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This special issue honors Dr. Vicki Ann Funk (November 26, 1947–October 22, 2019), who passed away after a battle with an aggressive cancer. She was a botanist at the Smithsonian Institution during her career from 1981 to 2019 after a postdoctoral year at the New York Botanical Garden. Vicki was an inspirational evolutionary biologist and a champion for collections-based systematics and biogeography. She had broad influence on the way we perform our collections-based systematics today, especially with the development of phylogenetic systematics in botany in the early 1980s and throughout her career. Vicki was one of the most active, enthusiastic, and passionate professional botanists of our time. She combined these qualities with a quick mind and glowing wit, always with new ideas or opinions that she was eager to share with anyone who would listen and be willing to enter an engaging dialogue. During her distinguished career, Vicki achieved preeminence in the fields of phylogenetic methods, systematics, biogeography, and biodiversity conservation. She devoted a significant part of her career to mentoring the next generation of botanists and working with groups to tackle larger areas of research, especially Compositae systematics, phylogenetics, and biogeography. [ABSTRACT FROM AUTHOR]

Premise of research. From a purely palynological perspective, lowest Danian fern-dominated assemblages of the Williston Basin (North Dakota and southwestern Saskatchewan) and the Raton Basin (northeastern New Mexico and southeastern Colorado) appear indistinguishable, although this perspective has yet to be corroborated by macrofloral studies across this same region. No ferns have been collected from the lowest Danian barren series of the Raton Formation in more than a century, and this section remains sparsely sampled. Methodology. New collections of fossil ferns from the basal portion of the barren series or informal middle member of the Raton Formation, which directly overlies the K/Pg boundary, are compared with contemporaneous assemblages in other North American depositional basins. Pivotal results. Dennastra sorimarginata McIver and Basinger (Dennstaedtiaceae Lotsy) and Woodwardia arctica (Heer) Brown (Blechnaceae Newman) that produce Cyathidites diaphana (Wilson and Webster) Nichols and JL Brown and Laevigatosporites haardtii (Potonié and Venitz) Thomson and Pflug, respectively, are recognized as characteristic ferns in the basal portion of the barren series, in addition to Osmunda macrophylla Penhallow. Conclusions. In accordance with palynological perspectives, lowest Danian fern macrofossil assemblages from the Raton Basin support the concept of a geographically widespread "postdisaster" pteridophyte flora represented predominantly by Dennstaedtiaceae and Blechnaceae, with other minor components of more northern assemblages. The enigmatic hypothesis of a landscape dominated by anemiaceous or schizaeaceous ferns is rejected on the basis of this new evidence, which suggests that Cyathidites diaphana –producing dennstaedtiaceous ferns were the K/Pg boundary "disaster taxon" and among those that flourished in the Raton Basin. [ABSTRACT FROM AUTHOR]

An interview is presented with Chris Strand, director of CHARLES F. Montgomery. Topics discussed include the book "The Natural History of Carolina, Florida, and the Bahama Islands" by Mark Catesby; similarities between Mark Catesby and H. F. du Pont; and the concept of rarity as applied to botany, gardens, and horticulture in both the past and present.

The International Journal of Plant Sciences (IJPS) is a journal that supports plant scientists at all stages of their career. It offers affordable open-access publication options and has a history of providing accessible summaries of plant science papers. In line with this, the journal has introduced a new series called "Primers in the Plant Sciences," which are peer-reviewed, citable, and accessible introductions to specific topics in plant science. The primers aim to serve various audiences, including instructors, researchers, graduate students, and plant science educators. The current issue of IJPS contains two primers on secondary pollen presentation and direct phytochemical defenses against herbivores. The development of the primer series is motivated by a desire to increase access to scientific information, encourage interdisciplinary research and learning, and combat plant awareness disparity. The journal welcomes primer series proposals from researchers and educators. [Extracted from the article]

Premise of research. Devonian assemblages from South China have become an important source of data on the rise of land plants and are thus supplementary to a scenario historically based on fossils from the Laurussian region and Siberia. Less attention has been given to assemblages from Sichuan and their paleogeographic significance than to those from Yunnan and adjacent provinces in China. Methodology. Descriptions of plants, including lycopsids, with enations are based on coalified compression fossils lacking anatomy, and they complete our analyses of the Sichuan Lower Devonian assemblages. Compiled species lists for the entire assemblage are compared with those from coeval assemblages from South China using simple statistical methods (including Simpson's coefficient of similarity). Pivotal results. Studies confirm the presence of endemic lycophytes and emphasize the importance of detailed study of Drepanophycus spinaeformis before any conclusions about its global occurrence can be made. Conclusions. Statistical analysis of the whole flora confirms that the assemblage from Sichuan is distinct from that at Yunnan, but distinguishing two further subregions in South China requires descriptions of further taxa. [ABSTRACT FROM AUTHOR]

An extinct kind of asymmetric samara occurs in the Eocene of Colorado, Utah, and Wyoming. The distinctive winged fruits were attributed to Anacardiaceae by Roland Brown in the 1920s and 1930s and were placed in the fossil genus Anacardites. However, that generic name, based on leaves from the Oligocene of France described a century earlier by Saporta, is inappropriate for these fruits. The samaras, which were not previously described in detail, are pedicellate, with a scar of hypogynous perianth and disk, and are nonschizocarpic, with an elliptical single-seeded endocarp and a lateral wing supplied with arching subparallel venation. We recognize these fruits as an extinct genus, Barkleya gen. nov. Although morphologically unique, the fruits share some characters in common with samaroid fruits of subfamily Anacardioideae, including Amphipterygium , Faguetia , Loxopterygium , Orthopterygium , and Schinopsis. We also provide an emended diagnosis for Rhus nigricans foliage and speculate, on the basis of co-occurrence and shared familial relationships, that the fruits of Barkleya schinoloxus (RW Brown) comb. nov. were produced by the same plant, which was a common element of the early to middle Eocene Green River flora. [ABSTRACT FROM AUTHOR]

Premise of research. How vegetation adapts to environmental changes is one of the most important questions in plant science. Temperature and precipitation are considered the main climatic drivers of morphological variations in vegetation. Several studies have demonstrated that leaf morphology varies reliably with increasing latitude, and this is mostly attributed to changes in temperature and precipitation patterns. The morphological responses of plants to temperature and rainfall regimes in arid lands are still scarcely known and understood. We analyze the morphological variation in leaf traits (size and shape) as well as the internode distance in the species Larrea divaricata and their relationship with bioclimatic variables along a latitudinal gradient in central western Argentina. Methodology. We combined a set of morphological features and bioclimatic indexes using multivariate statistics and detected six relevant regions with clear differences in both plant morphology and climatic variables. Pivotal results. The largest foliar areas were located in sites with higher seasonal precipitation. Leaf shape was influenced by temperature, and the internode distances were larger under semihumid conditions. Conclusions. The plant traits of L. divaricata were influenced by the latitudinal gradient and the predominant climate conditions of each recognized region. The study of foliar morphology allowed us to identify environmental factors that potentially influenced morphological responses in the studied species. As a preliminary stage in our research, our contribution attempts to recognize woody plant adaptations to climate influence. Other environmental variables must be included in future work for a more complete analysis. [ABSTRACT FROM AUTHOR]

Research has shown that there has often been overlap between the humanities and the sciences. This essay brings to the fore a prominent borderline case in cultural history, where the mix of disciplines that could contribute to its study became an issue of debate. It examines the attempts made by botanists throughout the nineteenth century, culminating around 1900, to call into question the monopoly of the humanities on cultural history. Botanists argued that botanical objects, such as the original forms of ancient grains, were important historical sources, and the renowned Georg Schweinfurth even advocated a new concept of "culture" that prioritized the sciences. The essay argues that this development is part of the period's discourse on the origins of human civilization, which included more and less productive encounters between the botanical study of the migration and development of plants over time and the study of human history. [ABSTRACT FROM AUTHOR]

The International Journal of Plant Sciences has released a new issue featuring Primers in the Plant Sciences, a series of curated reviews that cover foundational topics and serve as useful references for scientists at all career stages. The issue includes articles on topics such as the evolutionary ecology of direct phytochemical defense against herbivores and pollen transfer within flowers. The journal also includes illustrations and photographs to enhance the understanding of the topics discussed. [Extracted from the article]

Premise of research. Jurassic localities of fossil flora in the Irkutsk Region (East Siberia) are rich in reproductive remains of gymnosperms with in situ pollen. Our aim was to understand the morphology of pollen grains from conifer cones of Schidolepium gracile in the context of the botanical affinity of their parent plant. Methodology. Pollen grains were studied in transmitted light as well as with SEM and TEM. Pivotal results. The pollen grains demonstrate an unusual combination of morphological and ultrastructural traits. In pollen masses, they appear circular, asaccate, and flattened in a polar position. Detached monads show a polar and equatorial position equally often; the outlines are rounded, oval, and irregular. An equatorial-distal saccus was revealed. A small trilete scar is occasionally present. The surface is fossulate. The ectexine is formed by structural elements that fused with each other by their lateral surfaces partially or completely. The element is a solid elongated cylinder with a rounded external end and narrowing internal end/ends. The elements are arranged along their length, perpendicular to the pollen surface. The endexine is more electron dense than the ectexine, and it is prominent and appears homogeneous. We revealed variations in pollen morphology that we consider preservational, although the existence of two species of Schidolepium is not excluded. One of the cones was contaminated by pollen grains of the Cycadopites type; electron microscopical data proved their ginkgoalean affinity. Conclusions. The exine ultrastructure excludes an araucariaceous affinity, in spite of a relatively close general morphology. Certain similarities to Cerebropollenites were found in the exine ultrastructure, but it possesses a distal aperture and proximal saccus-like extensions. Although the pollen cones have something in common with the Taxodiaceae and Voltziales, the palynological data do not support this relationship. The plant apparently represents an early member of an evolutionary line within conifers. [ABSTRACT FROM AUTHOR]

Premise of research. Resolving the time and patterns of origination of the Isoetales that thrived in the wet habitats of the late Paleozoic and have extant representatives in the genus Isoetes requires a better understanding of their early members and precursors. Recent studies conducted for a large part in South China acknowledged the diversification of Middle to Late Devonian taxa that possessed isoetalean traits and either were closely related to the Isoetales or occupied a basal position within this plant order. Recent investigations of Late Devonian floras from Australia show that this area, on the northeastern edge of Gondwana, also yields taxa with combinations of characters unknown elsewhere. Methodology. The anatomy and external morphology of an anatomically preserved fragment of a lycopsid axis from the Famennian locality of Barraba, in New South Wales, are described. The new specimen is compared to lycopsid taxa on the basis of anatomically preserved specimens ranging from the Middle Devonian to the Late Carboniferous. Pivotal results. The Barraba specimen shows a new combination of characters consisting of a medullated protostele, three-zoned cortex with a wide middle cortex, homogeneous primary outer cortex, presumably deciduous leaves, and slightly protuberant widely spaced leaf bases. Leaf bases show a single large parichnos and are covered adaxially by a thick translucent layer. The specimen is interpreted as the distal branch of a new arborescent taxon, Lycaugea edieae. Taxa with the closest morphoanatomical characters, such as Wexfordia hookense , belong to the Isoetales and are found in deposits of Europe and the eastern United States. Conclusions. Lycaugea edieae is the third lycopsid taxon described from Barraba, which, to date, has yielded a majority of spore-producing plants. It increases the diversity of the early Isoetales around the Devonian-Carboniferous boundary. The Barraba flora is more similar to the contemporaneous flora in southern Laurussia than to that in China. [ABSTRACT FROM AUTHOR]

Premise of research. The Miocene Punta Basílica Beds (northeast of Tierra del Fuego, Patagonia, Argentina) preserved a flora rich in insect herbivory traces. Here we document its insect damage and compare it with three Miocene floras from northwestern Argentina (low-latitude San José and Palo Pintado) and New Zealand (high-latitude Hindon Maar). In addition, comparisons are established for insect damage observed on Miocene Nothofagus in the Punta Basílica flora and the New Zealand Hindon Maar, Double Hill, and Kaikorai floras. Methodology. Plant-insect interactions were photographed and determined for 209 fossil leaves collected at the Punta Basílica locality. Leaves were censused for the presence/absence of functional feeding types. Pivotal results. Six functional feeding groups and 26 damage types (DTs) were recognized: hole (seven DTs) and margin (five DTs) feeding, skeletonization (six DTs), piercing and sucking (two DTs), mining (three DTs), and galling (three DTs). Nothofagus spp. are the most affected members of the paleoflora. Both of the low-latitude paleofloras compared have lower percentages of damaged leaves than the high-latitude ones; hole and margin feeding, mining, and skeletonization are recognized at all floras. Hole and margin feeding and skeletonization are recognized on Nothofagus leaves and are the most common functional feeding groups; hole feeding on Nothofagus is more prominent at Hindon Maar and Kaikorai than at Double Hill and Punta Basilíca. Additionally, Nothofagus specimens from Hindon Maar and Punta Basílica have evidence of mining, whereas galling is observed only on the New Zealand leaves. The Punta Basílica Nothofagus specimens are the only ones with piercing and sucking. Conclusions. Southernmost Miocene records of leaf herbivory worldwide and the first record from Argentine Patagonia are rich and comprise several functional feeding groups also observed in other Miocene paleofloras from the Southern Hemisphere. Clearly, multiple biotic and abiotic factors explain differences in the intensity of folivory. This report evidences the need for additional studies on herbivory at high-latitude floras. [ABSTRACT FROM AUTHOR]

Premise of research. The Triassic is considered a pivotal time for the radiation of modern conifer families. In this article, we describe the conifers from the Fossillagerstätte Kühwiesenkopf/Monte Prà della Vacca, emending already known taxa and proposing a new species (Voltzia edithae sp. nov.). Moreover, we provide a picture of the chronostratigraphic and geographic distribution of the Middle Triassic conifer shoots of Europe. Methodology. The macromorphology and cuticles of the vegetative conifer organs are described, and the stratigraphic and geographic distribution pattern of the Middle Triassic conifer shoots in European is evidenced. Pivotal results. Six different conifer species are identified among the conifer shoots of the Kühwiesenkopf flora. Morphological analyses of our material of Albertia cf. latifolia show that the previously described species A. latifolia , A. elliptica , A. braunii , and A. speciosa probably fall within the natural variability of one species, but this has to be validated by the revision of the original specimens. The occurrence of V. heterophylla in the Kühwiesenkopf flora extends its geographic range to the Alpine Realm. An emended diagnosis is proposed for V. walchiaeformis based on well-preserved specimens, including cuticle fragments. The new species V. edithae sp. nov. shows significant morphological similarities to the late Permian Majonica alpina and the Middle–Late Triassic V. foetterlei. Conclusions. The conifers of the Kühwiesenkopf flora are unique for the Middle Triassic of Europe in their richness and diversity. The conifers are a mixture of typical Early–Middle Triassic taxa (Pelourdea vogesiaca , V. heterophylla , V. recubariensis), Anisian taxa (V. walchiaeformis), and a new species (V. edithae sp. nov.) that is seen as a transitional form sharing morphological characters with both late Permian and Middle–Late Triassic conifers. [ABSTRACT FROM AUTHOR]

The International Journal of Plant Sciences published an article titled "Front Cover" which discusses the research conducted by Valentin-Silva et al. on the effects of temperature variations and water availability on the germination parameters, root growth, and seed traits of Piper umbellatum. The study found that seeds produced during the rainy season had the highest germinability, while those from the dry season produced the most vigorous seedlings. These findings suggest that climate change can have a significant impact on the early stages of plant development, and the responses to these changes can vary depending on the seed production period. [Extracted from the article]

The International Journal of Plant Sciences would like to express their gratitude to the numerous reviewers who dedicated their time to assist in the publication of this volume. The list includes a diverse range of individuals from various backgrounds and expertise, showcasing the collaborative effort in the field of plant sciences. This acknowledgment highlights the importance of peer review in ensuring the quality and accuracy of scientific research. [Extracted from the article]

Premise of research. Climbing plants are important components of modern-day tropical forests and primarily comprise angiosperms, but in Paleozoic tropical forests, pteridosperms were the dominant climbers. Climbing pteridosperms are well known from the Paleozoic floras of Euramerica, while much less is known about climbing pteridosperms from other phytogeographic regions. We document from the earliest Permian Taiyuan Formation of Cathaysia a new genus and species of a small vine preserved in situ and in 3D in a volcanic tuff bed from the Wuda locality. We consider the affinity and ecology of the new plant and evaluate its abundance and distribution in the Wuda forest community. Methodology. Macrofossils were prepared by dégagement, and sharpened needles were used to expose the plant from the overlying sediment. Anatomy was revealed by petrological thin sections. Key features of the plant were observed under scanning electron microscopy. Pivotal results. Only the aerial organs of the plant are known, and they comprise stems up to 4.5 mm in diameter that bear hooked prickles and fronds. Branching is irregular, probably axillary, with buds situated in axils of the stem and fronds. Stems are eustelic with well-developed secondary xylem. Lanceolate and distinctly asymmetric bipinnate fronds arise from the stem in nodes. Fronds show considerable variation in both size and shape, and pinnules are strongly heterophyllous. Large pinnules have relatively long conical pinnule lobes terminated by pads that are adapted for climbing, which we consider to be pinnule climbing adaptations. Epidermal cells on pinnules have large paracytic stomatal apparatuses. Fertile pinnules with well-developed pinnule laminae appear to have borne reproductive organs above lateral veins and between the midvein and the pinnule margin on the lower (abaxial) pinnule surface. Fertile structures are incompletely preserved and appear to represent pollen organs; seeds are unknown. Conclusions. Although its fertile organs are unknown, characters of the new plant are most similar to those of the pteridosperm family Callistophytales and in particular Callistophyton , but it is distinct from existing genera, leading to the erection of Wudaeophyton wangii gen. et sp. nov. Wudaeophyton wangii is reconstructed as a vine climbing on Psaronius marattialean fern associations in the bottom of the tuff bed and on Cordaites gymnosperm associations at the top. We interpret W. wangii to most likely be a member of the Callistophytales, leading us to consider the persistence and evolutionary diversification of Callistophytales in the Cathaysian floras after their regional extirpation in Euramerica, which broadly coincided with the onset of the Permian, and their eventual extinction in the Lopingian (upper Permian) before the end-Permian mass extinction event. [ABSTRACT FROM AUTHOR]

Premise of research. The earliest occurrences of several characteristic late Permian and early Mesozoic plant groups have been described from Euramerican floras of Pennsylvanian and early Permian age. The basinal deposits in which such early representatives occur are generally associated with short-lived drier conditions or with a gradual shift toward a drier climate. In this article, we provide formal descriptions of voltzian conifer fossils (voltzian Voltziales) from a middle Permian flora based on the macromorphological characteristics of ovuliferous cones and isolated dwarf shoots and the epidermal characteristics of broad, parallel-veined leaves. Methodology. The fossils were examined using light and scanning electron microscopy. Pivotal results. The discovery of the three new conifer taxa described here is important for four reasons. First, Pseudovoltzia sapflorensis (Majonicaceae) cones are the oldest-known members of this genus in western Euramerica. Second, the morphology of the ovuliferous dwarf shoot Wantus acaulis is unlike any of the other late Paleozoic or early Mesozoic voltzian conifer taxa and thus represents a new Paleozoic voltzian conifer lineage. Third, the broad, parallel-veined leaves of Johniphyllum multinerve have a macromorphology that is predominantly known from Mesozoic voltzian conifer lineages, but their epidermal features are comparable with those of late Paleozoic conifer taxa. Fourth, the swollen leaf bases of J. multinerve suggest that the leaves were actively abscised, a functional trait that is unusual in Paleozoic conifers. Conclusions. Together, these three new taxa increase both the taxonomic diversity and the morphological disparity among both reproductive and vegetative structures in late Paleozoic voltzian conifers and once more illustrate that structural evolution, innovation, and diversification in this conifer group took place in more extrabasinal environments, where chances of preservation are unlikely. The migration of these conifers to the basinal lowlands, and thus into the window of preservation, seems to have been facilitated by the increasingly drier climate. [ABSTRACT FROM AUTHOR]

Premise of research. Late Permian Voltziales are interpreted to have given rise to most extant conifer families, although their origin and evolutionary relationships are still poorly understood. The Poldarsa Formation (Kichuga Member) of Mutovino (=Isady) in European Russia yielded a diverse Lopingian (upper Permian) flora including some very peculiar compound ovuliferous cones. Methodology. The micromorphologies of eight specimens of dispersed compound ovuliferous cones—some in organic connection with conifer shoot fragments—are described, and their relationships are tested in a phylogenetic analysis. Pivotal results. Mutoviaspermum krassilovii gen. et sp. nov. is characterized by a stout main axis with helically arranged ovuliferous scales protected by coriaceous bracts. The polysperms have a peltate structure with an apical whorl of segments fused only in the basal part near the stalk and with a seed scar on each segment. The anatomical connection between M. krassilovii and Quadrocladus -like leaves provides the basis for reassessing the botanical affinities of these taxa. Conclusions. A morphological phylogenetic analysis supports the placement of Mutoviaspermum as an early-diverging genus within Voltziales, although a precise relationship of this genus with other early conifers remains uncertain. Results of this analysis underline the ambiguous position of Quadrocladus and highlight its complex and poorly understood relationship within the Permian conifers. [ABSTRACT FROM AUTHOR]

Premise of research. A diverse fruit and seed assemblage has been discovered in tuffaceous sandstone molds and casts from a classic paleobotanical locality of probable late Eocene age in Trinity County, East Texas. Application of microcomputed tomography (μ-CT) X-ray scan technology has revealed a previously hidden carpological diversity and extensive evidence of feeding damage by animals. Methodology. Natural molds and casts in sandstone were analyzed through standard light microscopy and μ-CT X-ray scans, which were processed in Avizo, VGStudio, and Meshlab to construct 3-D surfaces or volumes of the molds. These visualizations were compared with equivalent renderings for fruits and seeds of similar modern taxa. Pivotal results. Seven new generic occurrences, including Meliosma (Sabiaceae), Yua (Vitaceae), Engelhardia (Juglandaceae), Turpinia (Staphyleaceae), Nyssa , Mastixia (Nyssaceae), and Symplocos (Symplocaceae), and 15 species, plus several unidentified species, are recognized. Prior identifications to Myristica and Phoenicites are rejected, an emended diagnosis is provided for Nyssa texana , and original material is reillustrated. A new northern extent for the distribution of the mainly Neotropical clade Symplocos sect. Symplocos is established. The flora includes several thermophilic elements and some that are now confined to Asia and/or Malesia. Fruit and seed predation, evident in the overwhelming majority of specimens and taxonomically indiscriminate, serve as a rare and unique snapshot of plant-animal interactions. Conclusions. Although previously suggested to derive from the Catahoula Formation, current mapping suggests that this flora was collected from the Whitsett Formation and is likely of late Eocene age. The flora shows very little overlap with the nearby early Oligocene Huntsville flora. Further study will be necessary to identify the sources of feeding damage, and more samples will need to be collected in order to specifically identify the remaining unnamed material. [ABSTRACT FROM AUTHOR]

Premise of research. Typical plant groups of the late Paleozoic Cathaysian floras from East and Southeast Asia include noeggerathialeans, gigantopterids, and endemic pteridosperms, but also cordaitaleans are abundant peat-forming elements. Even though coal ball floras have allowed whole-plant reconstructions of some cordaites, the classification of Cathaysian cordaitalean foliage still largely relies on macromorphological features. The Lower Shihhotse Formation (Guadalupian; Permian) exposed in the Palougou section in Shanxi, North China, hosts well-preserved macrofloras with abundant, large Cordaites leaves accompanied by typical Cathaysian genera, such as Tingia , Yuania , Cathaysiopteris , and Emplectopteris. Pivotal results. Bulk macerations have yielded abundant, exceptionally well-preserved cordaite cuticles, including the first records of axes, cones, seeds, and complete dwarf-sized leaves. Similarities in diagnostic epidermal features—especially in the characteristic stomatal architecture and arrangement—as well as the presence of in situ pollen grains recovered from cones and seeds allow us to reconstruct these organs into a single whole-plant cordaitalean species. Conclusions. The unique combination of characters enables the erection of a new genus and species, Wangjunia microphylla. The unusual quality of preservation of the various cuticle remains allows detailed comparisons of this new species with other Cathaysian and Euramerican Cordaitales. Wangjunia microphylla may be a representative of a distinctive cordaitalean lineage that inhabited the North China microcontinent from the Late Carboniferous to the middle Permian. [ABSTRACT FROM AUTHOR]

Premise of research. Newly identified fossils attributable to Rhus (Anacardiaceae) from the latest early Eocene flora of Republic, Washington, are recognized. Included are a revision of Rhus malloryi , three new species of Rhus based upon leaflet and rachis morphology, and a group of Rhus leaves showing variation in leaflet morphology, venation, and margin, in part comparable to similar features seen in hybrid angiosperms today. Together, these fossils demonstrate that Rhus was already undergoing diversification in western North America during the latest early Eocene. Methodology. Compression-impression fossils preserved in a lacustrine shale were uncovered from the rock matrix and photographed with light microscopy. Specimens were compared morphologically with fossil and extant material of related plants, and resulting images were processed minimally with Adobe Photoshop. Pivotal results. Fossil Rhus leaves are diverse in the Eocene and demonstrate morphologies characteristic of hybrid leaves in this genus today. Conclusions. This study demonstrates greater systematic diversity than previously known within the genus Rhus in the Okanogan Highlands flora of Republic, Washington. These leaves also provide additional evidence for possible hybridization and other evolutionary processes at play within the sumacs by the latest early Eocene in western North America. [ABSTRACT FROM AUTHOR]

Premise of research. Permineralized peats are prized for hosting three-dimensionally preserved plant remains that provide insights into fossil plant anatomy and the composition of coal-forming ecosystems. A new record of siliceous permineralized peat is documented from a Lopingian-aged (upper Permian) strata from the southern Sydney Basin. It represents the fifth Permian permineralized peat identified from eastern Australia. Methodology. The single permineralized peat block was cut into smaller blocks, and both cellulose acetate peels and standard thin sections were prepared for study using transmitted light microscopy. Quantitative analysis of the peat was carried out using point counts perpendicular to bedding. One block examined using synchrotron X-ray computed tomography (CT) revealed the three-dimensional anatomy of abundant fossil seeds. Pivotal results. The peat contains a plant assemblage dominated by glossopterid leaves, seeds, and axes; although degraded, probable pteridophyte remains represent a significant subsidiary component of the assemblage. A new leaf form (Glossopteris thirroulensis McLoughlin et Mays sp. nov.) and a new type of seed (Illawarraspermum ovatum McLoughlin et Mays gen. et sp. nov.) are described. Leaf-, wood/seed-, and fine detritus-rich organic microfacies with gradational boundaries are evident within the peat. Conclusions. Regular growth rings in the small permineralized axes, together with the occurrence of autumnal mats of glossopterid leaves, signify a strongly seasonal climate. The presence of abundant charcoal in the peat indicates that fire was a significant influence on the high-paleolatitude mire ecosystem. Differentiation of organic microfacies within the peat profile indicates subtle variation in the contribution of plant components to the peat through time. The absence of mineral grains in thin section and CT, together with the presence of authigenic sulfides, indicates accumulation of organic matter in a stagnant mire away from the influence of clastic input. [ABSTRACT FROM AUTHOR]

Abundant silicified fruits formerly attributed to the Euphorbiaceae have been reinvestigated and found to represent Arecaceae. The fruits are from Ghughua near Shapura, in Madhya Pradesh, central India, of probable early Paleocene age. Fruits of Palmocarpon drypeteoides (Mehrotra, Prakash et Bande) comb. nov. are trilocular indehiscent drupes. The distinctive feature of germination pores, one of which is dorsally positioned near the base of each carpel, indicates that these fruits represent palms rather than a dicotyledonous family. Among extant Arecaceae, closest morphological and anatomical similarities are found among South American representatives of subtribe Attaleinae, within tribe Cocoseae, of the subfamily Arecoideae. These fossils indicate an early presence of Attaleinae in the Old World tropics and relatively rapid intercontinental dispersal in view of the hypothesized South American origin of the clade. Palmocarpon drypeteoides, together with three other palm fruit taxa and abundant vegetative remains previously published from the same beds, indicates that palms were diverse, as well as abundant, in the Ghughua flora of India. [ABSTRACT FROM AUTHOR]

Flora of North America: North of Mexico. Volume 10: Magnoliophyta: Proteaceae to Elaeagnaceae Edited by Flora of North America Editorial Committee. [Extracted from the article]

Premise of research. One hundred and one years ago, Thismia americana was discovered in a prairie near Chicago in the United States. This tiny mycoheterotrophic plant was observed at the type locality for a few years but is now considered to be extinct. The occurrence of the mainly tropical genus Thismia in temperate North America remains a mystery, particularly because T. americana's putative most closely related species occurs in Australia and New Zealand. Here we evaluate the affinities of T. americana using morphological data and the relationships of the two other species in Thismia subgen. Thismia sect. Rodwaya with molecular data. Methodology. A 21-character morphological data set of 50 Thismia species was analyzed with parsimony and Bayesian phylogenetic analyses. A data set of eight species of Thismia and allied taxa containing sequence data of the nuclear 18S and mitochondrial atp1 regions was analyzed with maximum likelihood and Bayesian phylogeny inference methods, including a Bayesian relaxed molecular clock analysis. Pivotal results. Morphological data indicate that T. americana is most closely related to the Old World species of Thismia. Nuclear and mitochondrial data suggest that Old World species of Thismia are part of a single clade but also show that the section Rodwaya is not a monophyletic group. Conclusions. The results suggest that T. americana diverged from an Old World ancestor, but the morphological similarity of T. americana to other species in the section Rodwaya may result from the presence of plesiomorphic characters or convergent evolution rather than close phylogenetic affinity. Northern Hemisphere species of Thismia may be more plausible close relatives of T americana. Under the latter scenario, T. americana would be part of an Amphi-Pacific Northern Hemisphere disjunction, a more commonly observed distribution pattern in plants. [ABSTRACT FROM AUTHOR]

Pseudostellaria heterophylla, a cleistogamous species belonging to the Caryophyllaceae, was studied ontogenetically with SEM to investigate floral development in chasmogamous (CH) flowers and cleistogamous (CL) flowers. Comparative ontogenetic studies of this cleistogamous species revealed significant differences between CH and CL flowers. As opposed to other findings for cleistogamous species, the results of this study showed that divergence in the development of the floral forms occurs at inception, not later during organ growth. The floral organ inception in the CH flower is as follows: five sepal primordia are initiated in a helical sequence, 10 stamen primordia are initiated in two whorls (an antesepalous whorl and an antepetalous whorl sequentially), petal primordia are initiated by the division of common stamen-petal primordia, and three carpel primordia are initiated last. The floral organ inception in the CL flower is as follows: four sepal primordia are initiated in two pairs alternatively, two stamen primordia are initiated oppositely, no petal primordia are initiated, and two carpel primordia are initiated last. In comparison with the CH flower , fewer floral organs are initiated in the CL flower . No other reports of cleistogamic differences similar to those observed here for P. heterophylla are to be found in the literature. The reduction pattern in the CL flower is somewhat similar to that observed in the rest of the members of the Caryophyllaceae family. It is concluded that the CL flower is not a developmental modification of the CH flower and that the four sepals of the CL flower may arise as a continuation of bracteole initiation. [ABSTRACT FROM AUTHOR]

Plant fossils recently recovered from the Pride Mountain Formation (Mississippian/Serpukhovian) of northern Alabama include a single type of rooting base preserved as casts and permineralizations, a single stem type preserved as compressions and permineralizations, and compressions of a single type of leaf, sporophyll, and megaspore, suggesting that this was a monospecific assemblage and facilitating whole-plant reconstruction. Permineralized specimens were analyzed by means of cellulose acetate peels, and compressions were analyzed as hand samples with selected macerations. These heterosporous, ligulate, cormose, isoetalean lycopsids are semiherbaceous with frequent variable branching. The lobed base produces forking rootlets and a small amount of secondary xylem. Internal anatomy transitions into external morphology, conforming to known isoetalean lycopsid characters from both compression and permineralized specimens with sufficient variation to suggest that this plant constitutes a new genus and species that should be known as Winslowia tuscumbiana Dunn, Atkinson, Lacefield, and Rischbieter. Reconstructing whole plants is one of the primary goals of paleobotany, and this rare occurrence of permineralized and compression remains representing all the organs of a plant in a monospecific assemblage allows for the reconstruction of this plant from the inside out as a much-branched, cormose Mississippian lycopsid. [ABSTRACT FROM AUTHOR]

We investigated whether the plants of the Galápagos Archipelago and Cocos Island, which are each other's closest neighboring insular systems, show any such sister relationships. Five genera of vascular plants have endemics in both archipelagos, including plants with different life histories and dispersal mechanisms: tree ferns, epiphytes, trees, herbs, and shrubs, with adaptations for dispersal by wind or birds (two genera each) or with no obvious dispersal adaptation (one genus). We obtained molecular phylogenies for these genera to test the hypothesis of phytogeographical links between the islands. The phylogenies for all five genera were not consistent with this hypothesis, but they supported floristic studies in revealing no direct phytogeographical links between the islands. We attribute this lack of floristic affinity primarily to air and ocean circulation patterns that limit dispersal between Galápagos and Cocos and to a low frequency of interisland bird movements. There are also major ecological differences between them, and Cocos Island is quite small, which limits the chance of random dispersal events and subsequent establishment. [ABSTRACT FROM AUTHOR]

During wheat-rye allopolyploidization, the characteristics of the sequences in the bands that appear in both parents and progeny are still unclear. In this study, two different combinations of wheat (Triticum aestivum L.) and rye (Secale cereale L.), including F1 hybrids and the first and second allopolyploid generations, were analyzed by PCR and sequencing using 60 wheat expressed sequence tag (EST)--derived single-sequence repeat markers and EST-derived sequence-tagged site markers. Thirty markers produced the same bands from parental plants, F1 plants, and amphiploids. Seven of the 30 markers amplified identical sequences from wheat and rye parents. Most of these sequences have high similarity between the two parental plants. The variation patterns of sequences in the bands produced by the seven markers were observed. In the F1 hybrids and amphiploids, loss of parental sequences was observed and the frequency of losing rye sequences was higher than that of losing wheat sequences. In addition, a few sequences in these bands exhibited significant differences, indicating that parental sequences changed drastically during allopolyploidization. Therefore, the fact that the parents and progeny contained the same bands should not be regarded as conservation. The results in this study add to the investigations dealing with variation patterns of coding sequences during wheat-rye allopolyploidization. [ABSTRACT FROM AUTHOR]

Populations of the moss Atrichum undulatum contain females, males, and hermaphrodites, and hermaphrodites can have sex organs in close proximity or spatially separated across branches. Here we ask whether differences in gender influence selfing rates or progeny fitness. We used allozyme electrophoresis to measure selfing rates of female and hermaphrodite gametophytes. We measured size and spore number of sporophytes from females and hermaphrodites and germination, survival, and photosynthetic capacity of their gametophytes grown on medium with supplemental nutrients or only with tap water to simulate a harsher environment. Females showed no significant selfing between sibling gametophytes. Significant within-gametophyte selfing was found in hermaphrodites with minimal spatial separation of male and female sex organs. Parental gender did not influence sporophyte size, but sporophytes from females contained slightly more spores. After 6 mo, only progeny from females survived on tap water media. When progeny were transplanted onto tap water media, progeny of females had greater photosynthetic capacity but also higher nonphotochemical quenching than that of hermaphrodites, resulting in realized photosynthetic rates similar to those of hermaphrodites. While the observed fitness differences are small, they suggest that there may be selection on sexual systems in A. undulatum, perhaps through either increased provisioning of resources to progeny by females or gametophytic inbreeding depression following selfing in hermaphrodites. [ABSTRACT FROM AUTHOR]

Although the flower is the unit of sexual reproduction in angiosperms, a plant's reproductive success is determined by its entire floral display. A trade-off between the size and number of flowers produced is an assumption of models of floral display evolution, but this trade-off is often not observed. We tested three hypotheses for why a trade-off between flower size and number is not observed, using 32 populations of Mimulus guttatus and 83 genera from the California flora. We found support for the hypothesis that high variance in resource acquisition masks a trade-off between flower size and number. In contrast, we did not find support for the hypothesis that trade-offs between current and future reproduction mask negative correlations between flower size and number in lineages with a perennial life history. We also did not find support for the hypothesis that negative flower size-number correlations are less likely to be observed in lineages with lower variation in flower number because the correlation between two variables is weaker when the range of values is narrower. Overall, our results support the life history evolution literature in suggesting that high variance in resource acquisition relative to allocation can often explain why traits that are predicted to trade off are instead positively correlated. [ABSTRACT FROM AUTHOR]

Charles Darwin hoped that a large body of working naturalists would embrace evolution after the Origin of Species appeared in late 1859. He was disappointed. His evolutionary ideas at first made painfully little progress in the scientific community. But by 1863 the tide had turned dramatically, and within five years evolution became scientific orthodoxy in Britain. The Origin's reception followed this peculiar trajectory because Darwin had not initially tied its theory to productive original scientific investigation, which left him vulnerable to charges of reckless speculation. The debate changed with his successful application of evolution to original problems, most notably orchid fertilization, the subject of a well-received book in 1862. Most of Darwin's colleagues found the argument of the Origin convincing when they realized that it functioned productively in the day-to-day work of science--and not before. The conceptual force of the Origin, however outwardly persuasive, acquired full scientific legitimacy only when placed "in the harness of daily labour." [ABSTRACT FROM AUTHOR]

The seed cone Telemachus is known from several Triassic localities in Gondwana. New specimens from two localities in Antarctica provide additional information about the type species, Telemachus elongatus, based on details of morphology and anatomy revealed by using a modified transfer technique on the compressed plants. Seed cones of T. elongatus are up to 6.0 cm long and characterized by conspicuous, elongate bracts. A second Antarctic species, described here as Telemachus antarcticus, is segregated, based on a shorter bract and differences in cone size. Newly recognized features of the genus include the shape, size, and disposition of the ovules; vascularization of the ovuliferous complex; and scale and bract histology. As a result of this new information, it is now possible to compare Telemachus with the permineralized Middle Triassic conifer seed cone Parasciadopitys from the Central Transantarctic Mountains. The similarities between the two genera make it possible to relate organs in different preservational modes and to develop a more complete concept for this widely distributed Gondwana conifer. Placing the Telemachus plant within a phylogenetic context makes it possible to evaluate the relationship with other so-called transitional conifers, an informal group that has been interpreted as intermediate between Paleozoic and modern conifers. [ABSTRACT FROM AUTHOR]

Disease epidemiology has rarely been examined in natural plant-pathogen systems exhibiting obligate alteration of host species. We quantified rust infection in populations of jewelweed; its effect on host mating system, potential biotic and abiotic correlates of infection; and spatial patterns within populations. Jewelweed (Impatiens capensis) is a woodland annual that can become infected with the heteroecious rust, Puccinia recondita, whose alternate hosts are often grasses. It produces dimorphic self-pollinated cleistogamous (CL) flowers and open-pollinated chasmogamous (CH) flowers. Infected plants may have fewer resources, so we predicted a decrease in CH flowering relative to that of uninfected plants. Infection occurred early in the growing season and disappeared by midsummer, although plants continued to grow and flower until the frost. We found no clustering of infection within populations. Infection prevalence did not vary among sites in 2005, but one site had more disease in 2004 than in 2005. Rust infection showed negative host density dependence, which is unusual for most pathogens but not unexpected for heterocyclic rusts. Infection decreased host fitness but increased proportional allocation to CH flowering, potentially increasing the production of resistant offspring by susceptible plants. These results indicate that disease varies over time and with host density and can affect host fitness and mating system. [ABSTRACT FROM AUTHOR]

Relatively few studies have investigated plant responses to the combined effects of multiple environmental factors. We studied the responses of canola (Brassica napus) seedlings to combinations of temperatures (22°/18°C and 28°124°C), ultraviolet-B (UVB) radiation levels (S [ambient] and 10 [enhancedj kJ m-2 d-1), and watering regimes (well watered and water stressed). The higher temperature decreased stem diameter, leaf area, individual organ and total-plant dry mass (DM), net CO2 assimilation (AN), water use efficiency (WUE), the chlorophyll (Chi) a-Chl b ratio, and UV-absorbing compounds but increased specific leaf mass (SLM), leaf mass ratio (LMR), shoot-root ratio (SRR), and Chl b. Enhanced UVB reduced leaf number and area, DM accumulation, SLM, LMR, AN, WUE, carotenoids, and Chl a : Chl b but increased leaf area ratio, SRR, and ethylene evolution. Water stress decreased plant growth, leaf moisture, leaf, stem, and total DM, LMR, SRR, and gas exchange but increased photosynthetic pigments, UV-absorbing compounds, epicuticular wax, and ethylene evolution. Many plant parameters were affected by two- and three-way interactions. Main factors and their interactions revealed that water stress has a larger negative influence on plants than the other two factors. We suggest that, under conditions of global climate change, water stress may have a stronger effect on plant performance than UVB radiation. [ABSTRACT FROM AUTHOR]

Understanding the relationships within the Caryophyllaceae has been difficult, in part because of arbitrarily and poorly defined genera and difficulty in determining phylogenetically useful morphological characters. This study represents the most complete phylogenetic analysis of the family to date, with particular focus on the genera and relationships within the large subfamily Alsinoideae, using molecular characters to examine the monophyly of taxa and the validity of the current taxonomy as well as to resolve the obscure origins of divergent taxa such as the endemic Hawaiian Schiedea. Maximum parsimony and maximum likelihood analyses of three chloroplast gene regions (matK, trnL-F, and rps16) from 81 newly sampled and 65 GenBank specimens reveal that several tribes and genera, especially within the Alsinoideae, are not monophyletic. Large genera such as Arenaria and Minuartia are polyphyletic, as are several smaller genera. The phylogenies reveal that the closest relatives to Schiedea are a pair of widespread, largely Arctic taxa, Honckenya peploides and Wilhelmsia physodes. More importantly, the three traditional subfamilies (Alsinoideae, Caryophylloideae, and Paronychioideae) are not reflective of natural groups; we propose abandoning this classification in favor of a new system that recognizes major lineages of the molecular phylogeny at the tribal level. A new tribe, Eremogoneae Rabeler & W.L.Wagner, is described here. [ABSTRACT FROM AUTHOR]

The mycoheterotroph Monotropa hypopitys L. has been used as a model organism for evolutionary ecology studies of nonphotosynthetic plant species. However, the species has perplexed plant biologists for centuries owing to confusion over taxonomic placement of two discrete color forms (red and yellow). The purpose of this study was to characterize the population genetic structure of M. hypopitys using 11 microsatellite markers and to determine levels of genetic differentiation between these two color forms. Results from this analysis demonstrated relatively low to moderate levels of genetic variation across populations in Ohio and Indiana (eastern United States), with levels of variation differing between color forms. Substantial genetic differentiation was detected among populations of the yellow color form and between the red and yellow color forms. Additionally, analyses showed genetic structuring of sympatric and allopatric populations of M. hypopitys by color form, a distinction that may support a taxonomic revision at the subspecific level. This study offers conclusive evidence of genetic divergence among populations and color forms of M. hypopitys, possibly arising from habitat fragmentation and limitations in gene flow associated with a mycoheterotrophic life history. [ABSTRACT FROM AUTHOR]

The genus Cooksonia Lang 1937 includes some of the earliest land plants. Specimens of Cooksonia pertoni Lang 1937 are considered the earliest Eutracheophytes. The definition of the genus is thus central to the delineation of the clade. However, the generic diagnosis is problematic. It is not restrictive enough, and most of the few diagnostic characters are plesiomorphic. Observations on new specimens of Cooksonia paranensis Gerrienne et al. 2001, a species very close to C. pertoni, considered along with a compilation of the Cooksonia literature, allow us to propose more precise diagnostic characters. An allometric study was performed on more than 100 specimens of C. paranensis. This study allows discrimination of true morphological variations from growth stages. The growth habit of Cooksonia is discussed. An emended diagnosis including apomorphic characters is given for the genus, as well as a lectotypification of the genus and the type-species. [ABSTRACT FROM AUTHOR]

An updated data set of 25 fossil floras sampling plant communities from the Early Cretaceous (~123 million years ago) to the Pliocene (~3 million years ago) is reanalyzed to assess the evolution of a latitudinal gradient in seed size during the radiation of angiosperms and the effect of this gradient on estimations of temporal trends in seed size. There is a significant negative correlation between the median seed size of Tertiary floras and their paleolatitude. As in modern floras, average seed size decreased from the equator toward the poles. Results indicate that previous documentations of a striking increase in within-flora seed size around the Cretaceous/Tertiary boundary (66 million years ago) are valid and conservative: the older (Cretaceous) floras sampled communities that in life were closer to the equator, relative to the younger (Tertiary) floras. [ABSTRACT FROM AUTHOR]

The arctic biome is a relatively young ecosystem with ;2300 species of vascular plants. We studied the genus Ranunculus as an example of the origin and evolution of the arctic flora. For this purpose we used molecular phylogenetic and clock analyses based on evaluation of nuclear ITS and chloroplast matK-trnK DNA sequences in 194 taxa of Ranunculus and closely related genera. Taxa occurring in the Arctic arose from seven phylogenetic lineages of Ranunculus and also in the genera Coptidium and Halerpestes. Two clades of Ranunculus are species-rich in the Arctic, i.e., Ranunculus sect. Ranunculus and R. sect. Auricomus (both from R. subg. Ranunculus), but this is due to a number of arctic "microtaxa" morphologically barely separate from R. acris in the former clade and the widely agamospermic species complex of R. auricomus in the latter. Lineages with species adapted to wetlands or aquatic habitats are significant groups represented in the arctic flora (R. subg. Ranunculus sectt. Flammula and Hecatonia/Xanthobatrachium, R. subg. Batrachium, genus Coptidium) but show no clear signs of radiation in the Arctic or the northern boreal zone, except for sectt. Hecatonia/Xanthobatrachium, with R. hyperboreus and R. sceleratus subsp. reptabundus. Astonishingly few of the otherwise numerous lineages of Ranunculus with distributions in the higher mountain systems of Eurasia and North America have acted as ''founding sources'' for the arctic flora. The only clear example is that of the arctic-alpine R. glacialis and the Beringian R. chamissonis from the lineage of subg. R. sectt. Aconitifolii/ Crymodes, although there might be others in sect. Auricomus not recovered in the current molecular data. Lineages that gave rise to arctic taxa diverged from each other from the early Miocene (R. glacialis/ R. chamissonis, Coptidium, lineages in Halerpestes) and continued at an even rate throughout the Tertiary. There are no signs that the intense climate changes of the late Pliocene and the Quaternary substantially accelerated or impeded diversification in Ranunculus. Only the crown group split of R. acris and its relatives is clearly of Quaternary age. A detailed comparison concerning morphology, karyology, and life form excludes fundamental differences between taxa of Ranunculus in the Arctic and their respective closest relatives in regions south of it. Ecological traits, e.g., preferences for dry or moist soils or growth in open and sheltered conditions, also do not differ between arctic and nonarctic taxa. Migration into the Arctic thus started from different phylogenetic lineages and at different times, without development of obvious special traits in the adaptation to arctic environments. This recurrent pattern in Ranunculus differs from that seen in other arctic genera, e.g., Artemisia, in which special traits of adaptation to arctic environments are found. In Ranunculus, the origin of the open arctic biome primarily favored range expansions of taxa/species already adapted to wet habitats in cold areas and depending on rapid dispersal. [ABSTRACT FROM AUTHOR]

The genus Czekanowskia is an important member of the Mesozoic flora and is widespread in the Northern Hemisphere. In China, it is found mostly in Late Triassic and Early and Middle Jurassic sediments of North China. With the exception of a few specimens, all the reports of this genus from China have been based on gross leaf morphology. Abundant Czekanowskia leaves, preserved as compression fossils, were collected from the Middle Jurassic, Zhaogou Formation of Inner Mongolia, China. In this article, two subgenera of Czekanowskia, Harrisella and Vachrameevia, are recognized from Inner Mongolia, China, on the basis of leaf morphology and epidermal characters. Two new species, Czekanowskia chinensis sp. nov. (subg. Harrisella) and Czekanowskia shiguaiensis sp. nov. (subg. Vachrameevia), are described. The occurrence of these species in the Middle Jurassic of Inner Mongolia significantly extends the stratigraphic and geographic distribution of Czekanowskia in the Northern Hemisphere. Analysis of the epidermal characters of material presented here along with consideration of other associated plants of the flora and sedimentology of the plant-bearing strata suggests that the two species described in this report grew in an area with a warm and humid climate in a warm temperate zone. Biostratigraphic correlation of the plant-bearing strata indicates that the specimens described here are Middle Jurassic in age. [ABSTRACT FROM AUTHOR]

Evolutionary relationships in Ephedra are difficult to resolve, mainly because there are few informative characters in investigated loci and long distances to outgroups. We address these problems by using a large data set that includes information from seven plastid and nuclear loci and 204 vascular plants. The deepest divergences in Ephedra are weakly supported and differ by analytical method, but they indicate a basal grade of species distributed in the Mediterranean area. New World species are monophyletic, with a South American clade possibly nested within a North American clade. A mainly Asian clade comprises several well-supported subgroups, of which some are endemic to restricted geographic regions in East or Central Asia; others have a broad distribution that may extend into Europe (E. distachya, E. major) and/or Africa (E. pachyclada-E. somalensis). Ephedra laristanica and E. somalensis are nested within other species, whereas the recognition of E. milleri as a separate species is supported. Our results provide another example of how exceptionally difficult it is to disentangle the early divergences of seed plants. Bayesian analysis strongly supports the "gnetifer" hypothesis, a result rarely found in the literature, but it conflicts with our results from only chloroplast data ("gne-cup") and with results of most maximum parsimony analyses ("Gnetales sister"). [ABSTRACT FROM AUTHOR]

A positive correlation between the sizes of plants and the sizes of their nearest neighbors has been observed in many plant populations and is most often attributed to variation in microsite quality. We demonstrate another potentially important cause, using a simple spatial simulation model in which a plant's size is determined by its available area plus stochastic variation. If the spatial arrangement of individuals is nonuniform and local crowding reduces individual size, a positive correlation between the size of a plant and the size of neighboring individuals is to be expected. If a plant is small because it is crowded, its nearest neighbors will also tend to be crowded and therefore small. Such positive correlations will be observed whenever any trait of an object is related to the area available to it. Looking at the performance of neighboring objects without explicitly considering distance can give a very misleading signal. [ABSTRACT FROM AUTHOR]

Liverworts are probably the earliest-diverging group of green land plants, but in contrast to mosses and vascular plants, there has been only limited information on the physiology of desiccation tolerance and none on the cytological consequences of de- and rehydration in this group. We explore the physiological and cytological effects of drying and rewetting in several desiccation-tolerant liverworts and examine parallels with and differences from vascular plants and mosses. Observations were made of water-stress responses and recovery using infrared gas analysis and modulated chlorophyll fluorescence, and structural and ultrastructural changes were observed with light and electron microscopy. Dehydration elicits profound cytological changes: fragmentation of the vacuole, rounding of the chioroplasts and mitochondria with thylakoids, and cristae becoming rearranged but remaining undamaged. These changes closely parallel those seen in mosses and desiccation-tolerant vascular plants, as does recovery of the chlorophyll-fluorescence parameter Fv/Fm, which shows half- recovery within minutes or an hour or two but returns to normal, unstressed values only after 24-48 h. As in mosses, de-and rehydration are associated with the de- and repolymerization of the cortical microtubule cytoskeleton. Particularly interesting and described here for the first time is the behavior of the oil bodies, membrane-bound organelles unique to liverworts. In the dry state, these remain substantially unchanged, but after rewetting, they become flattened and regain their normal morphology only after 48 h. When subjected to unnaturally fast rate of drying, the oil bodies, together with other organelles, disintegrate on rewetting. Our findings—that the major changes associated with de- and rehydration in liverworts closely parallel those in mosses and, indeed, vascular plants—imply that the basic physiology and cytology of desiccation tolerance is ancestral in land plants. The unexpected discovery that the oil bodies, while retaining their original volume during drying, collapse during rehydration suggests a shifting of soluble carbohydrates or other moieties into the cytosol and provides the first experimental evidence that the oil bodies may have a crucial role in desiccation tolerance. [ABSTRACT FROM AUTHOR]

Linkages among leaf traits and environment have most often been tested across communities but infrequently within lineages. We studied seven endemic Hawaiian Plantago taxa radiated across elevations, climates, and habitats. We grew plants of six taxa in controlled conditions for 1-2 yr and collected leaves from a seventh in the field. For all taxa, we measured 46 leaf traits and tested hypotheses for trait-environment and trait-trait associations. Because of the rarity of the study plants, our study included low replication within taxa and multiple growth locations; despite these limitations, given reasonable assumptions, our analyses pointed to genetic differentiation among taxa. The leaves of bog taxa were smaller and thicker than those of woodland taxa, with higher leaf mass per area (LMA), stomatal pore area per leaf area, and carbon isotope discrimination (δ13C). Taxa from higher elevations had thicker leaves and higher LMA, as well as lower nitrogen per mass and higher adaxial stomatal distribution. Taxa of drier sites had higher vein density and δ13C. Many traits were allometrically related to leaf area, including stomatal density, major vein densities, and xylem conduit numbers and dimensions. Stomatal and xylem traits were correlated, indicating a matching of hydraulic supply and demand. Leaf diversification in Hawaiian Plantago involved coordinated trait shifts, generating strong, apparently adaptive trait linkages. [ABSTRACT FROM AUTHOR]

Roussea simplex is the sole member of the endemic family Rousseaceae from Mauritius. Once widespread and locally common onMauritius, today R. simplex is critically endangered, with 85-90 known remaining individuals in a few scattered populations. We documented the unusual flowering and fruiting phenology and studied the pollination and seed dispersal ecology of R. simplex in the accessible flowering and fruiting populations. Endemic diurnal Phelsuma cepediana geckos were the only pollinators and the only animals eating the pulp and dispersing the tiny seeds. In experiments with captive geckos, we confirmed that geckos ingest the seeds and pass them apparently unharmed. Thismakes R. simplex one of the fewknownplants that use the sameanimal species for both pollination and seed dispersal. However, none of the seeds from fruits or gut-passed seeds germinated, highlighting the large gap that remains in our understanding of the germination and regeneration of R. simplex. Conservation managementmust address this in the near future to avoid extinction of this unique lineage, and we highlight several options for applied conservation. [ABSTRACT FROM AUTHOR]

Calycanthaceae, sister to all other Laurales, are the most distinct family of the order in their gynoeciumstructure (lateral placentation, presence of two ovules). Gynoeciumstructure was studied in a representative of each genus of Calycanthaceae and gynoecium development in a representative of each of the two subfamilies (Calycanthoideae andIdiospermoideae).Newly foundshared features are postgenital coherence between the free carpels (extragynoecial compitum), abortion of the upper of the two ovules, and lobation of the outer integument.Differences in reproductive structures between the two subfamilies are reviewed. Newly found differences include carpel primordium shape, contribution of the outer integument tomicropyle formation, epidermis differentiation of the rim of the integuments, and mode of formation of the compitum. Unexpectedly, at anthesis, ovary and ovules of Idiospermum are not larger than those ofCalycanthoideae, despite the conspicuous difference in fruit. The identity of ''staminodes'' (sterile organs between stamens and carpels) is discussed. Sterile carpel-like structures (carpellodes) are documented in Idiospermum. The lateral ovule position in Calycanthaceae is correlatedwith a different development of carpel closure as compared with core Laurales, which exhibit median ovule position. Gynoecium morphology of fossil Calycanthaceae and its implications for gynoecium evolution in Calycanthaceae and Laurales are discussed. [ABSTRACT FROM AUTHOR]