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Leaf teeth are projections on the leaf blade margin. They are structurally variable, with characters that are important for taxonomy and phylogeny, but there is a paucity of information on the anatomy of these structures and little understanding of the features and their functions. Here we describe and compare the leaf tooth anatomy of 47 eudicot species. Toothed margin samples from leaves at different developmental stages were collected, fixed and studied under light and scanning electron microscopy. We identified eight leaf tooth morphotypes, six of which occurred with glands. Hydathodes were the most common glands, being found in 11 species; colleters were found in ten species and extrafloral nectaries were found in two species. Cunonioid teeth either devoid of glands or associated with hydathodes were found in Lamiales, Asterales and Apiales. Dillenioid teeth associated with hydathodes were found in Dilleniales. Spinose teeth associated with colleters were found in Aquifoliales. In rosids, we found begonioid, malvoid, theoid, urticoid and violoid teeth, which may be associated with either colleters or nectaries or lack an associated gland. For each family studied, there was only one type of association between gland and tooth, demonstrating the systematic potential of these glands in eudicots. [ABSTRACT FROM AUTHOR]

Aims Plants have limited resources for defenses and species that invest in biotic defenses might exhibit leaves that invest less in other types of defenses. We have investigated whether plants that have few mechanical defenses, but have extrafloral nectaries (EFNs) patrolled by ants, are less prone to herbivory, compared with plants without EFNs that have tougher leaves. Methods Data from the literature were extracted to examine the reported levels of herbivory in plants with or without EFNs. In a savanna vegetation in southern Brazil, field data were collected in leaves from six tropical species and herbivory and specific leaf area (SLA) levels were measured. We further evaluated differences in herbivory and SLA among species and between plants with or without EFNs. In order to test the relationship between herbivory and leaf toughness we regressed average herbivory and average SLA per plant. Important Findings Plants exhibited variable levels of leaf damage, but plants without ant defenses experienced the highest levels of leaf area loss to herbivory. Levels of mechanical defenses were also variable among the plant species. Plants without EFNs were tougher, exhibiting lower values of SLA. Although plants without EFNs had more sclerophyllous leaves, this mechanical defense was not sufficient to impair and/or reduce herbivore feeding, suggesting that the biotic defenses performed by patrolling ants might be more effective than investment in mechanical defenses associated with leaf palatability. [ABSTRACT FROM AUTHOR]

Abstract The family Lauraceae is a major component of tropical and subtropical forests worldwide, and includes some commercially important timber trees and medicinal plants. However, phylogenetic relationships within Lauraceae have long been problematic due to low sequence divergence in commonly used markers, even between morphologically distinct taxa within the family. Here we present phylogenetic analyses of 43 newly generated Lauraceae plastomes together with 77 plastomes obtained from GenBank, representing 24 genera of Lauraceae and 17 related families of angiosperms, plus nine barcodes from 19 additional species in 18 genera of Lauraceae, in order to reconstruct highly supported relationships for the Lauraceae. Our phylogeny supports the relationships: sisterhood of the Lauraceae and a clade containing Hernandiaceae and Monimiaceae, with Atherospermataceae and Gomortegaceae being the next sister groups, followed by Calycanthaceae. Our results highlight a monophyletic Lauraceae, with nine well‐supported clades as follows: Hypodaphnis clade, Beilschmiedia–Cryptocarya clade, Cassytha clade, Neocinnamomum clade, Caryodaphnopsis clade, Chlorocardium–Mezilaurus clade, Machilus–Persea clade, Cinnamomum–Ocotea clade, and Laurus–Neolitsea clade. The topology recovered here is consistent with the patterns of plastome structural evolution and morphological synapomorphies reported previously. More specifically, flower sex, living type, inflorescence type, ovary position, anther locus number, leaf arrangement, leaf venation, lateral vein number, tree height, and inflorescence location all represent morphological synapomorphies of different lineages. Our findings have taxonomic implications and two new tribes, Caryodaphnopsideae and Neocinnamomeae, are described, and the composition of four other tribes is updated. The phylogeny recovered here provides a robust phylogenetic framework through which to address the evolutionary history of the Magnoliids, the third‐largest group of Mesangiospermae. [ABSTRACT FROM AUTHOR]

Staminal glands are an important character in the taxonomy of several Malpighiaceae genera, such as Banisteriopsis, Byrsonima, Diplopterys, Peixotoa and Stigmaphyllon, but only recently few studies started to elucidate the anatomy and ecological functions of these glands. Most genera showing staminal glands are placed in the Stigmaphylloid clade, one of the ten major lineages recovered in recent phylogenies for Malpighiaceae. Here, we identified the nature of the staminal glands from 25 Stigmaphylloid species aiming to characterize their micromorphology, anatomy and exudate histochemistry. Scanning electron and light microscopy were applied to examine the stamens of fresh collected or herborized flowers. All Stigmaphylloid representatives showed elaiophores, osmophores or both glands comprising the epidermal cells in the connective, anther or both regions of the stamen. Elaiophores were distinct into three structural patterns: (1) trichomatous, (2) secretory globose epidermis (3) and overlapping globose epidermal cells. These glands were identified mainly by the occurrence of fatty acids composing the secretion within the cells. Osmophores were always identified as unicellular papillae. Elaiophores and osmophores in the stamen seems to be homoplastic in Malpighiaceae, identified in the Stigmaphylloid clade and in the outgroup representative Byrsonima spicata. Osmophores were restricted to the connectives of Camarea and Cottsia, and at different positions in the anther epidermis of Byrsonima spicata, probably linked to their unique pollination syndromes. This is the first effort in understanding the evolutionary patterns of these glands in Malpighiaceae and should shed light on further studies comprising the remaining lineages of this family. [ABSTRACT FROM AUTHOR]

Thurniaceae are positioned at the base of the cyperids, in Poales, as a sister group of Cyperaceae + Juncaceae. However, Rapateaceae + Mayacaceae have emerged related to these families in a recent phylogenetic study. Although Thurniaceae are morphologically similar to Juncaceae, studies are needed to evaluate characters with systematic value and that may help comprehend the reproductive biology in the family. In this regard, we investigate the floral morphology and anatomy of Prionium serratum and Thurnia sphaerocephala using standard techniques of scanning electron microscopy and light microscopy. The flowers of both species are trimerous, pentacyclic, with diplostemonous androecium and tricarpellate syncarpous gynoecium. Nevertheless, dimerous flowers with an inconsistent number of stamens also occur in T. sphaerocephala. Most floral traits of Thurniaceae are shared with Juncaceae and indicate putative plesiomorphies in the cyperids. However, no consistent data corroborates a link between Rapateaceae and Mayacaceae and the cyperids. The perigonium of Thurniaceae has diagnostic characters for the family, but also for each one of the species studied. The androecium is similar in P. serratum and T. sphaerocephala. In the gynoecium, the number of ovules, the length of the ovary zones, and the occurrence of ovary wall intrusions distinguish P. serratum from T. sphaerocephala and may have a correlation in the cyperids. Furthermore, the type of inflorescence, the color of flowers, and the type of stigma suggest that P. serratum is wind-pollinated and that T. sphaerocephala is insect-pollinated. [ABSTRACT FROM AUTHOR]

In Bromeliaceae, fruit type and seed morphology have been used to distinguish the subfamilies. We studied seed and fruit development of three species of Bromelioideae (Aechmea bromeliifolia , Billbergia distachia and Neoregelia bahiana) relating seed characters to fruit structure. Aechmea bromeliifolia has few ovules per locule inserted within the apical portion of the ovary and the seeds are larger, with a long chalazal appendage, growing towards the fruit base. In B. distachia and N. bahiana , the ovules are numerous and subapically to centrally inserted in the ovary; the seeds are smaller, with a radial disposition, and the chalazal appendages are short (B. distachia) or absent (N. bahiana). The chalazal appendages grow during seed development, and thus their presence/length may be related to the number of ovules/seeds per locule and to the disposition of the ovules inside the locules. The fruits are berries, and juiciness is promoted by mesocarp cells and by substances secreted inside the locules by the placental obturator at later stages of fruit development. These fruit and seed features are strategies for zoochory and provide evidence that each species studied is dispersed by a different type of animal. [ABSTRACT FROM AUTHOR]

Nectar production dynamics can show inter- and intraspecific variation, which can be associated with environmental and ecological factors and with the ultrastructural diversity of the floral nectary. In this context, we recorded nectar production dynamics from a morphofunctional perspective using the hummingbird-pollinated Billbergia distachia (Bromeliaceae). The scale-throated hermit Phaethornis eurynome was the only floral visitor observed, indicating a specialized pollination system. Nectar production showed significant differences between day and night, and the periods of major pollinator activity and nectar secretion were synchronous. The ultrastructural features of the nectary showed some evidence of nectar reabsorption in flowers at night, and it can be inferred that this process may be a key factor in the nocturnal pause in nectar production. In this way, nectary morphoanatomy, nectar traits and an energy-saving mechanism through nectar reabsorption contribute to the well-established relationship between B. distachia and P. eurynome. [ABSTRACT FROM AUTHOR]

Astraea is a genus of tribe Crotoneae (Euphorbiaceae: Crotonoideae) widely distributed in the Neotropical region. Its highest diversity is found in eastern Brazil, and a few weedy species were most likely introduced and naturalized in the Paleotropics. Species of Astraea may be recognized by the usually deeply lobed leaves, lacking basilaminar or acropetiolar nectaries; spiciform inflorescence with bisexual cymules at the base and staminate cymules toward the apex; pistillate flowers with a segmented nectary and multifid styles; staminate flowers with an imbricate calyx, petals bearing dense moniliform trichomes at the basal portion of their margin and 11–15 stamens; and usually tetragonal and verrucose seeds, bearing a caruncle. Based on recent advances in the taxonomic and systematic knowledge of Astraea, we present a taxonomic revision of the genus. Thirteen species are recognized based on morphological characters. We present a full review of morphology and geographical distribution of the genus, along with data on ecology, phytochemistry and medicinal uses, gathered from the literature and fieldwork. Along with an identification key to the species, we provide descriptions, illustrations and photographs, as well as etymology and vernacular names, geographical distribution and ecology, conservation status and comments on taxonomic and nomenclatural matters. Fifteen lectotypes and three neotypes are newly designated here. [ABSTRACT FROM AUTHOR]

Under in vitro culture conditions, plants may present physiological and anatomical disorders, which can interfere negatively after ex vitro transfer. The aim of this investigation was to analyze the impacts of natural ventilation and sucrose supply on the anatomy and physiology of Vriesea imperialis. Plants previously grown in vitro were transferred to culture medium containing 0, 15, 30 or 45 g L−1 sucrose. Three different culture container sealing systems were tested: lids with a green filter (81.35 gas exchanges per day), yellow filter (13.09 gas exchanges per day) or lids with a yellow filter covered with three layers of transparent polyvinylchloride (PVC) film (blocking fluent gas exchange). Sucrose concentrations influenced thickness, lignin and suberin deposition of exodermis cell wall. The modifications verified in leaves, such as higher density of stomata and trichome scales, showed that sucrose can induce osmotic stress in the plants. Photomixotrophic conditions, using containers with intermediate rate of gas exchange (yellow filter) and with 15–30 g L−1 sucrose, produced an improvement in the growth traits and did not induce anatomical and physiological disturbances. [ABSTRACT FROM AUTHOR]

The initial seminal studies of flower developmental genetics were made from observations in several eudicot model species, particularly Arabidopsis and Antirrhinum. However, an increasing amount of research in monocot model and crop species is finally giving the credit that monocots deserve for their position in the evolutionary history of Angiosperms, their astonishing diversification and adaptation, their diversified floral structures, their pivotal function in most ecosystems on Earth and, finally, their importance in agriculture and farming, economy, landscaping and feeding mankind. Rice is a staple crop and the major monocot model to study the reproductive phase and flower evolution. Inspired by this, this chapter reviews a story of highly conserved functions related to the ABC model of flower development. Nevertheless, this model is complicated in rice by cases of gene neofunctionalization, like the recruitment of MADS-box genes for the development of the unique organs known as lemma and palea, subfunctionalization, and rewiring of conserved molecular pathways., (© 2023. Springer Science+Business Media, LLC, part of Springer Nature.)

This is the first study on pollen from Xyris complanata using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Pollen in various conditions, including acetolysed, hydrated, and dehydrated states, were examined. The results show that X. complanata plants disperse their pollen in a linear polyad, comprising a cohesive elongate uniplanar tetragonal tetrad aggregate, consisting of 4 to 10 tetrads per unit. The cohesion within and between tetrads is accomplished by means of the fusion of the tectum. The individual grains are medium in size, pollen grains of intermediary tetrad are quadrangular in both polar and equatorial views, pollen grains of apical tetrad are obovoid in shape, both are triangular in frontal equatorial view, exine 3.0 ± 0.2 μm thick, ulcerate covered with a fossulate–perforate operculum, and heterobrochate microreticulate–perforate sculpturings. Pollen wall consists of the tectum, columellae, footlayer, and endexine, with pollenkitt. The dispersal unit and apertural type are distinctive characters, since, among Xyris, such features can only be found in pollen of X. complanata. The results of the present study contribute useful characters for the systematic study of plants in the genus Xyris. [ABSTRACT FROM AUTHOR]

The chemical composition of the cell walls strongly affects water permeability and storage in root tissues. Since epiphytic orchids live in a habitat with a highly fluctuating water supply, the root cell walls are functionally important. In the present study, we used histochemistry and immunocytochemistry techniques in order to determine the composition of the cell walls of root tissues of 18 epiphytic species belonging to seven subtribes across the Orchidaceae. The impregnation of lignin in the velamen cells reinforces its function as mechanical support and can facilitate apoplastic flow. Pectins, as well cellulose and lignins, are also essential for the stability and mechanical support of velamen cells. The exodermis and endodermis possess a suberinized lamella and often lignified walls that function as selective barriers to apoplastic flow. Various cortical parenchyma secondary wall thickenings, including phi, reticulated, and uniform, prevent the cortex from collapsing during periods of desiccation. The presence of highly methyl-esterified pectins in the cortical parenchyma facilitates the formation of gels, causing wall loosening and increased porosity, which contributes to water storage and solute transport between cells. Finally, cells with lipid or lignin impregnation in the cortical parenchyma could increase the water flow towards the stele. [ABSTRACT FROM AUTHOR]

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There is very scanty information concerning the floral nectary structure and nectar secretion in Prunus laurocerasus L. Therefore, the aim of the study was to determine the micromorphology, anatomy and ultrastructure of nectaries; the abundance of nectar production; and the quantitative and qualitative composition of sugars contained in the nectar of two P. laurocerasus cultivars: 'Schipkaensis' and 'Zabeliana'. The nectary structure was studied using light, fluorescence, scanning and transmission electron microscopy techniques. The nectar sugars were analysed with HPLC. The 'Schipkaensis' had longer inflorescences with a larger number of flowers and a longer perianth than 'Zabeliana'. The micromorphological structure of the nectaries in 'Schipkaensis' exhibited denser (approx. 39%) and larger (approx. 50%) stomata and thicker (approx. 13%) cuticular striae forming wider bands (approx. 26%) than in 'Zabeliana'. The results provide new data on the micromorphology, anatomy and ultrastructure of these floral nectaries. Nectary cuticle ornamentation as well as the size, type and density of stomata and stomatal complex topography can have a diagnostic value in Prunus. The nectar sugar weight indicates a significant apicultural value of the cherry laurel, especially in the case of 'Schipkaensis'. Cherry laurel is an entomophilous species recommended for cultivation in nectariferous zones and insect pollinator refuges; however, climatic conditions eliminating the invasiveness of these plants should be considered. [ABSTRACT FROM AUTHOR]

Extrafloral nectaries (EFNs) mediating ecologically important ant–plant protection mutualisms are especially common and unusually diverse in the Leguminosae. We present the first comprehensively curated list of legume genera with EFNs, detailing and illustrating their systematic and phylogenetic distributions, locations on the plant, morphology and anatomy, on the basis of a unified classification of EFN categories and a time-calibrated phylogeny, incorporating 710 of the 768 genera. This new synthesis, the first since Mckey (1989)'s seminal paper, increases the number of genera with EFNs to 153 (20% of legumes), distributed across subfamilies Cercidoideae (1), Detarioideae (19), Caesalpinioideae (87) and Papilionoideae (46). EFNs occur at nine locations, and are most prevalent on vegetative plant parts, especially leaves (74%) and inflorescence axes (26%). Four main categories (with eight subcategories) are recognised and include the following: formless, trichomatic (exposed, hollow), parenchymatic (embedded, pit, flat, elevated) and abscission zone EFNs (non-differentiated, swollen scars). Phylogenetic reconstruction of EFNs suggests independent evolutionary trajectories of different EFN types, with elevated EFNs restricted almost exclusively to Caesalpinioideae (where they underwent spectacular morphological disparification), flat EFNs in Detarioideae, swollen scar EFNs in Papilionoideae, and Cercidoideae is the only subfamily bearing intrastipular EFNs. We discuss the complex evolutionary history of EFNs and highlight future research directions. [ABSTRACT FROM AUTHOR]

Morpho-anatomical studies of fruits are scarce in monocotyledons and particularly for the Brazilian species of Velloziaceae, a small family of monocots characteristic of the campo rupestre vegetation of Brazil. The main fruit types found in Velloziaceae are poricidal and loculicidal capsules, but capsule morphology is variable, which has led to discrepancies regarding fruit descriptions and terminology. In this study, we aimed to analyse fruit development in Brazilian Velloziaceae to obtain a better understanding of capsule dehiscence and to elucidate and describe in detail the fruit types occurring in the family. Based on our results, we discuss the terminology used to describe capsules of some species, e.g. capsules of Vellozia minima and V. epidendroides , previously classified as poricidal, should be called apical loculicidal, as they form three slits on the uppermost part of each carpel that are prevented from extending downwards by the precocious lignification of the pericarp. Capsules of Barbacenia purpurea , B. riparia and B. plantaginea have been classified using various terms, but they fit the definition of fissuricidal capsule and should be classified as such. We also propose an improved analysis for the character 'fruit type', previously used in phylogenetic reconstructions of Velloziaceae. We changed some states following the fruit reclassification proposed here and added a new state, 'capsule opening through lateral irregular aperture', to the character. Additionally, eight new phylogenetic characters derived from ovary and fruit characteristics are suggested. [ABSTRACT FROM AUTHOR]

Mayacaceae are a small and monogeneric aquatic family including 4–6 species and with an unstable phylogenetic position within Poales. Therefore, the floral development and vasculature were studied in Mayaca fluviatilis and Mayaca sellowiana to better understand interfamilial relationships. In both species, the floral vascular system is organized in six central complexes from which the traces of all floral parts diverge. Both sepals and petals receive three traces, but in the sepals the median and lateral traces do not originate from the same vascular complex, whereas in the petals the median and lateral traces originate from the same complex. Both, ventral and dorsal carpellary traces, vascularize the ovary wall, ascending to the stigma. The sepals are the first organs to be initiated and have a rapid growth. Such structures exhibit glandular trichomes on their margins and remain united, protecting the inner whorls. After sepal development, the petals and the stamens of the outer whorl are initiated, followed by the gynoecium, which appears as an annular primordium. The petals have a markedly delay in development. In M. fluviatilis, the anthers may dehisce before anthesis and self-pollination occurs in the bud. The reduction (loss) of the inner stamen whorl and gynoecium development from an annular primordium link Mayacaceae to the cyperids (Poales). A high similarity in respect to floral vasculature was observed between Mayacaceae and Commelinaceae (Commelinales). [ABSTRACT FROM AUTHOR]

Anarthria, Lyginia and Hopkinsia, endemic to south-western Western Australia, differ from the rest of Restionaceae sensu APG IV in the presence of dithecal rather than monothecal anthers. Dithecal and monothecal Restionaceae form two well-supported sister clades in molecular phylogenetic trees, but shared morphological features of Anarthria, Lyginia and Hopkinsia known so far are either symplesiomorphies (e.g. anther structure) or are characters that are homoplastic in monocots (e.g. absence of silica in culms). The taxonomic placement of the three genera has been controversial during the 20th century, including the idea of recognizing three monogeneric families. As comparative morphological data covering all three genera are limited, we provide a study of female flower structure and development in this group. This is the first developmental study of dithecal Restionaceae that uses scanning electron microscopy. With many more investigated characters, like earlier studies, we found no potential synapomorphies for the dithecal clade. However, we found the first morphological support for the conclusion from molecular data of a sister relationship between Hopkinsia and Lyginia. They share ovules with length not exceeding the width and the micropyle oriented towards the dorsal side of the carpel, which is probably a synapomorphy. Some other characters shared by the two genera could be plesiomorphic, such as inner whorl tepals that are shorter than the gynoecium throughout development. Contrary to some earlier reports, female flowers of all three genera are arranged in spikelets and do not have bracteoles. These characters are thus conserved across the restiid and graminid clades. The gynoecium of Hopkinsia is unicarpellate and not pseudomonomerous. Gynoecia with a single fertile ovule appeared several times and through different morphological pathways in the evolution of wind-pollinated Poales. [ABSTRACT FROM AUTHOR]

Oxygyne Schltr. (Thismiaceae) is a rare and little-known genus of achlorophyllous mycoheterotrophic perennial herbs with one of the most remarkable distributions of all angiosperm plant genera globally, being disjunct between Japan and West–Central Africa. Each species is known only from a single location, and in most cases from a single specimen. This monographic study names, describes and maps two new species, Oxygyne duncanii Cheek from cloud forest in SW Region Cameroon and O. frankei Cheek from gallery forest in the Central African Republic, representing the first new Oxygyne species described from Africa in 112 years, and raising the number of described Oxygyne species from four to six. Oxygyne duncanii is remarkable for sharing more morphological characters with two of the three Japanese species (O. hyodoi C.Abe & Akasawa, O. shinzatoi (H. Ohashi) Tsukaya) than with the geographically much closer type species of the genus, O. triandra from Mt Cameroon. Based mainly on herbarium specimens and field observations made in Cameroon and Japan during a series of botanical surveys, we provide descriptions, synonymy, mapping and extinction risk assessments for each species of Oxygyne, together with keys to the genera of Thismiaceae and the species of Oxygyne. The subterranean structures of African Oxygyne are described for the first time, and found to be consistent with those of the Japanese species. We review and reject an earlier proposal that the Japanese species should be segregated from the African species as a separate genus, Saionia Hatus. The only character that separates the two disjunct species groups is now flower colour: blue or partly-blue in the Japanese species compared with orange-brown in the African species. Studies of the pollination biology and mycorrhizal partners of Oxygyne are still lacking. Two of the six species, O. triandra Schltr. and O. hyodoi, appear to be extinct, and the remaining four are assessed as Critically Endangered using the IUCN 2012 criteria. To avoid further extinction, an urgent requirement is for conservation management of the surviving species in the wild. Since few achlorophyllous mycoheterotrophs have been successfully cultivated from seed to maturity, ex situ conservation will not be viable for these species and protection in the wild is the only viable option. While natural habitat survives, further botanical surveys could yet reveal additional new species between Central Africa and Japan. [ABSTRACT FROM AUTHOR]

Background and Aims Apomixis is an asexual reproductive mode via seeds that generate maternal clonal progenies. Although apomixis in grasses is mainly expressed at the polyploid level, some natural diploid genotypes of Paspalum rufum produce aposporous embryo sacs in relatively high proportions and are even able to complete apomixis under specific conditions. However, despite the potential for apomixis, sexuality prevails in diploids, and apomixis expression is repressed for an as yet undetermind reason. Apomixis is thought to derive from a deregulation of one or a few components of the sexual pathway that could be triggered by polyploidy and/or hybridization. The objectives of this work were to characterize and compare the reproductive development and the timing of apospory initial (AI) emergence between diploid genotypes with potential for apomixis and facultative apomictic tetraploid cytotypes of P. rufum. Methods Reproductive characterization was performed by cytoembryological observations of cleared ovaries and anthers during all reproductive development steps and by quantitative evaluation of the ovule growth parameters. Key Results Cytoembryological observations showed that in diploids, both female and male reproductive development is equally synchronized, but in tetraploids, megasporogenesis and early megagametogenesis are delayed with respect to microsporogenesis and early microgametogenesis. This delay was also seen when ovary growth was taken as a reference parameter. The analysis of the onset of AIs revealed that they emerge during different developmental periods depending on the ploidy level. In diploids, the AIs appeared along with the tetrad (or triad) of female meiocytes, but in tetraploids they appeared earlier, at the time of the megaspore mother cell. In both cytotypes, AIs can be seen even during megagametogenesis. Conclusions Overall observations reveal that female sexual reproductive development is delayed in tetraploids as compared with diploid genotypes, mainly at meiosis. In tetraploids, AIs appear at earlier sexual developmental stages than in diploids, and they accumulate up to the end of megasporogenesis. The longer extension of megasporogenesis in tetraploids could favour AI emergence and also apomixis success. [ABSTRACT FROM AUTHOR]

Inflorescence morphology in Poaceae subtribes Hilariinae, Monanthochloinae, Boutelouinae, Scleropogoninae and Muhlenbergiinae (Cynodonteae, Chloridoideae) has been revisited recently, but inflorescence development remains largely unexplored. The aim of this study is to contribute additional information on the development of inflorescences in Cynodonteae by generating data on Distichlis, Bouteloua, Munroa, Erioneuron and Muhlenbergia and to compare them with results for other grasses. Using scanning electron microscopy images, we identified common developmental patterns among grasses and described developmental novelties for Bouteloua, Distichlis and Muhlenbergia. Novel developmental features are: the amphipetal initiation of second-order branches along the inflorescence of B. curtipendula, the elongation of the internodes of the inflorescence branches before floral development in M. asperifolius and 'Type II' unisexual flowers in D. acerosa. Variable traits among studied species are: inflorescence symmetry, direction of branch and spikelet initiation and differentiation, number of developing stamens, glume developmental patterns and timing of the arrest of gynoecium development during the formation of unisexual flowers. Our results allow us to postulate that a delicate balance of phytohormones may direct early development of grass inflorescence branching system by controlling direction of first-order branch differentiation. The approach used here provides a link between definitive structures and the underlying genetics. [ABSTRACT FROM AUTHOR]

Carpels and ovules have been differently interpreted over the past two centuries. In this review, some of these interpretations are highlighted, with particular emphasis on the current situation. Ovules are part of and are enclosed in carpels in all living angiosperms. Living angiosperms are monophyletic, and the evolutionary association between ovules and the leaf-like part, the carpel wall, had taken place at or before the time the clade of extant angiosperms was established. From what we know at present, there are no 'cauline' ovules in extant angiosperms. Developmentally, carpel walls and ovules are not always synchronous across all extant angiosperms. In early development ovules may be relatively precocious or relatively late compared with carpel walls. They are late in early-diverging angiosperms (ANITA grade, magnoliids, some early-diverging eudicots) but precocious in some more derived groups (e.g. some Caryophyllales and Primulaceae). Carpel primordia have a certain depth in the floral apex, and the entire activated area of a carpel primordium may be several cell layers thick. Thus, the carpel is 'embedded' or 'rooted' within the remaining floral apex. The parts of a carpel develop at different times in carpel ontogeny and probably evolved at different times on the line leading to the angiosperms, which needs to be considered in interpretations. Carpel development depends on a complex genetic network, which increased stepwise over evolutionary time and contains hundreds of genes revealed in molecular developmental biology. The evolutionary history of such networks in carpel walls and ovules is unlikely to be easily disentangled, as most of these genes are not transcription factors. [ABSTRACT FROM AUTHOR]

Croton macrosepalus Sodré & M.J.Silva (sp. nov.), a new species found in the states of Bahia, Goiás, and Tocantins, in Brazil, is described and illustrated. Although it is morphologically similar to Croton spica, the novel species can be differentiated from it by having large glandular stipules, entire or sometimes serrulate leaf margins, petioles with 2-8 cylindrical nectary glands at the apex, ovate pistillate sepals, and a hat-shaped caruncle. The habitat, conservation status, phenology, and morphological relationships of the species are also discussed. Morphological data and molecular analyses using ITS and trnL-trnF support the placement of C. macrosepalus and C. spica in Croton sect. Geiseleria. A geographic distribution map, images, notes about the leaf anatomy of both species, and their phylogenetic relationships are provided. [ABSTRACT FROM AUTHOR]

Leaf tooth can indicate several systematically informative features and is extremely useful for circumscribing fossil leaf taxa. Moreover, it can help discriminate species or even higher taxa accurately. Previous studies extract features that are not strictly defined in botany; therefore, a uniform standard to compare the accuracies of various feature extraction methods cannot be used. For efficient and automatic retrieval of plant leaves from a leaf database, in this study, we propose an image-based description and measurement of leaf teeth by referring to the leaf structure classification system in botany. First, image preprocessing is carried out to obtain a binary map of plant leaves. Then, corner detection based on the curvature scale-space (CSS) algorithm is used to extract the inflection point from the edges; next, the leaf tooth apex is extracted by screening the convex points; then, according to the definition of the leaf structure, the characteristics of the leaf teeth are described and measured in terms of number of orders of teeth, tooth spacing, number of teeth, sinus shape, and tooth shape. In this manner, data extracted from the algorithm can not only be used to classify plants, but also provide scientific and standardized data to understand the history of plant evolution. Finally, to verify the effectiveness of the extraction method, we used simple linear discriminant analysis and multiclass support vector machine to classify leaves. The results show that the proposed method achieves high accuracy that is superior to that of other methods. [ABSTRACT FROM AUTHOR]

The aerial environment appears to structurally modify roots, which frequently show specializations for absorbing water and nutrients. Among those specializations are the velamen, a multiseriate epidermis generally composed of dead mature cells, and greater degrees of lignification in the endodermis, exodermis, and pith. Vanilla phaeantha is a hemiepiphyte used here as a model of study to determine which root characteristics demonstrate the most plasticity in response to aerial and terrestrial environments. It produces roots growing under three conditions: (1) aerial and free, growing from the highest branches towards the ground; (2) aerial roots attached to the phorophyte; and (3) terrestrial. Samples taken 3 cm from the apices were used to prepare histological slides. The tissues and other anatomical structures were measured and histochemically characterized. The most plastic characteristics were the external periclinal thicknesses of the exodermis and the total area occupied by the aerenchyma lacunae. The free roots were the longest, did not evidence root hairs, and had the largest number of the aerenchyma lacunae; they also evidenced greater thicknesses of the exodermis in contact with the epidermis walls that helped maintain their shapes. Terrestrial roots had root hairs around the entire circumference and intense infestations of mycorrhiza, indicating their involvement in nutrient acquisition. The adhering roots evidenced free regions similar to those of aerial roots, as well as adhering regions showed characteristics similar to terrestrial roots (with root hairs and mycorrhiza infestations)., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The function of orbicules has been a matter of speculation for a long time and until now no satisfactory answer has been put forward. We propose two hypotheses that could contribute to the elucidation of their function: (1) that anemophilous and 'buzz pollination' species have microechinate orbicules; and (2) that microechinate orbicules are advantageous for pollen release in both pollination modes. To test the first hypothesis, orbicule morphology of species in which the pollen is released by anther shaking (20 anemophilous and three with buzz-pollination) was analysed. We also conducted a literature review, noting the orbicule surface type and the presence of floral traits suggesting that pollen is released by anther shaking. Ninety-two percent of the species with microechinate orbicules are anemophilous or present 'buzz pollination'. Orbicules without spinules are present in species that lack floral traits linked to anther shaking for pollen release. To test the second hypothesis, a computational simulation that reveals the electric field produced by electrostatically charged orbicules was used. Results showed that the field is increased at the tip of each orbicule spinule. Therefore, an anther loculus surface coated by pointed structures increases the repulsion force of the pollen grains. This is an advantage when pollen is released by shaking the anther. Orbicules are small bodies coating the interior of the anther locule that present the same reactions than the exine of pollen grains. Although many speculations were made trying to understand the orbicules role, none of them could be confirmed. We found that anemophilous and 'buzz pollination' species have microechinate orbicules and that the anther loculus surface coated by pointed structures increases the repulsion force of the pollen grains. This is an advantage when pollen is released by shaking the anther. [ABSTRACT FROM AUTHOR]

We present a taxonomic revision of Cremastosperma, a genus of Neotropical Annonaceae occurring in lowland to premontane wet forest, mostly in areas surrounding the Andean mountain chain. We recognise 34 species, describing five as new here: from east of the Andes, C. brachypodum Pirie & Chatrou, sp. nov. and C. dolichopodum Pirie & Maas, sp. nov., endemic to Peru; C. confusum Pirie, sp. nov., from southern Peru and adjacent Bolivia and Brazil; and C. alticola Pirie & Chatrou, sp. nov., at higher elevations in northern Peru and Ecuador; and from west of the Andes, C. osicola Pirie & Chatrou, sp. nov. endemic to Costa Rica, the most northerly distributed species of the genus. We provide an identification key, document diagnostic characters and distributions and provide illustrations and extensive lists of specimens, also presenting the latter in the form of mapping data with embedded links to images available online. Of the 34 species, 22 are regional endemics. On the basis of the extent of occurrence and area of occupancy of species estimated from the distribution data, we designate IUCN threat categries for all species. Fourteen species proved to be endangered (EN) and a further one critically endangered (CR), reflecting their rarity and narrow known distributions. [ABSTRACT FROM AUTHOR]

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The present study provides information on the development of the female and male gametophytes and seed ontogeny characteristics for Trichloris, and it discusses their taxonomic significance to the family Poaceae. Trichloris species are characterized by having 2-3 stamens per floret, tetrasporangiate anthers, a monocotyledonous development of the anther wall, a single middle layer of common origin with the tapetum, fibrous thickening in the cell walls of the endothecium, and a secretory tapetum. These characteristics are constant within Poaceae. The possession of bitegmic and tenuinucellate ovules, laterally positioned antipodals prior to their degeneration, a free exocarp, and an epiblast in the mature embryos gives Trichloris the typical characteristics described for other members of the subfamily Chloridoideae. The degradation of tapetal cells before the maturation of the pollen grain and the absence of aborted ovules indicate a high fertility rate, which is an important feature for perennial halophytes such Trichloris that do not possess elaborate seed dormancy systems. [ABSTRACT FROM AUTHOR]

To better understand the complex pollination biology of Carludovicoideae (Cyclanthaceae), four species from French Guiana were investigated in both the field and laboratory. The pistillate flowers of all species of the subfamily have long staminodes up to 10 cm long or more, which emit scent and apparently attract beetles during anthesis. Scent was collected by standard headspace methods and analyzed in the laboratory by GC/MS. The histology of staminodes, measurements of inflorescence temperatures, and analyses of the floral nutrients were performed. The staminodes have two ducts with a mucilage-like liquid containing sugar, which provides nourishment for beetle visitors. In Evodianthus funifer, four of the six beetle morphospecies (Curculionidae: Acalyptini) were pollinators and oviposited in staminate flowers. The remaining pair of morphospecies were non-pollinators, and avoided entering the inflorescence, while only cutting the staminodes for possible oviposition on the ground. Staminate flowers and staminodes have a high energy content, providing for larval development of the beetles. Our findings revealed that the staminodes released aromatic components, miscellaneous cyclic components, and terpenoids. Some of the major scent compounds of E. funifer and Ludovia lancifolia, i.e., (E,E)-α-farnesene-2(3),9(10)-diepoxid and 3-methylen-2-(pent-2(Z)-enyl)-cyclopentanol, are new to science. Also, Carludovicoideae are a subfamily of plants that attract beetle pollinators through highly specific scent compounds, making them comparable to species of Araceae, Magnoliaceae, and Annonaceae. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Experimental Biology (Botany) is the property of Egyptian Society of Experimental Biology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The flowers of most Anacardiaceae have a floral nectary disk producing nectar rich in sugars. However, a recent study demonstrated that their nectaries might also produce other substances, including lipids and phenolic compounds. To explore the diversity of floral nectary production and (ultra)structure, and their potential for the systematics of Anacardiaceae, we studied seven genera and 13 species from the two subfamilies. We used spectrophotometry to identify sugars and histochemical tests for other substances, and electron and brightfield microscopy to study nectary (ultra)structure and secretory pathways. The composition of sugars and other substances can vary between closely related species and be more similar in species from different subfamilies, being of limited value for the systematics of the family. The general morphology and structure of the floral nectary and their secretory pathways appear to be conservative in the family, and, like the production of mixed secretions, they might be plesiomorphic. Three morphological types of floral nectaries are defined for the family: nectariferous disk with papillose (1) or smooth epidermis-type (2) and trichomatous-type (3). The secretions may be released both by granulocrine and eccrine mechanisms and exuded through nectarostomata or the cuticle. Further studies are needed to better understand their evolutionary and ecological implications in Anacardiaceae and other sapindalean lineages. [ABSTRACT FROM AUTHOR]

Extrafloral nectaries (EFNs) are particularly common in Fabaceae and their morphological diversity has proved taxonomically useful. However, their anatomy remains poorly investigated. In this study we analysed EFN anatomy in 12 species from ten genera of Fabaceae, using scanning electron microscopy and light microscopy. We found three main structural organizations of EFNs. (1) The 'embedded' EFNs (cryptic and externally non-visible) in Bauhinia forficata are secretory prickles in which nectar-secreting tissue is completely embedded within the prickle, representing a new kind of EFNs in plants. Among externally visible EFNs, (2) 'elevated' EFNs were found in seven species, including a Mimosa sp. belonging to a clade considered to lack EFNs, and (3) 'swollen-scar' EFNs derived from the abscission site of aborted buds were found in four species, including a new report in Galactia. In three species, we also found colleters anatomically similar to other colleters reported for Fabaceae. We discuss terminological issues in the (scarce) literature on EFN anatomy in Fabaceae, mainly due to incorrect interpretation of structures or misuse of existing terms. [ABSTRACT FROM AUTHOR]

Oxygyne Schltr. (Thismiaceae) is a rare and little-known genus of achlorophyllous mycoheterotrophic perennial herbs with one of the most remarkable distributions of all angiosperm plant genera globally, being disjunct between Japan and West–Central Africa. Each species is known only from a single location, and in most cases from a single specimen. This monographic study names, describes and maps two new species, Oxygyne duncanii Cheek from cloud forest in SW Region Cameroon and O. frankei Cheek from gallery forest in the Central African Republic, representing the first new Oxygyne species described from Africa in 112 years, and raising the number of described Oxygyne species from four to six. Oxygyne duncanii is remarkable for sharing more morphological characters with two of the three Japanese species (O. hyodoi C.Abe & Akasawa, O. shinzatoi (H. Ohashi) Tsukaya) than with the geographically much closer type species of the genus, O. triandra from Mt Cameroon. Based mainly on herbarium specimens and field observations made in Cameroon and Japan during a series of botanical surveys, we provide descriptions, synonymy, mapping and extinction risk assessments for each species of Oxygyne, together with keys to the genera of Thismiaceae and the species of Oxygyne. The subterranean structures of African Oxygyne are described for the first time, and found to be consistent with those of the Japanese species. We review and reject an earlier proposal that the Japanese species should be segregated from the African species as a separate genus, Saionia Hatus. The only character that separates the two disjunct species groups is now flower colour: blue or partly-blue in the Japanese species compared with orange-brown in the African species. Studies of the pollination biology and mycorrhizal partners of Oxygyne are still lacking. Two of the six species, O. triandra Schltr. and O. hyodoi, appear to be extinct, and the remaining four are assessed as Critically Endangered using the IUCN 2012 criteria. To avoid further extinction, an urgent requirement is for conservation management of the surviving species in the wild. Since few achlorophyllous mycoheterotrophs have been successfully cultivated from seed to maturity, ex situ conservation will not be viable for these species and protection in the wild is the only viable option. While natural habitat survives, further botanical surveys could yet reveal additional new species between Central Africa and Japan. [ABSTRACT FROM AUTHOR]

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Copyright of Rodriguésia is the property of Revista Rodriguesia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Herein, we describe nests of the orchid bee Euglossa cordata that were constructed in cavities of Aechmea distichantha (Bromeliaceae) stolons. We present data about nest and cell size, number of adults and brood, and analyses of larval provisions. The presence of E. cordata carcasses embedded in the resin of nest partitions indicates that these nests were used by multiple generations. Based on larval provisioning, E. cordata is polylectic and relies heavily on a few plant species. [ABSTRACT FROM AUTHOR]

Poaceae have been historically recognized by having homogeneous pollen grains. Most of the available studies have focused on species from open areas, and studies of tropical forest representatives of the family are scarce. Some studies have suggested pollination assisted by insects, contrasting with the traditional anemophily known for this family. We analysed pollen surface of 121 specimens belonging to 87 species, eight tribes and four subfamilies of Poaceae from Neotropical forests, based on scanning electron microscopy method. None of the analysed samples had ectexine without ornamentation. Four different patterns were observed, three mixed and one of them simple: microechinate-areolate (all tribes except Streptochaeteae; 71 species); microechinate-perfurate (12 species); microechinate-rugulate (exclusive to Olyreae, the tribe that includes the herbaceous bamboos and is confined to the understory in the Neotropical region; two species) and microechinate (Bambuseae and Streptochaeteae, two species). The present data broaden the knowledge on the palynology of Poaceae from tropical forests, because 14 genera and 75 species have the pollen surface characterized for the first time in this article. Patterns of ectexine variation, especially in subfamilies Anomochlooideae and Bambusoideae, include differences between and within genera, with application to taxonomic and evolutionary studies, and probably to other fields such as ecology, palaeobotany and reproductive biology in the family. [ABSTRACT FROM AUTHOR]

Not all plant traits from all regions have been standardized or databased. Some ecosystems, such as tropical grasslands, are under-represented in such databases owing to the difficulty in assessing bud banks and evaluating clonal growth. This study aimed to (i) determine whether Brazilian morphological traits of belowground organs can be translated into categories used in the CLO-PLA database and (ii) assess the applicability of clonal and bud bank traits standardized in the CLO-PLA database for Brazilian Aldama species, which have specialized belowground organs and are able to resprout. In all, 165 species, including herbs, subshrubs and shrubs, of 37 genera from different Brazilian ecosystems, were evaluated. Not all the traditional Brazilian morphological categories could be translated into CLO-PLA traits, resulting in a lower number of categories and loss of information regarding plant morphology. Furthermore, clonal and bud bank traits could be only partially evaluated for Aldama, since some traits showed seasonal variation. The CLO-PLA classification focused on the organs in relation to the soil surface, the connection between mother and daughter shoots, and the origin of buds from which daughter shoots sprout. In the Brazilian classification, by contrast, anatomical features or early ontogeny of the organ are very important. Nevertheless, our results might form the basis for future comparative studies across ecosystems and biomes, for which common trait standardization is necessary. However, further research is needed to assess the functional morphology of clonal and bud bank traits in tropical regions. [ABSTRACT FROM AUTHOR]

Premise of research. The flower of Leandra melastomoides (Melastomataceae) exhibits a singular condition that is the presence of two distinct and opposite portions in the sepals forming what is known as a double calyx. These portions may correspond to individual sepals, explaining the recognition of two calyx whorls. No studies resolving this structure are available in the literature. Thus, we aimed to elucidate the nature of the double calyx of L. melastomoides by analyzing its ontogeny. This approach allowed us to test hypotheses about how this structure developed. Methodology. Flowers and buds were preserved and prepared for observation in LM and SEM. Pivotal results. The sepals originate in the margin of the floral apex as six spherical primordia in a single outer whorl. The growth is unidirectional until a basal protuberance arises on the ventral surface of each primordium, which allows us to distinguish an upper and a lower part of this structure. The upper portion later takes on a dorsal position. The lower portion shows laminar growth, various vascular traces, and nonglandular emergences. The dorsal portion becomes conical, is lined with nonglandular emergences, and is supplied by a single vascular trace. The vascularization of each part of a sepal has a common origin from the radial divergence of the same trace that emerges from the vascular ring of the hypanthium. Conclusions. The calyx of L. melastomoides actually consists of only one whorl, because both dorsal and laminar parts of a sepal originate from a single primordiumin a peripheral region of the floral meristem. The dorsal projection is similar to that described in the literature under the term Vorläuferspitze. The understanding of the existence of two distinct ontogenetic modules for the same organ allows us to compare it with other organs and taxonomic groups and to search for a better descriptive terminology for the structure in this group. [ABSTRACT FROM AUTHOR]

The abrupt origin and rapid diversification of the flowering plants presents what Darwin called 'an abominable mystery'. Floral diversification was a key factor in the rise of the flowering plants, but the molecular underpinnings of floral diversity remain mysterious. To understand the molecular biology underlying floral morphological evolution, genetic model systems are essential for rigorously testing gene function and gene interactions. Most model plants are eudicots, while in the monocots genetic models are almost entirely restricted to the grass family. Likely because grass flowers are diminutive and specialized for wind pollination, grasses have not been a major focus in floral evo-devo research. However, while grass flowers do not exhibit any of the raucous morphological diversification characteristic of the orchids, there is abundant floral variation in the family. Here, we discuss grass flower diversity, and review what is known about the developmental genetics of this diversity. In particular, we focus on three aspects of grass flower evolution: (1) the evolution of a novel organ identity-the lodicule; (2) lemma awns and their diversity; and (3) the convergent evolution of sexual differentiation. The combination of morphological diversity in the grass family at large and genetic models spread across the family provides a powerful framework for attaining deep understanding of the molecular genetics of floral evolution. [ABSTRACT FROM AUTHOR]

We provide a detailed comparative study of floral ontogeny and vasculature in Xyridaceae, including Xyris, Abolboda and Orectanthe. We evaluate these data in the context of a recent well-resolved phylogenetic analysis of Poales to compare floral structures within the xyrid clade (Xyridaceae and Eriocaulaceae). Xyrids are relatively diverse in both flower structure and anatomy; many species incorporate diverse and unusual floral structures such as staminodes and stylar appendages. Xyridaceae possess three generally epipetalous stamens in a single whorl; the 'missing' stamen whorl is either entirely absent or transformed into staminodes. Fertile stamens each receive a single vascular bundle diverged from the median petal bundle. In Xyris, the stamen bundle diverges at the flower base, but it diverges at upper flower levels in both Abolboda and Orectanthe. In species of Abolboda that possess staminodes, staminode vasculature is closely associated with the lateral vasculature of each petal. Despite the likely sister-group relationship between Eriocaulaceae and Xyridaceae, our character optimization indicates that the stylar appendages that characterize some Xyridaceae (except Xyris and Achlyphila) are non-homologous with those of some Eriocaulaceae. On the other hand, it remains equivocal whether the loss of a fertile outer androecial whorl occurred more than once during the evolutionary history of the xyrid clade; this transition occurred either once followed by a reversal to fertile stamens in Eriocauloideae and staminodes in some Xyridaceae, or twice independently within both Xyridaceae and Eriocaulaceae. [ABSTRACT FROM AUTHOR]

Background The velamen radicum, a spongy and usually multiple-layered root epidermis composed of dead cells at maturity, is a textbook example of an adaptation that is typically associated with epiphytic orchids. Scope Based on an extensive literature review, the occurrence of this structure was documented in approximately 240 genera of terrestrial monocotyledons (162 orchid and 74 non-orchid genera) and in one genus of dicotyledons. Mapping this character on a phylogenetic tree reveals that a velamen is found throughout the monocotyledons, ranging from members of early-branching Araceae to derived Cyperaceae. Conclusion The current depiction of the velamen radicum in angiosperms and its almost exclusive association with the epiphytic lifestyle in orchids is misleading, which inevitably leads to a biased view of its evolution and function. The findings propose a re-evaluation of the occurrence, evolution and function of the velamen radicum in both terrestrial and epiphytic angiosperms. [ABSTRACT FROM AUTHOR]

While it is reasonable to predict that photosynthetic rates are inhibited while leaves are wet, leaf gas exchange measurements during wet conditions are challenging to obtain due to equipment limitations and the complexity of canopy-atmosphere interactions in forested environments. Thus, the objective of this study was to evaluate responses of seven tropical and three semiarid savanna plant species to simulated leaf wetness and test the hypotheses that (i) leaf wetness reduces photosynthetic rates (Anet), (ii) leaf traits explain different responses among species and (iii) leaves from wet environments are better adapted for wet leaf conditions than those from drier environments. The two sites were a tropical rainforest in northern Costa Rica with ~4200 mm annual rainfall and a savanna in central Texas with ~1100 mm. Gas exchange measurements were collected under dry and wet conditions on five sun-exposed leaf replicates from each species. Additional measurements included leaf wetness duration and stomatal density. We found that Anet responses varied greatly among species, but all plants maintained a baseline of activity under wet leaf conditions, suggesting that abaxial leaf Anet was a significant percentage of total leaf Anet for amphistomatous species. Among tropical species, Anet responses immediately after wetting ranged from -31% (Senna alata (L.) Roxb.) to +21% (Zamia skinneri Warsz. Ex. A. Dietr.), while all savanna species declined (up to -48%). After 10 min of drying, most species recovered Anet towards the observed status prior to wetting or surpassed it, with the exception of Quercus stellata Wangenh., a savanna species, which remained 13% below Anet dry. The combination of leaf wetness duration and leaf traits, such as stomatal density, trichomes or wax, most likely influenced Anet responses positively or negatively. There was also overlap between leaf traits and Anet responses of savanna and tropical plants. It is possible that these species converge on a relatively conservative response to wetness, each for divergent purposes (cooling, avoiding stomatal occlusion, or by several unique means of rapid drying). A better understanding of leaf wetness inhibiting photosynthesis is vital for accurate modeling of growth in forested environments; however, species adapted for wet environments may possess compensatory traits that mitigate these effects. [ABSTRACT FROM AUTHOR]

The root anatomy of bromeliad Nidularium minutum Mez was studied and the efficiency of root system in contributing to the growth, development and mineral uptake of the species evaluated. To accomplish this analysis, four treatments were applied as follows: (i) control plants with 5 mL H2O on substrate and 5 mL H2O into tank;; (ii) plants supplied with nutrients to the tank with 5 mL H2O on substrate and 5 mL Hoagland and Arnon solution into tank;; (iii) plants supplied with nutrients to the roots with 5 mL HA on substrate and 5 mL H2O into tank;; and (iv) plants supplied with nutrients to the tank and roots with 5 mL HA on substrate and 5 mL HA into tank. Biometric variables and biomass were measured. Contents of macro- and micronutrients were evaluated in leaves, and the anatomical structure of roots was analysed. Structurally, the roots possess multiseriate epidermis, termed velamen, which is typical in Orchidaceae and other families for taking up water and nutrients. Plants supplied with nutrients to the roots had higher values than control plants for fresh and dry mass of stems, leaves and total (leaves + stems + roots), besides being more efficient than plants supplied with nutrients to the tank for nitrogen uptake. These results indicate that root system of N. minutum is very efficient for nutrients uptake when compared with the tank contributing to plant growth and development, most likely assisted by the presence of velamen. [ABSTRACT FROM AUTHOR]

The Euphorbiaceae are notable for floral diversity and evolutionary complexity. Croton is the second largest genus in the family and exhibits particular diversity in its flowers. The aim of this study was to investigate the floral ontogeny and structure of three Croton species with distinct morphologies, with a focus on testing the hypothesis that the filaments of female flowers, which have received different interpretations in the literature and are currently described as reduced petals, are staminodes and part of a vestigial androecium. With the ontogenetic study we can understand the origin of the organs and associate these with flower evolution in the genus. Flowers in several stages of development were analysed using light microscopy and scanning electron microscopy. In the early stage of development, the sepals are the first structures to be formed, although they do not continue to grow in female Croton fuscescens Spreng. flowers. Petals are absent in female flowers, with filamentous, petaloid structures, interpreted here as staminodes, alternating with the sepals in Croton lundianus (Didr.) Müll. Arg. In Croton sphaerogynus Baill., the staminodes are located between the nectary lobes. The stamens exhibit centripetal development in the flower bud stage, and the carpels are post-genitally connate, with differences in style branching. Besides the ontogenetic interpretation for the filamentous structures, the genus shows transitional structures that we consider evolutionary reductions. Our results can explain how developmental alterations have influenced the suppression and modification of floral organs in the genus. [ABSTRACT FROM AUTHOR]