test relationships between Schizolepidopsis and Pinaceae, we performed conifer-wide phylogenetic analyses that included 10 previously described fossil conifers using DNA sequence data and a new morphological matrix of ovulate reproductive characters. Analyses were performed using Bayesian total evidence and parsimony backbone approaches.Pivotal results. Schizolepidopsis ediae possesses key characters of Pinaceae, including those related to pollination biology. Most analyses placed S. ediae in crown group Pinaceae (abietoid clade), with all other Schizolepidopsis species forming a grade along the Pinaceae stem. Uncertainty in the data indicates that stem group affinities of S. ediae are also possible.Conclusions. Schizolepidopsis ediae provides the first conclusive evidence linking Schizolepidopsis with extant Pinaceae. The phylogenetic relationships between extant Pinaceae and Schizolepidopsis suggest that seed wings evolved along the Pinaceae stem and not with the crown group and that, in combination with developmental genetic evidence, the simple ovuliferous scales of Pinaceae likely evolved from bilobed ovuliferous scales like those of Schizolepidopsis. More broadly, this study provides evidence of a Mesozoic Pinaceae stem group that might extend into the Paleozoic, helping to reconcile the ancient stem divergence of Pinaceae with its relatively recent crown age.
Mónica R. Carvalho, Fabiany Herrera, Sebastián Gómez, Camila Martínez, Carlos Jaramillo
International Journal of Plant Sciences, Volume 182, pp 401-412; https://doi.org/10.1086/714053

Jill S. Miller, Kimberly Greenberg, Derek Schneider, Rachel A. Levin
International Journal of Plant Sciences, Volume 182, pp 356-376; https://doi.org/10.1086/713915

Angela J. McDonnell, Cheyenne L. Moore, Scott Schuette, Christopher T. Martine
International Journal of Plant Sciences, Volume 182, pp 344-355; https://doi.org/10.1086/713917

International Journal of Plant Sciences, Volume 182, pp 413-413; https://doi.org/10.1086/713916

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