Indirect interactions are pivotal in the evolution of interacting species and the assembly of populations and communities. Nevertheless, despite recently being investigated in plant-animal mutualism at the community level, indirect interactions have not been studied in resource-mediated mutualisms involving plant individuals that share different animal species as partners within a population (i.e., individual-based networks). Here, we analyzed an individual-based ant-plant network to evaluate how resource properties affect indirect interaction patterns and how changes in indirect links leave imprints in the network across multiple levels of network organization. Using complementary analytical approaches, we described the patterns of indirect interactions at the micro-, meso-, and macro-scale. We predicted that plants offering intermediate levels of nectar quantity and quality interact with more diverse ant assemblages. The increased number of ant species would cause a higher potential for indirect interactions in all scales evaluated. We found that nectar properties modified patterns of indirect interactions of plant individuals that share mutualistic partners, leaving imprints across different network scales. To our knowledge, this is the first study tracking indirect interactions in multiple scales within an individual-based network. We show that functional traits of interacting species, such as nectar properties, may lead to changes in indirect interactions, which could be tracked across different levels of the network organization evaluated.

Are parasitoids less likely to find their Lepidoptera hosts on non-native hostplants than native hostplants? We predicted that with longer periods of coevolution between herbivores and the plants they consume, the parasitoids that provide top-down control would be more attuned to finding their hosts on native plants. To test this hypothesis, we collected immature stages of sulfur butterflies (the cloudless sulfur (Phoebis sennae) and the orange-barred sulfur (Phoebis agarithe) over a three-year period (2008-2011) from native and ornamental hostplants in the genus Senna in three different parts of the urban landscape of Miami, Florida, USA. We reared the immature specimens to pupation and either eclosion of adults or emergence of parasitoids and compared the levels of parasitization among the three areas, and among native vs. exotic hostplants. We found, contrary to our prediction, that caterpillars feeding on non-native leguminous hostplant species were more likely to be parasitized than those feeding on native hostplants. We discuss this surprising finding in the light of recent findings in other plant/herbivore/parasitoid systems.

Context-dependence in mutualisms is a fundamental aspect of ecological interactions. Within plant-ant mutualisms, particularly in terms of biotic protection and pollination, research has predominantly focused on elucidating the benefits while largely overlooking potential costs. This notable gap underscores the need for investigations into the drawbacks and trade-offs associated with such mutualistic relationships. Here, we evaluated the role of pericarpial nectaries (PNs) in shaping the dynamics of ant-pollinator mutualisms. Specifically, we investigated whether ants visiting the PN of Palicourea rigida (Rubiaceae) could deter hummingbirds and disrupt pollination, ultimately influencing fruit production. Our research involved manipulative experiments and observation of ant-pollinator interactions on P. rigida plants in the Brazilian savannah. We found that visiting ants can deter hummingbirds and/or disrupt pollination in P. rigida, directly influencing fruit set. However, these results are species-specific. The presence of very aggressive, large predatory ants, such as E. tuberculatum, had a negative impact on hummingbird behavior, whereas aggressive mid-sized ants, such as C. crassus, showed no effects. Our study illuminates the multifaceted aspects of ant-plant mutualisms and underscores the importance of evaluating costs and unexpected outcomes within these ecological relationships.

The structural changes in the secretory cells are important to understand the ontogeny and nectar secretion process from the nectaries. In this study, we investigated the ultrastructural changes during different developmental/secretion stages of extrafloral nectaries (EFNs) of Pithecellobium dulce. The dense cytoplasm with active biosynthesis mechanisms such as ribosomes, mitochondria, large nucleus, and plastids with accumulated starch grains characterized the pre-secretion stage of young nectariferous cells. During the secretory phase, the cytoplasm showed distinct changes associated with endomembrane transport such as the predominant occurrence of Golgi, secretory vesicles, and ER resulting in the subsequent appearance of secretions in the intercellular and subcuticular spaces. Cell wall loosening following the dissolution of middle lamellae leading to the formation of subcuticular spaces was evident during advanced stages of nectar secretion. The characteristic cytoplasmic and apoplastic changes associated with cell death were noticed during the post-secretory stages. The structural evidence from the present study suggests the occurrence of two modes of secretion (merocrine and holocrine) during the early and late stages of secretion in the EFNs of P. dulce.

Plants have evolved inducible defenses that allow them to minimize costs associated with the production of constitutive defenses when herbivores are not present. However, as a consequence, some plants might experience a period of vulnerability between damage and the onset of defense and/or between the cessation of damage and relaxation of defense. Few studies have examined the time course in the inducible protective mutualism between ants and extrafloral nectary (EFN)-bearing plants. None has compared the inducibility of EFNs on vegetative versus reproductive parts or in response to different levels of herbivore damage. Here, we disentangle the inducibility process by evaluating extrafloral nectar production and ant attendance over time, the time course of inducibility on different plant parts, and the time course of inducibility in response to different levels of foliar damage in a Brazilian tree, Qualea multiflora (Vochysiaceae). Using simulated herbivory on leaves and flowers, we found that (a) the production of extrafloral nectar from foliar and floral EFNs, as well as ant attendance, exhibited a lag between the moment of damage and the peak of response, followed by a response peak (usually 24 h after damage) at which the defense remains at its maximum level, then declines to prestimulus levels; (b) the time course of inducibility and the peak activity did not differ between EFNs located in vegetative versus reproductive parts, except for sugar concentration, which was higher in EFNs on vegetative parts; and (c) the time course of inducibility of foliar EFNs depended on damage level. Although considered a cost-saving strategy, inducible defenses can be disadvantageous since they can leave plants vulnerable to attack for extended periods. Our results illuminate the dynamics of the induced response and the underlying mechanisms that might mediate it, ultimately providing new insights into defense strategies employed by plants.

Recent phylogenomic analyses of 997 nuclear genes support the long-held view that the genus Entada is congeneric with Elephantorrhiza. Entada is resolved as monophyletic only if the genus Elephantorrhiza is subsumed within it. The two genera were distinguished solely by relatively minor differences in the mode of dehiscence of the fruits (a craspedium separating into one-seeded endocarp segments in Entada versus a craspedium with the whole fruit valve breaking away from the persistent replum in Elephantorrhiza) and the craspedial fruit type itself provides a shared synapomorphy for the re-circumscribed Entada. Here, we provide a synopsis of Entada, including 11 new combinations in total, for the eight species, one subspecies and one variety previously placed in Elephantorrhiza, as well as a new combination for a subspecies of Entadarheedei Spreng. not previously dealt with when Entadapursaetha DC. was placed in synonymy. These new combinations are: Entadaburkei (Benth.) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadaelephantina (Burch.) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadagoetzei (Harms) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadagoetzeisubsp.lata (Brenan & Brummitt) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadaobliqua (Burtt Davy) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadapraetermissa (J.H. Ross) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadarangei (Harms) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadarheedeisubsp.sinohimalensis (Grierson & D.G. Long) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadaschinziana (Dinter) S.A. O\'Donnell & G.P. Lewis, comb. nov.; Entadawoodii (E. Phillips) S.A. O\'Donnell & G.P. Lewis, comb. nov.; and Entadawoodiivar.pubescens (E. Phillips) S.A. O\'Donnell & G.P. Lewis, comb. nov. We provide a revised circumscription of the genus Entada which now comprises 40 species distributed pantropically, with the greatest diversity of species in tropical Africa. We present a complete taxonomic synopsis, including a map showing the global distribution of the genus and photographs showing variation amongst species in habit, foliage, flowers and fruits. A short discussion about extrafloral nectaries, mainly observed in the Madagascan species, is presented.

Nectar plays important roles in the relationship between plants and other organisms, both within pollination systems and as a defense mechanism. In the latter case, extranuptial nectaries (ENNs) usually attract patrolling arthropods that reduce herbivory. ENNs have been frequently reported within the \"xeric clade\" of Bromeliaceae, but their occurrence in other groups of bromeliads is largely unexplored, especially considering their position, secretory activity and structure. After observing the presence of ants constantly patrolling the inflorescences of Pitcairnia burchellii Mez, we searched for the presence, secretory activity, and structure of ENNs in this species. We also provide a brief review of the occurrence ENNs in Bromeliaceae. The distribution of nectaries was assessed using ant-exclusion experiments, while structural analysis was performed using standard methods for light and scanning electron microscopy. The presence of sugars in the secretion was assessed by thin-layer chromatography and glucose strip tests. Nectaries in P. burchelli are non-structured glands on the adaxial surface of floral bracts and sepals. Bracts and sepals are distinct spatial units that act over time in the same strategy of floral bud protection. Literature data reveals that ENNs might be more common within Bromeliaceae than previously considered, comprising a homoplastic feature in the family. Future perspectives and evolutionary and taxonomic implications are discussed.

UNASSIGNED: The extrafloral nectaries of S. occidentalis were studied structurally and anatomically (at secretory and post-secretory developmental stages). Role of extrafloral nectaries as a common plant-adoptive characteristic in context to diversity and phylogenetic pattern was also speculated while exploring other collaborative evolutionary implications of this plant. Extrafloral nectaries (EFNs) are widespread and evolutionarily labile traits that have repeatedly and remarkably evolved in vascular plants. Morphological descriptions of the EFNs of certain plant species are common in the literature, but they rarely relate morphology with histology, gland distribution and secretory characteristics. Studies relating EFNs features, i.e., morphology and distribution with their differential visitation by insects, viz. ants and the cost of maintenance to the plants are important to understand the evolution of these glands. Therefore, in this study a morphological, anatomical (structure and ultrastructure) and secretory characterization of EFNs occurring on Senna occidentalis L. is made with the implications of gland attributes discussed from a functional perspective. S. occidentalis L. (Caesalpiniaceae) is an economically important species from industrial, medicinal and agricultural perspective. Observations from the result showed that shape of the EFNs (size 1-2 mm) ranged to globular, ovoid-conical, dome-shaped, fusiform or cylindrical with conical tip. The EFNs were sessile, positioned interpetiolar or seated at the base of petiole. Light and transmission electron microscopic studies showed the specific internal structures of the extrafloral nectary. Two developmental stages of the EFNs (secretory and post-secretory) were recognized. Our current understanding of the phylogenetic patterns of EFNs makes them powerful candidates for future work exploring the drivers of their evolutionary origins, shifts, and losses.

UNASSIGNED: Extrafloral nectaries are mainly studied in angiosperms, but have also been reported in 39 fern species. Here we provide a global review of nectaries in ferns, and study their structure, function, and nectar sugar composition in two genera.
METHODS: We searched in the literature and living plant collections of botanical gardens for indications of fern nectaries, studied the morpho-anatomy in the two genera Aglaomorpha and Campyloneurum, and analyzed the total sugar concentrations and ratios of 16 species. Diurnal nectar release was observed with time-lapse photography.
RESULTS: We found evidence for nectaries in 101 species of ferns from 11 genera and 6 families. Most of the nectary-bearing species were tree ferns (Cyatheaceae) and epiphytic ferns of the family Polypodiaceae. Nectaries consisted of cytoplasm-rich parenchyma with large nuclei and an epidermis with or without stomata, were attached to amphiphloic vascular bundles, and released nectar on the lower leaf surface mainly on expanding leaves during the night. Sugar concentrations varied between species (3.8-15.3%) but not between genera, and were sucrose-dominant (3 spp.), sucrose-rich (7), or hexose-rich (3). Under greenhouse conditions, introduced ants, scale insects, and snails fed on the nectar.
CONCLUSIONS: The wide taxonomic distribution, variable morphology, locations, and sugar compositions point to multiple evolutionary origins of fern nectaries. Nectar release in young leaves might attract mutualistic ants to protect leaves against herbivores only during this most vulnerable developmental stage. Even ex-situ, fern nectar is a valuable food source because it attracted several opportunistic animal species. This article is protected by copyright. All rights reserved.

Buds usually possess mechanical or chemical protection and may also have secretory structures. We discovered an intricate secretory system in Ouratea castaneifolia (Ochnaceae) related to the protection of buds and young leaves. We studied this system, focusing on the distribution, morphology, histochemistry, and ultrastructure of glands during sprouting. Samples of buds and leaves were processed following the usual procedures for light and electron microscopy. Overlapping bud scales protect dormant buds, and each young leaf is covered with a pair of stipules. Stipules and scales possess a resin gland, while the former also possess an extrafloral nectary. Despite their distinct secretions, these glands are similar and comprise secreting palisade epidermis. Young leaves also possess marginal colleters. All the studied glands shared some structural traits, including palisade secretory epidermis and the absence of stomata. Secretory activity is carried out by epidermal cells. Functionally, the activity of these glands is synchronous with the young and vulnerable stage of vegetative organs. This is the first report of colleters and resin glands for O. castaneifolia. We found evidence that these glands are correlated with protection against herbivores and/or abiotic agents during a developmental stage that precedes the establishment of mechanical defenses.