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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]

The synstigma is a structure formed by clusters of two to several stigmas, whether in the same or between different flowers. Although rare in angiosperms, synstigmas are found in c. 500 out of the c. 750 Ficus spp. (Moraceae). This floral structure is associated with fig-fig wasp pollinating mutualism. The synstigma structure and pollen tube pathways were studied in six Ficus spp. from Ficus section Americanae to test the hypothesis that the synstigma allows pollen grains deposited on a stigma to emit pollen tubes that can grow laterally and fertilize surrounding flowers. Syconia containing recently pollinated stigmas were collected and dissected, and the stigmas were processed for analyses with light and scanning and transmission electron microscopy. The arrangement of the synstigmas across species can be spaced or congested, with the number of stigmas per synstigma ranging from two to 20. Contact between the stigmas in a synstigma occurs by the intertwining of the stigmatic branches and papillae; their union is firm or loose. The pollen tube grows through live cells of the transmitting tissue until reaching the ovule micropyle. Curved pollen tubes growing from one stigma to another were observed in five out of the six species studied. The curvilinear morphology of pollen tubes probably results from competition by pollen between the stigmas composing a synstigma via chemotropic signals. The synstigma appears to be a key adaptation that ensures seed production by flowers not exploited by the fig wasps in actively pollinated Ficus spp. [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]

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]

Premise of the Study: This study details the unusual synorganization of the staminate flower in wind‐pollinated urticalean rosids to add the missing pieces that complete the puzzle of the explosive mechanism of pollen release in this group. Methods: Flower buds and flowers were analyzed using light and scanning electron microscopy. Key Results: The pistillode, stamens, and sepals form a floral apparatus that explosively releases pollen to be carried by the wind. The anthers dehisce when the stamens are still inflexed on the floral bud and are enveloped by the sepals and supported by an inflated pistillode. The distension of the filaments presses the pistillode, which decreases the pressure exerted on the anthers by releasing the air accumulated internally through its apical orifice. The extended filaments and the dehiscent free anthers move rapidly outward from the center of the flower. This movement of the filaments is then blocked by the robust basally united sepals, which causes a rapid inversion of the anther position, thus hurling the pollen grains far from the flower. The pollen grains are released grouped by the mucilage produced in high quantity in the cells found in all floral organs. Conclusions: The anatomical structure of the pistillode and the finding of mucilaginous cells are the main features that help in the understanding the explosive mechanism of pollen release in urticalean rosids. The pistillode can be considered an exaptation because it was evolved later to provide a new role in the plant, optimizing male fitness. [ABSTRACT FROM AUTHOR]

In this study, we reassessed the morphology and distribution of laticifers present in the inflorescences of nine Moraceae and three Urticaceae species and compared the substances found in their latices. Reproductive meristems and inflorescences at different developmental stages were collected, fixed and processed for light microscopy analysis. In Moraceae, laticifers occur in almost all inflorescence organs. In Urticaceae, the presence of laticifers in the inflorescence axis and sepals is a novelty, since the family is characterized by having laticifers only in the bark. The laticifers of Moraceae and Urticaceae show a thin pectocellulosic cell wall and are articulated and branched, although they are currently classified as non-articulated branched in Moraceae and non-articulated unbranched in Urticaceae. The latex contains proteins and alkaloids. Lipids are common in Moraceae latex, whereas phenolic compounds occur in the Urticaceae latex. Polysaccharides occur in the majority of the species studied, an unprecedented finding for the group. Thus, we found that the non-articulated type of laticifer may not consist of a synapomorphy for Moraceae and Urticaceae. Moreover, the laticifer branching in the inflorescences of Urticaceae indicates that its distribution and ramification as acknowledged in the literature (restricted to the bark and unbranched) should be reevaluated and may not constitute synapomorphies for this family either. The adaptive value of laticifers for Moraceae and Urticaceae is high, since they occur widely in the plant body of their representatives. The presence of proteins and alkaloids in the latex and the absence of starch grains are probably conserved traits in the urticinean rosids. [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 THE STUDY: Fig trees (Moraceae) have remarkable enclosed inflorescences called figs or syconia. The flowers are pollinated by host-specific fig wasps that enter the fig to lay their eggs. This nursery pollination system is one of the most studied of tropical mutualism interactions, but the source of the volatiles that attract fig wasps to their specific host figs has not been confirmed. The fragrance is the basis of host selection and, therefore, of reproductive isolation among sympatric Ficus species. This study locates and characterizes the glands likely to be responsible for pollinator attraction and also protection from herbivory in the figs of nine Ficus species representing all the major lineages w ithin the genus. METHODS: Figs with receptive pistillate flowers were examined using light and scanning electron microscopy. Tests for histolocalization of substances were employed to detect glandular activity throughout the figs. KEY RESULTS: A great diversity of glands is found throughout the fig, and for the first time, the sites producing fragrances are identified. Scent glands are present on the ostiolar bracts and the outer layers of the fig receptacle. Laticifers and phenolic-producing idioblasts, epidermis, and trichomes associated with fig protection occur on the ostiolar bracts, the fig receptacle, and floral tissues. CONCLUSIONS: The volatiles produced by glands on the ostiolar bracts are candidate sources for the long-distance attraction of pollinator fig wasps. Scent glands on the outer layers of the receptacle may also play a role in chemical perception of the figs or may be related to their protection. The high cost to the plants if the figs are eaten and the temperature conditions required for nursery pollination are likely the factors that led to the selection of phenolic glands and laticifers during the group's evolution. [ABSTRACT FROM AUTHOR]

The processes allowing evolutionary transitions in resources used by parasitic wasps are largely unknown. Microhymenopteran communities associated with figs could provide a model system to investigate such transitions. We investigate here a species of genus Idarnes. The larvae generally develop as inquilines of the pollinating wasp larvae. However, in figs where the parasitic pressure is high, eggs are laid in developing seeds. These eggs turn into small males. This is the first report of seed consumption by a fig wasp. Using an alternative resource to produce small males could provide a pathway to select for increased ability to use this resource and hence provide an intermediate step for evolving the capacity to use new resources. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 9–17. [ABSTRACT FROM AUTHOR]

The mulberry and fig family (Moraceae) has tiny flowers with a single whorled or absent perianth and inner whorls with a reduced number of organs. Relevant questions about this reduced floral structure still remain unresolved. Thus, we studied the ontogenic processes that culminate in such a reduced flower, as well as the close relationship between the floral envelope and the androecium in Brosimum gaudichaudii , Castilla elastica , Clarisia ilicifolia , Maclura tinctoria and Morus nigra . Flower buds and flowers were processed for surface (scanning electron microscopy) and anatomical (light microscopy) analyses. The perianth consists of sepals, except the flowers of B. gaudichaudii and C. elastica (staminate), in which the perianth is lacking. The staminate flower of B. gaudichaudii exhibits a bracteole enveloping the stamens. In monochlamydeous flowers the order of sepal initiation is helical or asynchronous. No petals are initiated. The calyx displays different degrees of synorganization being united only basally or along its entire extension. The sepals can have tector and glandular trichomes or only tector trichomes. Laticifers, phenolic and crystalliferous idioblasts occur in the sepal mesophyll. Stamens initiate concomitant with the pistillode in B. gaudichaudii and after initiation of the pistillode in M. tinctoria and M. nigra. In C. ilicifolia there is no pistillode and the stamens initiate after the sepals. The stamens show variation in filament shape and connective structure. The filament is inflexed in M. tinctoria and M. nigra and straight in the other species, although these structures are anatomically similar. The connective is expanded (except in M. nigra and C. ilicifolia ) and has phenolic idioblasts. We conclude that the tiny flowers of these species result of two distinct ontogenetic pathways: absence of organs from the inception and by abortion, mechanisms that act to decrease the number of floral whorls as well as the number of organs in each whorl. [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]

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]