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Trema, a genus of the popularly known Cannabaceae, has recently been the subject of cannabinoid bioprospection. T. micrantha is a tree with pharmacological potential widely used in folk medicine. It has two types of glandular trichomes, bulbous and filiform, spread throughout the plant body. Considering the proximity of this species to Cannabis sativa and Trema orientalis, species containing cannabinoids, the glandular trichomes of T. micrantha are also expected to be related to the secretion of these compounds. Thus, this study aims to detail the morphology of secretory trichomes during the synthesis, storing and release of metabolites in T. micrantha. We tested the proposition that they could be a putative type of cannabinoid-secreting gland. Pistillate and staminate flowers and leaves were collected and processed for ontogenic, histochemical, and ultrastructural analyses. Both types of glandular trichomes originate from a protodermal cell. They are putative cannabinoid-secreting sites because: (1) terpene-phenols and, more specifically, cannabinoids were detected in situ; (2) their secretory subcellular apparatus is consistent with that found in C. sativa: modified plastids, polyribosomes, an extensive rough endoplasmic reticulum, and a moniliform smooth endoplasmic reticulum. Plastids and smooth endoplasmic reticulum are involved in the synthesis of terpenes, while the rough endoplasmic reticulum acts in the phenolic synthesis. These substances cross the plasma membrane by exocytosis and are released outside the trichome through cuticle pores. The study of the cell biology of the putative cannabinoid glands can promote the advancement of prospecting for natural products in plants. [ABSTRACT FROM AUTHOR]

Camoensia scandens is a papilionoid legume inserted in the core genistoid clade. It has large, crepuscular, scented flowers but the corolla is non-papilionaceous, which deviates from the pattern found in the subfamily. The vexillum has a folded claw, forming a tube, which is opposed to the androecium opening; all petals have yellow-gold crinkled margins. In addition, there is a long hypanthium, which stores a translucid liquid. The goal of this study is to elucidate the ontogenetic pathways that result in such a peculiar flower and the glands responsible for the sweet fragrance of the petals. Floral buds and flowers were processed for SEM, TEM and light microscopy analyses. Five sepals arise unidirectionally followed by five petals that initiate simultaneously. After the petals, 11 stamens emerge unidirectionally; a pair of adaxial stamens is opposite to the vexillum. In the intermediate developmental stages the sepals unite basally; the two adaxial sepals unite with each other to a greater extent than with the other sepals. The filaments are basally connate, forming a tube with an adaxial opening at the base. The carpel emerges concomitantly with the two abaxial antepetalous stamens. The long hypanthium forms from the outer floral organs (base of the sepals, petals, filaments) and is attached to the base of the stipe. The corolla is noticeable in the intermediate stages of development. The crinkled golden margins house scent glands formed of a secretory epidermis with secretory trichomes and secretory subepidermal cells. The odor is composed of neutral polysaccharides, nitrogenous substances and essential oils. An extensive nectariferous region is found on the inner surface of the hypanthial tube. The nectar is translucent, viscous and released through large pores. The comparison of our data with that of other genistoid flowers enabled discussions about the pollination and systematics of the group. [ABSTRACT FROM AUTHOR]

Parietaria debilis G. Forst. is gynomonoecious, which is a rare condition in the Urticaceae family and among angiosperms. Apetalous flowers of two different morph types (monoclinous, pistillate) occur in the same inflorescence and are reduced in size and in the number of whorls and of organs per whorl. The objective of this study was to compare the morphogenesis of monoclinous and pistillate flowers to determine whether the monoclinous flowers produce fertile gametophytes, and elucidate the pathways leading to the absence of stamens and to the changes in number of whorls and organs per whorl. Flower buds and flowers (non-fertilized, fertilized) were processed for surface and anatomical studies. Pollen ultrastructure and viability were determined. Inflorescences with fertilized flowers were checked for the presence and location of fruits/viable seeds. The monoclinous flower has four sepals, four stamens, and a uniovulate pseudomonomerous gynoecium. In the pistillate flower, the stamens are absent or, rarely, aborted. No petals are formed. The gynoecium is pseudomonomerous, originated as a central primordium that differentiates into two carpels, but only one develops and houses an ovule. Monoclinous and pistillate flowers produce viable seeds. Thus, our data confirmed that this species is indeed gynomonoecious. [ABSTRACT FROM AUTHOR]

The present chapter deals with the concept as well as the structure, ultrastructure and development of laticifer in plants. The morphological aspects of the laticifer development are used to better support the laticifer current classification. Some general functions attributed to the laticifer are discussed, especially those related to the plant protection. As a novelty we cited a role of laticifer presence and distribution in the pollination of the fig trees. An extensive bibliographic survey on taxonomic distribution of laticifers in plants is presented. Illustrations of anatomy, histochemistry and ultrastructure of laticifers are presented to exemplify the treated aspects. Unpublished or recently published aspects are highlighted in each topic. We showed that there is a great diversity of morphological types of laticifers and developmental processes involving the laticifer formation in plants. [ABSTRACT FROM AUTHOR]

The presence of articulated laticifers in the Moraceae family was recently discovered, which means that the location of pectinase and cellulase activities must be of great importance for their growth. Thus, the present study aimed to determine the role of these enzymes in the laticifer growth in Ficus montana and Maclura tinctoria. Reproductive meristems were collected and fixed in Karnovsky. Pectinase and cellulase labeling was performed in part of the samples, while another part was processed for usual TEM analyses. Pectinase and cellulase activities were detected in the vacuole and close to the middle lamella in both species. The presence of cellulases in the laticifers supports their articulated origin. Therefore, the occurrence of pectinase and cellulase activity in the laticifers points out that these enzymes could act in the dissolution of the transverse walls and in the processes of intrusive growth (through the dissolution of the middle lamella) and cell elongation (through the partial disassembly of components of the wall making it more plastic). Both enzymes are synthesized in the endoplasmic reticulum and transported to the cell wall by exocytosis or stored in the vacuole. The species studied showed a diverse subcellular composition, which is probably related to the species and not to the laticifer type (they present the same type) and to the composition of the latex (they show similar latex composition). We conclude that the presence of pectinases and cellulases can be used as a diagnostic condition for the laticifer types (articulated vs. non-articulated). [ABSTRACT FROM AUTHOR]

The stigma plays several roles such as pollen hydration and selection, and pollen tube nutrition. In the Ficus -fig wasp mutualism, stigmata have an additional, almost unknown, function by representing a physical interface for both plant and wasp reproduction. We used light and electron microscopy to compare the detailed morphology of the stigmata of nine Ficus species of different sections and with different pollination modes and sexual expressions. Figs were collected at the stage when the stigmata were receptive for pollination. Stigmata in actively pollinated monoecious species have well developed papillae concentrated on the adaxial surface exposed towards the fig cavity. Conversely, the passively pollinated monoecious species have the whole surface of the stigmata covered by somewhat smaller papillae. In both actively and passively pollinated monoecious species these features are consistent, irrespective of style length. In all actively pollinated gynodioecious species, the stigmata of pistillate flowers were tubular or infundibuliform whereas in almost all actively pollinated monoecious species (except F. racemosa ) the stigmata were filiform, with one branch or two asymmetric branches. In gynodioecious species the short-styled flowers in “male” figs show a limited receptive surface with small papillae, while the stigmata of long-styled flowers in “female” figs are covered by papillae that extend down the sides of the style, increasing the stigmatic surface. In actively pollinated species, stigmata are cohesive, forming a common surface for pollen tube germination (= synstigma). The synstigma arrangement was quite variable: lax, cohesive or very cohesive, with entanglement by stigmatic papillae and stylar trichomes. Entanglement by stylar trichomes is common in gynodioecious species. The synstigma arrangement did not correlate with phylogeny or breeding system. This study is the first to report a very loose synstigma in actively pollinated monoecious Ficus species. Our analyses revealed that, in Ficus , the synstigma is functionally analogous to an extra-gynoecial compitum. Comparative studies will be required to test further hypotheses about the evolutionary determinants of such variation. [ABSTRACT FROM AUTHOR]

Premise of research. This study compares the development of staminate and hermaphrodite flowers of Parkia multijuga and Stryphnodendron adstringens, two andromonoecious mimosoid trees, in order to determine whether diclinous flowers result from the same developmental processes. The issues involving the interesting structure of the perianth were also addressed. Methodology. Flowers and flower buds of various sizes were processed for surface and histological observations. Pivotal results. Five sepal primordia emerge in the floral meristem from the abaxial side in a sequential order in P. multijuga and from the adaxial side of the flower in a modified helical order in S. adstringens. Five petal primordia initiated simultaneously in P. multijuga and S. adstringens. The carpel primordium initiates concomitantly with five antesepalous stamen primordia in P. multijuga and after petal elongation in S. adstringens. All connections among floral organs in P. multijuga (gamosepaly, gamopetaly, epipetaly, and staminal tube) and S. adstringens (gamosepaly and gamopetaly) are postgenital. A sixth sepal primordium found in some S. adstringens flowers is formed late in the development. Early ontogenetic stages are similar between hermaphrodite and staminate flowers of both species, and only in middevelopmental stages does the carpel primordium stop elongating; no ovule, style, or stigma is formed, leaving only a small carpellodium in the center of the staminate flowers. Conclusions. Our ontogenetic studies show that carpel abortion, not carpel absence from inception, results in staminate flowers in two andromonoecious legumes. [ABSTRACT FROM AUTHOR]

Premise of research. Anther glands display great morphological diversity and features with potential ecological and taxonomic value in the Mimosoideae group. The current knowledge about these glands is mainly based on external morphological observations, lacking data on the anatomy of the glands. A detailed anatomical study of the glands is a crucial step toward a more comprehensive understanding about these structures because it provides valuable information for further studies about their ontogeny, functions, and homology. Therefore, the goal of this study was to revisit anther gland anatomy in Mimosoideae species to provide a more detailed characterization. Methodology. We investigated anther glands from 25 species of Mimosoideae placed in different clades. Buds immediately preceding anthesis were collected and fixed in neutral buffered formalin solution. Anthers were removed and processed for surface and anatomical analyses. Pivotal results. We found four main types of anther glands in Mimosoideae. The general Piptadenia type is characterized by a stalked gland with rounded apex and includes three subtypes: Piptadenia, characterized by a gland composed of isodiametric cells; Adenanthera, a gland composed of one epidermal layer and isodiametric central cells; and Entada, composed of one epidermal layer that delimits a lumen. The Pentaclethra type is a robust gland composed of a palisade epidermal layer and isodiametric central cells, with vascularized stalk; the Prosopis africana type is a robust sessile and vascularized gland; and, finally, the Gagnebina type is an acuminate gland with elongated cells. Conclusions. The diversity of anther gland morphology lies in both external and anatomical features. Piptadenia subtype Piptadenia occurs in most of the studied species and likely is the common type for Mimosoideae. Glands with anatomical similarity occur in closely related groups, suggesting that the type of anther gland is a character with potential phylogenetic significance. [ABSTRACT FROM AUTHOR]

Abstract: Calliandra brevipes Benth. is an American shrubby species largely used for ornamental purposes. Like all other Calliandra species it has heteromorphic pollen grains shed in ellipse-shaped, calymmate polyads and a unique mode of pollen presentation by producing a sticky substance called “pollen adhesive”. The present study aimed to investigate in detail the origin of polyad adhesive in C. brevipes. Serial microtome sections of anthers in various developmental stages were used and histochemical tests applied to detect the adhesive production sites and investigate the subcellular characteristics of the anther cells under transmission electron microscopy. The pollen adhesive in C. brevipes is not only produced by parenchymatic cells of the anther transversal septum, as it is described for Calliandra angustifolia, but parenchymatic cells and tapetal cells next to the polyad apical pollen grain also participate in the pollen adhesive production. The cytoplasm of the degenerating tapetum cells contains oleoplasts and fibrogranular material inside the vacuoles which mixes with the adhesive produced by adjacent parenchymatic cells and which therefore contributes to its composition. Vacuoles containing fibrogranular material are very similar to those found in tryphine producing tapetal cells, and the subcellular structures of parenchymatic and tapetal cells are similar to each other. The fact that the pollen adhesive becomes solid in contact with the environment is attributed to dehydration and the presence of the protein fibrogranular material and lipid substances since resin could not be found in its composition. It seems that the sites of pollen adhesive production in Calliandra may vary among its members. Studies of polyad adhesive production in the genus should be standardized in order to verify the information already available in the literature. [Copyright &y& Elsevier]

The genus Miconia, Melastomataceae, has been highlighted for its high proportion of apomictic species, in which the occurrence of low pollen grain viability is commonly recorded. In this study, we compared aspects of pollen development and viability and ploidy level in a sexual species, Miconia pepericarpa, and an apomictic species, Miconia fallax, and investigated the possible causes of pollen grain sterility in apomictic species. Abnormal meiosis was observed only in apomictic M. fallax and leads to the formation of inviable pollen grains, often with little or no cytoplasmic content. Furthermore, the apomictic species is polyploid, and therefore, chromosomal imbalance would be expected. Symmetric mitotic division was found only inM. fallax, also resulting in inviable pollen grains, usually with cytoplasm content but without generative cell differentiation. At the end of development, the apomictic species also displays another difference when compared with the sexual species: the generative cell does not become fusiform but, rather, maintains a spherical shape. It is unknown whether the generative cell shape may interfere with its function. [ABSTRACT FROM AUTHOR]

• Tropical plant reproductive processes are vulnerable to climate change. • Warming and eCO 2 induced early degeneration of tapetum cells of pollen sacs. • Warming and eCO 2 induced a less differentiated aperture of pollen and compaction of pollen exine. • Warming and eCO 2 induced abnormalities which may hinder the viability of pollen grain. Global climate change is expected to have impacts on the physiological, phenological, and morphological traits of plants. However, the vulnerability of tropical plant reproductive processes in response to climate change events has been poorly studied. Here, we assess if warming and elevated CO 2 compromise the pollen characteristics of Stylosanthes capitata Vogel, a tropical legume forage species. This work was conducted in a Trop-T-FACE (combined Free-Air Temperature Controlled Enhancement and Free-Air Carbon Dioxide Enrichment) facility, where we exposed the plants to four treatments: C (Control -ambient atmospheric carbon dioxide concentration [CO 2 ] and ambient temperature); eCO 2 (increase in [CO 2 ] to 600 ppm and ambient temperature); eT (canopy temperature increase by 2°C and ambient [CO 2 ]); and eCO 2 + eT, a combination of both treatments. We analyzed pollen morphology of samples taken from the different treatments through light microscopy (LM) and scanning electron microscopy (SEM). In addition, pollen viability was analyzed through colorimetry. Based on the histological LM analysis, the tapetum cells of pollen sacs showed early degeneration under eT (72%) added to hypertrophy under eCO 2 (67%) and eCO 2 + eT (90%) treatments. SEM images showed compaction of pollen exine and less distinguishable pollen apertures in the treated plots (eCO 2 , eT , and eCO 2 + eT), possibly, by the early death of the tapetum cells. These morphological abnormalities may hinder the viability of pollen grains, as observed especially in the eCO 2 + eT treatment (%V=64%) that was the lowest in comparison with the Control (71%) and the other treatments (eCO 2 = 69%, eT = 67%). These results indicate that during the reproductive cycle of S. capitata pollen sacs and pollen grains are vulnerable to warming, elevated CO 2 , and their combined effects. [ABSTRACT FROM AUTHOR]

The androecium of Melastomataceae presents notable modifications in its merosity, morphology between whorls and in prolonged connectives and appendages. We carried out a comparative study of six Melastomataceae species to shed light on the developmental processes that originate such stamen diversity. The development of stamens was studied using scanning electron microscopy and histological observations. The stamens of all species studied have a curved shape because they emerge on a plane displaced by the perigynous hypanthium. They are the last flower organs to initiate and therefore their growth is inwards and towards the floral center. Despite the temporal inversion between carpels and stamens in Melastomataceae, the androecium maintains the centripetal pattern of development, the antepetalous stamens emerging after antesepalous stamens. The isomerous androecium can be the result of abortion of the antepetalous stamens, whereas heterostemony seems to be caused by differences in position and the stamen development time. Pedoconnectives and ventral appendages originate from the basal expansion of the anther late in floral development. The delay in stamen development may be a consequence of their dependence on the formation of a previous space so that they can grow. Most of the stamen diversity is explained by the formation of the connectives and their appendages. The formation of a basal-ventral anther prolongation, which culminates in the development of the pedoconnective, does not differ from other types of sectorial growth of the connective, which form shorter structures. [ABSTRACT FROM AUTHOR]

The Swartzia species are commonly known as bloodwood due to the red exudate released from the stem after injury. This exudate has aroused great interest, and an integrative study is essential to describe it in detail. Thus, this work aimed to identify the red exudate's secreting-site in S. flaemingii and S. langsdorffii, and determine if it is a latex or a resin. Samples of the stem bark and the secondary xylem were prepared for histological analysis. Fresh exudates were dissolved in deuterated methanol and analyzed by 1H-NMR; other samples were resuspended in MeOH:H2O (9:1), partitioned with organic solvents and analyzed by direct infusion mass spectrometry. Total phenolic and total flavonoid contents were determined spectrophotometrically, and antioxidant capacity was determined using ferric reducing antioxidant power assay. The results showed that the exudate is a red latex produced by articulated laticifers located among the phloem cells. The latex is composed of sucrose, catechin glucosides, chlorophyll derivatives, and hederagenin-type saponins. Both samples of S. flaemingii and S. langsdorffii presented high amounts of phenolics and flavonoids, as well as a strong antioxidant capacity. The anatomical study showed that the secreting-site of the Swartzia red exudates were laticifers. This finding allows us to exclude other substances such as resin or oleoresin, generally produced by secretory cavities or ducts. Furthermore, since laticifers are rare in Fabaceae, this finding is significant, and represents an essential taxonomic feature. The showy red color is due to the large amounts of flavonoids. This latex probably has a protective role against microorganisms and photodamage. The bioactive potential of this exudate inspires further studies, which may boost the economic importance of Swartzia. [ABSTRACT FROM AUTHOR]

The presence of mucilage cells in plants, studied mainly in vegetative organs, is a condition shared by several taxonomic groups and aspects related to their diversity have been discussed with systematic purposes. This study explores the flower distribution and classification of mucilage cells in Rosales species, with inferences about flower functions. Floral buds from fifty-seven species representing seven of nine families recognized in the Rosales were sampled and processed for light and transmission electron microscopy. Mucilage cells were found in about 40% of the studied species of Cannabaceae, Rhamnaceae, Ulmaceae, and Urticaceae families, whereas no floral mucilage cells were found in species of Elaeagnaceae, Moraceae, and Rosaceae. Mucilage cells were found in the epidermis and internal tissues of many organs of different floral morph types. There is a great diversity of forms of presentation of mucilage in cells, from smaller individualized single cells to very bulky cells and to completely filled mucilage reservoirs. In some cases, cells with mucilage apparently in the cell wall and others with mucilage in the vacuole seem to occur side by side. This diversity challenges the existing classifications of mucilage cells and reinforces the importance of ontogenetic and ultrastructural studies following the path of mucilage in cells in order to propose a more natural classification and to elucidate the evolution of mucilage cells in plants. [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]

PREMISE OF THE STUDY: Although the ovary position is considered a stable character in angiosperms, Melastomataceae species have perigynous flowers in which the ovary varies from superior to inferior. Thus, we investigated the ontogenetic process involved in variation of the ovary position in Melastomataceae. We focused on histogenesis of the floral apex in search of developmental patterns for each type of ovary position. METHODS: Six species in which the ovary varies from superior to inferior were chosen: Henriettea saldanhae, L eandra melastomoides, Miconia dodecandra, Microlicia euphorbioides, Rhynchanthera grandiflora, and Tibouchina clinopodifolia. Buds and flowers were processed for surface and histological examinations. KEY RESULTS: The floral apex changes from convex to concave, resulting in a perigynous hypanthium. Cell divisions in the margins of the floral apex form an annular intercalary meristem that elevates the base of the primordia of almost all whorls. The joint growth of the carpel base with the gynoecial hypanthium originates semi-inferior ovaries in Leandra melastomoides, Miconia dodecandra, and Tibouchina clinopodifolia and inferior ovaries in Henriettea saldanhae. In Microlicia euphorbioides and Rhynchanthera grandiflora, the carpels are not affected by this hypanthial growth; flowers have a superior ovary. CONCLUSIONS: Changes in ovary position of Melastomataceae are due to intercalary meristematic activity, which is one of the main mechanisms for the origin of morphological innovations among plants. Our data illustrate the importance of the intercalary meristems in floral development, and we discuss the implications of this ontogenetic model for understanding the evolution of ovary position in Melastomataceae. [ABSTRACT FROM AUTHOR]

The six distinct gland types described in Mimosoideae anthers vary from simple projections to robust and vascularized structures. The origin of these glands is attributed to an extension of connective. However, except for an illustrative recording of some developmental stages, nothing is known about the origin and gland development, which prevents their correct classification. This study aimed to elucidate the ontogeny of four of the six gland types detected in the anthers of Mimosoideae. The intention was to understand whether the morphological diversity results from different ontogenetic processes. For this, flower buds of various sizes of four Mimosoideae species with different types of glands were collected : Stryphnodendron adstringens (Piptadenia subtype Piptadenia), Tetrapleura tetraptera (Piptadenia subtype Adenanthera), Adenanthera pavonina (Piptadenia subtype Entada), and Pentaclethra macroloba (Pentaclethra type). The samples were processed for surface (scanning electron microscopy) and anatomical analyses (light microscopy). Despite their morphological differences, the glands share a common meristematic origin. They arise from simultaneous divisions in the first three layers of meristematic cells that cover the apical portion of the young anther. After the formation of the protuberance, the developing glands undergo different specialized processes that include (1) elongation of the epidermal cells in Piptadenia subtype Adenanthera and Piptadenia subtype Entada, (2) degradation of central gland cells in Piptadenia subtype Entada, (3) change from a rounded to a triangular shape in the Pentaclethra type, and (4) cell differentiation into a procambial meristem and subsequently into vascular tissue in the Pentaclethra type, resulting in the diversity encountered in the group. Their origin from protodermal and fundamental meristem cells characterizes the anther glands as emergences. Our data indicate a conserved meristematic origin of glands, favoring the hypothesis of homology of these structures and supporting the monophyly of the Mimosoideae clade. [ABSTRACT FROM AUTHOR]

Cavitated secretory trichomes are characterized by a short or absent stalk that is connected to a secretory hollow head. They are rare structures in angiosperms; in Fabaceae, they have been recorded in only seven genera, including Bauhinia s.s. Because B. curvula and B. rufa exhibit glands that are responsible for attracting pollinators to flowers, this study aimed to test whether the cavitated secretory trichomes present in the flowers of these species have an attraction function. As leaf trichomes are commonly related to plant defence, comparative analyses of the morphology, ontogeny, ultrastructure and chemical profile of the secretory trichomes present in flowers and leaves were conducted. It was found that cavitated secretory trichomes are similar in their external morphology and development, regardless of the organ or species analysed. However, interspecific differences were found in the secretion process and chemical profile of the exudate. The differences found in the cavitated secretory trichomes between species indicate that they secrete distinct compounds, whereas the similarities found in these structures between vegetative and reproductive organs indicate that the cavitated trichomes have equivalent ecological functions within a species, probably in plant defence during organ development. [ABSTRACT FROM AUTHOR]

Flowers of Dipterygeae ( Fabaceae, Papilionoideae) exhibit an unusual petaloid calyx. The two adaxial sepals are large and petaloid, and the three abaxial sepals form a three-toothed lobe. The goal of this study was to elucidate the ontogenetic pathways of this peculiar calyx in light of the floral development of the three genera that comprise the tribe. Floral buds of Dipteryx alata, Pterodon pubescens and Taralea oppositifolia were analysed using scanning electron microscopy and light microscopy. The order of bracteole and sepal initiation varies among the species. The androecium is asymmetric. The carpel cleft is positioned to the right or to the left, and is opposite the adaxial antepetalous stamen. The peculiarity of the calyx becomes noticeable in the intermediate stages of floral development. It results from the differential growth of the sepal primordia, in which the abaxial and lateral primordia remain diminutive during floral development, compared with the adaxial ones that enlarge and elongate. Bracteoles, abaxial sepals, petals and anthers are appendiculate, except in T. oppositifolia, in which the appendices were not found in bracteoles or anthers. These appendices comprise secretory canals or cavities. Considering that the ontogenetic pathway for the formation of the petaloid calyx is similar and exclusive for Dipterygeae, it might be a potential synapomorphy for the group, with the presence of secretory canals in the appendices of abaxial and lateral sepals and petals. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 529-550. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the floral ontogeny of Swartzia dipetala, which has peculiar floral features compared with other legumes, such as an entire calyx in the floral bud, a corolla with one or two petals, a dimorphic and polyandrous androecium and a bicarpellate gynoecium. We provide new information on the function of pollen in both stamen morphs and whether both carpels of a flower are able to form fruit. Floral buds, flowers and fruits were processed for observation under light, scanning and transmission electron microscopy and for quantitative analyses. The entire calyx results from the initiation, elongation and fusion of three sepal primordia. A unique petal primordium (or rarely two) is produced on the adaxial side of a ring meristem, which is formed after the initiation of the calyx. The polyandrous and dimorphic androecium also originates from the activity of the ring meristem. It produces three larger stamen primordia on the abaxial side and numerous smaller stamen primordia on the adaxial side. These two types of stamens bear morphologically similar ripening pollen grains. However, prior to the dehiscence of thecae and presentation of pollen in the anther, only the pollen grains of the larger stamens contain amyloplasts. Two carpel primordia are initiated as distinct protuberances, alternating with the larger stamens, in a slightly inner position in the floral meristem, constituting the bicarpellate gynoecium. Both carpels are able to form fruit, although only one fruit is generally produced in a flower. The increase in gynoecium merism probably results in an increase in the surface deposition of pollen grains and consequently in the chance of pollination. This is the first study to thoroughly investigate organogenesis and the ability of the carpel to form fruit in a bicarpellate flower from a member of Fabaceae, in addition to the pollen ultrastructure in the heteromorphic stamens associated with the 'division of labour' sensu Darwin. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173, 303-320. [ABSTRACT FROM AUTHOR]

Background and Aims Moraceae, the family of mulberry and fig trees, displays small homogeneous flowers but extremely diverse inflorescences ranging from simple and branched to complex and condensed. Inflorescences also vary in flower organization in the receptacle, in the degree of flower condensation and in receptacle shape. Thus, the objective of the present study was to compare the inflorescence morphogenesis of Moraceae species, to investigate whether clades with a similar pollination mode share the same patterns of inflorescence development and the developmental stages at which we observe the key changes resulting in the diversified inflorescence architecture that culminates in the Ficus syconium. Methods Inflorescences at different developmental stages were sampled from Brosimum gaudichaudii , Castilla elastica , Clarisia ilicifolia , Ficus pertusa , Maclura tinctoria and Morus nigra and processed for surface and anatomical analyses. Key Results The inflorescence morphogenesis of the studied species is highly variable. The shape of the inflorescence meristem (bulging, hemispheric or elongated), the initiation order and arrangement of flowers along the receptacle and the occurrence of bracts vary between related species. This diversity originates early during inflorescence development. Brosimum gaudichaudii , C. elastica and F. pertusa have flowers enclosed or immersed within the receptacle, although inflorescences begin their development as flat and open structures, as occurs in the other three study species. Conclusion Comparison of the inflorescence morphogenesis in Moraceae species allows us to infer that evolutionary ontogenetic changes driven by pollinators culminate in the enclosure of flowers inside the receptacle, as occurs in the Ficus syconium. [ABSTRACT FROM AUTHOR]

• Myrsine leuconeura is used by ethnic groups to treat infections of the urinary tract. • Essential oil extracted from dried leaves contained mainly (≤ 96.6 %) sesquiterpenes. • Leaf oil stored in idioblasts and secretory canals but not glandular trichomes. • Site/season of collection of leaves did not influence profile of oils qualitatively. • Accumulation of (E)-caryophyllene in leaf oil varied as a function of climate. Myrsine leuconeura Mart. is used by ethnic groups in Brazil to treat infections of the urinary tract, but the chemical profile and morphological characteristics of this medicinal plant have not yet been reported. We have identified the secretory structures of the leaves of this species and determined the influence of geographic site and season of harvesting on the accumulation and chemical composition of the essential oil. A histochemical study was performed using optical and scanning electron microscopy, while essential oils were obtained by hydrodistillation of dried leaves and analyzed by gas chromatography/mass spectrometry. The leaf oils were composed mainly of sesquiterpenes (93.9–96.6%), bicyclogermacrene (12.2–14.7%), (E)-caryophyllene (10.6–14.4%), α-guaiene(7.7–10.1%), spathulenol (6.9–9.6%) and δ -cadinene (6.7–7.2%) being the major constituents. Although site and season of collection did not influence the qualitative composition of the leaf oil, the accumulation of (E)-caryophyllene varied as a function of air temperature and rainfall. The secretory structures in M. leuconeura leaves were identified as peltate-type glandular trichomes, secretory canals, oil cells and mucilage cells. Essential oils were stored in solitary cells and secretory canals, most especially in the latter, but not in the glandular trichomes. This is the first report on the accumulation of essential oils in leaf epidermal cells in the genus Myrsine. [ABSTRACT FROM AUTHOR]

Cannabaceae is a known family because of the production of cannabinoids in laticifers and glandular trichomes of Cannabis sativa. Laticifers are latex-secreting structures, which in Cannabaceae were identified only in C. sativa and Humulus lupulus. This study aimed to expand the knowledge of laticifers in Cannabaceae by checking their structural type and distribution, and the main classes of substances in the latex of Celtis pubescens, Pteroceltis tatarinowii, and Trema micrantha. Such information is also updated for C. sativa. Samples of shoot apices, stems, leaves, and flowers were processed for anatomical, histochemical, ultrastructural, and cytochemical analyses. Laticifers are articulated unbranched in all species instead of non-articulated as previously described for the family. They occur in all sampled organs. They are thick-walled, multinucleate, with a large vacuole and a peripheral cytoplasm. The cytoplasm is rich in mitochondria, endoplasmic reticulum, dictyosomes, ribosomes, and plastids containing starch grains and oil drops. Pectinase and cellulase activities were detected in the laticifer wall and vacuole, confirming its articulated origin, described by first time in the family. These enzymes promote the complete dissolution of the laticifer terminal walls. The latex contains proteins, lipids, and polysaccharides in addition to phenolics (C. sativa) and terpenes (C. pubescens, T. micrantha). The presence of laticifers with similar distribution and morphology supports the recent insertion of Celtis, Pteroceltis, and Trema in Cannabaceae. The articulated type of laticifer found in Cannabaceae, Moraceae, and Urticaceae indicates that the separation of these families by having distinct laticifer types should be reviewed. [ABSTRACT FROM AUTHOR]

Premise of research. Moraceae, the well-known mulberry or fig family, displays small, inconspicuous, diclinous flowers that are very different from many other rosids. One remarkable condition is the gynoecium that is unilocular and uniovulate but composed of two carpels, characterizing a type of pseudomonomery. The pathways that lead to the formation of such a pseudomonomerous gynoecium are insufficiently known. Therefore, the objective of the present study was to elucidate the developmental pathways of this intriguing type of gynoecium in six species representing six of seven tribes recognized in Moraceae: Brosimum gaudichaudii , Castilla elastica , Clarisia ilicifolia , Ficus citrifolia , Maclura tinctoria , and Morus nigra. Methodology. Buds at different stages of development and flowers were processed for surface and anatomical studies. Pivotal results. The gynoecium meristem forms at first a single protuberance in the center of the flower, which then divides, originating two carpels that elongate asymmetrically, but only one initiates an ovule. After elongation of the young carpels, significant differences are found: (1) the two carpels take part in ovary, style, and stigma formation, although only one initiates an ovule in the ovary, and (2) the longer carpel contains an ovule, whereas the smaller carpel is simply a component of the ovary (M. tinctoria). The developed ovary of all species is vascularized by two dorsal traces, attesting to the participation of two carpels. All species except M. tinctoria have two stigmatic branches that, at the time of receptivity, may differ in length. Conclusions. The formation of a pseudomonomerous gynoecium in Moraceae is a condition of carpel dimorphism that manifests itself along an ontogenetic gradient. Such a gradient is evident in the stigma formation, which may involve both carpels, ovulate or not, resulting in symmetrical stigmatic branches or in asymmetrical stigmatic branches, with the shortening or complete absence of one branch. The structure of the pseudomonomerous gynoecium may be the reflection of a balance between the decrease in the number of ovules and the increase and/or maintenance of the equivalent stigmatic surface. [ABSTRACT FROM AUTHOR]

Although in Moraceae the presence of laticifers is considered to be a synapomorphy, little is known about the distribution and morphology of this type of secretory structure in the reproductive organs of its species. Ficus , the largest genus of Moraceae, is characterized by an inflorescence known as syconium and by an obligate mutualistic interaction with pollinating wasps. The objectives of the present study were to evaluate the distribution and morphology of laticifers in syconia of 36 species belonging to different Ficus sections and to survey traits of taxonomic and adaptive value for the group. Syconia containing flowers in a receptive state were collected, fixed and processed for anatomical analysis. All species studied have branched laticifers distributed in the syconium receptacle, in the ostiolar bracts and in the pedicel of staminate flowers. Almost all species show laticifers in the pedicel of shorter-styled flowers. Laticifers also occur in the pedicel of longer-styled flowers in most Ficus sections, except F. curtipes ( Conosycea section) and more than 75% of the studied species of the Americanae section. Laticifers are observed in the sepals of 25 of the 36 species studied and occasionally in the pistil. The presence of laticifers in the pedicel of shorter-style flowers and its absence in the pistil suggest that the distribution of this secretory structure in the fig flower was selected by pressures imposed by the fig-fig wasp mutualism. The laticifers in the pedicel of shorter-styled flowers may confer protection to the developing wasp larvae against natural enemies. However, the absence of laticifers in the pistil of most Ficus species studied was probably selected by the mutualistic relationship with the agaonid pollinating wasps since the latex could interfere with oviposition through the style, with the larval development of the pollinating fig wasps, and the emergence of pollinator offspring from their galls. [ABSTRACT FROM AUTHOR]

Passovia ovata (Pohl ex DC.) Kuijt and Struthanthus polyanthus Mart. are hemiparasitic mistletoes that can grow on Al-accumulating and Al-excluding woody species in the Brazilian Cerrado. It is unclear to what extent this hemiparasitic lifestyle implies facultative Al accumulation by the mistletoes and if so, what are the Al tolerance mechanisms in these species. Using a field-work experiment composed by two facultative Al-accumulating mistletoe species ( P. ovada and S. polyanthus ) infecting Al-accumulating ( Miconia albicans (Sw.) Steud.) and Al-excluding ( Byrsonima verbascifolia (L.) DC.) hosts, we (1) investigated Al accumulation and leaf nutritional status of the mistletoes, (2) characterized the storage sites and the forms of Al accumulated in their leaves, and (3) determined differences in levels of simple organic acids associated with Al detoxification. Leaf nutrients and Al accumulation in mistletoes followed the host elements availability. In both mistletoe species infecting the Al-accumulating host M. albicans , Al was mainly allocated to the phloem fibres, and Al-citrate was the main form of Al. Contrastingly, in the hosts’ leaves Al was present mainly in the form of oxalate complexes. When growing on B. verbascifolia , the Al excluding host, the two mistletoes neither showed symptoms of Al storage nor formation of Al-organic acid complexes. In conclusion, mistletoes growing on Al-accumulating trees tolerate high Al tissue levels by allocating Al in phloem fibres and by its chelation with citrate. [ABSTRACT FROM AUTHOR]

Ovule characters have been shown to be informative at higher taxonomic levels and are therefore of interest in angiosperm systematics. In this study, we aimed to describe the evolution of the outer ovule integument thickness in Melastomataceae and to evaluate its systematic and biological significance. This character was investigated in 137 species, and data from the literature were compiled for 22 additional species, totalling 159 taxa. Integument origin was studied in selected species to clarify whether different conditions were associated with different ontogenetic origins. The most recent common ancestor of Melastomataceae probably had an ovule with a two-cell-layered outer integument. A multilayered outer integument evolved independently at least six times in the family. Moreover, reversals to the two-cell-layered plesiomorphic condition have also occurred more than once. The two-cell-layered and multilayered outer integuments have different ontogenetic origins, enhancing the taxonomic usefulness of this character. The thickness of the outer ovule integument is of systematic significance in Olisbeoideae, Rupestrea, Melastomateae and Miconieae. The multilayered outer integument may have some adaptive significance for Miconieae and Mouriri, groups with endozoochoric fleshy fruits. Evidence of a multiplicative testa was observed in a few species with both types of integuments and it may be associated with a massive seed coat found in large seeds. [ABSTRACT FROM AUTHOR]

• The floral nectary of different lineages of Rhamnaceae were described and compared. • Nectaries of Rhamnaceae have a great morphological diversity. • Floral nectaries originate from the hypanthium and are positioned above the ovary. • The two nectary types we found result of intercalary growth in the intrastaminal area. • The structural origin of nectaries in Rhamnaceae seems to be homologous. Rhamnaceae is a family with small, radially symmetrical flowers, which present nectaries of diverse morphology. Therefore, studies to explain the developmental pathways of this diversity are welcome in understanding the evolutionary biology of this gland. Thus, the objective of the present study was to compare the developing floral nectary of six species of Rhamnaceae belonging to different tribes to check its ontogeny and improve the descriptions of nectary types. Buds and flowers were collected and processed for surface, histological and ultrastructural analyses. The nectaries originate from the hypanthium soon after the gynoecium primordium and are generally positioned above the ovary. All nectaries are structured and vary in terms of surface, shape, and presence of indumentum. Two types of nectary were identified: annular and adpressed. The intensity of intercalary growth in the intrastaminal area has a fundamental role in the hypanthium development and consequently, in the differentiation of nectary types. This phenomenon is also responsible for the different positions of annular and adpressed nectaries in flowers of the Rhamnaceae species studied. We conclude that the origin of nectaries in Rhamnaceae seems to be homologous, despite of their great morphological diversity. Also, this study was successful in testing the value of previous nectary classification, placing the investigated species in the categories already defined for the family. [ABSTRACT FROM AUTHOR]

Melastomataceae have porate anthers. However, unlike Solanaceae and many monocots, in which the poricidal dehiscence depends on the presence of a mechanical layer (often the endothecium), most members of Melastomataceae have no evident specialized layer related to the poricidal opening. The goal of this study was to characterize the tissues that form the apical pore of the anther in 10 Miconia species, which may help to understand the nearly unknown mechanism of anther dehiscence in this genus, considered to be one of the largest and most diverse New World genera. Before anthesis, the apical pores of all of the species are closed by a uniseriate epidermis, the cells of which lack a cuticle. In contrast, the epidermis of the remainder of the anther is covered by a thick, ornamented cuticle. Among Myrtales, the Melastomataceae form a clade with Alzateaceae, Crypteroniaceae and Penaeaceae, almost all of which have anthers with endothecium lacking wall thickenings. In these families, the endothecium may or may not be present in the mature anther, with degenerating cells in the latter case. Anther dehiscence does not depend on the endothecium as the mechanical layer, and this process is still not well understood. However, in the Miconia species studied here, the cuticle may prevent tissue dehydration, and the pore opening seems to be due to the passive process of dehydration taking place only in the pore region due to the absence of the cuticle. [ABSTRACT FROM AUTHOR]

Abstract: The absence of reproductive organs in flowers may ontogenetically arise from inception or by abortion during development. Ficus L., a species-rich genus of angiosperms, is an interesting model for floral developmental studies because of the diversity of sexual systems it contains. This study compares the floral morphology of Ficus citrifolia (monoecious), Ficus religiosa (monoecious), Ficus racemosa (secondarily monoecious), and Ficus hispida (gynodioecious) across development to establish the ontogenetic pathways that result in diclinous flowers. Figs were collected at various developmental stages and were prepared for surface (scanning electron microscopy) and histological (light microscopy) analyses. Dicliny in Ficus is defined by stamen absence from inception in pistillate flowers and either pistil absence from inception (F. citrifolia, F. racemosa and F. religiosa) or by abortion (F. hispida) in staminate flowers. The perianth is formed by a single whorl of sepals, as found in other families related to Moraceae. The gynoecium is tubular during development, a condition that may be related with pseudomonomery. The staminate and neutral flowers in F. hispida develop by similar mechanisms. The diversity in the sexual systems in Ficus results from combinations of different floral morphs (dicliny), which originate from both previously established ontogenetic mechanisms (loss of reproductive organ function by abortion or from inception). These mechanisms act independently of phylogenetic proximity or mechanisms of sex system evolution in Ficus. Other aspects of floral development observed in Ficus are discussed in relation to their systematic position and reproductive biology. [Copyright &y& Elsevier]

Premise of the study: Apocarpy (i.e., free carpels) is considered to be the basal condition for ovary development in angio-sperms. Yet it only occurs in 10% of angiosperm species, of which another 10% are monocarpellate. Most legume flowers are monocarpellate. Species with polycarpellate gynoecia occur in about 15 genera with most representatives in Mimosoideae. In the present study, we analyze legumes with polycarpellate flowers with the aim of improving our understanding of gynoecium evolution. Methods: Flowers of nine legume species from five genera were analyzed using a scanning electron microscope (SEM). Key results: In Leguminosae, carpels usually form as individual primordia or protuberances, Inga congesta differs slightly from this pattern in that the central apex bulges outward before the formation of individual carpel primordia. While legumes usually develop entirely plicate carpels, flowers of Acacia celastrifolia and Inga bella show an intermediate type of carpel morphology with a distal plicate zone and a small proximal ascidiate zone. Carpels in Inga congesta and Archidendron glabrum are sometimes slightly fused at the ovary base. The orientation of carpel clefts seems to reflect the floral symmetry. They are directed to the floral center in mimosoids and caesalpinioids, whereas in Swartzia dipetala carpel clefts are oriented to the adaxial side. Conclusions: Polycarpelly arose at least seven times independently in Leguminosae. The polycarpellate condition appears to be correlated with polyandry, and in most instances, it is accompanied by a profound change in floral organization from a closed to an open system. [ABSTRACT FROM AUTHOR]

Lychnophora salicifolia plants collected from four different places in Brazil (three states: Goias, Minas Gerais and Bahia) revealed a conserved accumulation of vicenin-2, a di-C-glycosyl flavonoid. Quantitative studies by UPLC-MS/MS showed high concentration of vicenin-2 in leaves from sixty specimens of six Lychnophora species. So the tissue distributions of vicenin-2 were evaluated in wild Lychnophora leaves (Asteraceae) by laser based imaging mass spectrometry (IMS) to propose its distributions and possible functions for the species analyzed. Mass spectrometric imaging revealed that vicenin-2, unlike other flavonoids, was produced at the top of the leaves. The combination of localization and UV absorption properties of vicenin-2 suggests that it could act as a UV light barrier to protect the plants, since plants are sessile organisms that have to protect themselves from harsh external conditions such as intense sunlight. [ABSTRACT FROM AUTHOR]

• Secretory structures provide taxonomically important characters in the Adesmia clade. • Secretory cavities are a synapomorphy for the clade that includes the genera Amicia , Poiretia and Zornia. • The presence of secretory (phenolic or mucilaginous) idioblasts is a unifying character for the Adesmia clade. • Environmental factors are likely to have driven the diversification of the secretion and function of glands in the clade. The Dalbergioid Adesmia clade comprises Adesmia DC., Amicia Kunth, Nissolia Jacq., Poiretia Vent., and Zornia J.F. Gmel., all predominantly South American genera except for Zornia which has a pantropical distribution. These taxa share a shrubby or herbaceous habit with glands present on some part of the plant (e.g., stems, leaflets). However, the evolutionary relationships of the full range of secretory structures observed in previous studies are not fully understood. Thus, the goal of this study is to characterize and compare the occurrence and morphology of these glands in leaflets of species of the Adesmia clade. In addition, secretory structures were showed in a phylogenetic context in members of the Adesmia clade. The mature subterminal leaflets of 81 taxa, 79 from the Adesmia clade and two species of the Pterocarpus clade, were sampled from herbaria and living specimens. All genera of the Adesmia clade shared the presence of secretory, mucilaginous idioblasts in the epidermis of their leaflets. Genera of the clade inhabit dry environments, including open areas and highland grasslands (e.g., Savanna, Patagonian steppe, and the Andes). The presence of mucilage in the epidermis of these genera might be an adaptation to reduce water loss through transpiration, providing a hydrophilic interface between the leaflet surface and the environment, protecting plants from intensive radiation. Phenolic idioblasts were found in the mesophyll of Amicia and Zornia. Secretory cavities were observed in Amicia, Poiretia and Zornia. The occurrence of secretory cavities only in these three phylogenetically closely related genera is considered a synapomorphic character as shown by our character reconstruction analysis. The presence of secretory idioblasts is a unifying characteristic of all genera of the Adesmia clade. [ABSTRACT FROM AUTHOR]

• The uncommon polysporangiate (or multilocular) anthers occur in at least 74 species of Melastomataceae within Meriania , Miconia and Microlicia. • The polysporangiate anthers exhibit corrugated thecae with transverse parenchymatous septa partitioning the pollen sacs into several locules. • Non-polysporangiate anthers represent the ancestral trait for the family, and several transitions to polysporangiate anthers were detected. Polysporangiate anthers, i.e., anthers bearing more than four sporangia, are an unusual condition that has been reported in several angiosperm families, including Melastomataceae. The structure of anthers in Melastomataceae and taxa from its sister lineage was investigated in 302 species, which were categorized as polysporangiate or non-polysporangiate based on original and literature data. Additionally, the evolutionary history of the anther type in the family was assessed by stochastic character mapping. The polysporangiate anthers of Melastomataceae exhibit two corrugated thecae with transverse septa of parenchymatous tissue partitioning the four pollen sacs into several small locules, this being the most common type of sporangia multiplication among angiosperms. Despite the fact that non-polysporangiate anthers are the most common character-state observed and have been reconstructed in most ancestral nodes of the phylogeny, a relatively large number of transitions to polysporangiate anthers were estimated in our analyses. One event was detected in Meriania , four events were detected in Miconia , and two (with a reversal) or three independent transitions in Microlicia. Most species with polysporangiate anthers occur in Microlicia , representing about 41 % of the species in the genus. Even though tetrasporangiate anthers are the most common condition among angiosperms, dithecal polysporangiate anthers occur in at least 74 taxa of Melastomataceae, in a unique association with poricidal dehiscence. [ABSTRACT FROM AUTHOR]