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Flowering plants have evolved a wide range of strategies to avoid self-fertilization. Although allogamy is common among members of the genus Vanilla, V. lindmaniana is widely known for its ability to self-fertilize, resulting in fruit-set rates of 83–100% following self-pollination. During studies of Vanilla species in the Brazilian Cerrado, populations of V. lindmaniana exhibiting low fruit set under natural conditions were identified. Here, the factors associated with low fruit set in these Cerrado populations were investigated through analyses of floral traits, field observations of pollinators, and experimental treatments designed to assess the breeding system. The flowers of V. lindmaniana are adapted for bird pollination. Although the species commonly produces fruits through facultative autogamy, flowers from the Cerrado populations exhibited a stigma that was separated from the anther by a large rostellum, preventing self-pollination. While autogamy is common in V. lindmaniana, completely allogamous populations may also occur. Such a mixed breeding system may provide advantages over reproductive systems based exclusively on autogamy. Furthermore, it may promote reproductive assurance in the event of pollinator decline or in environments where biotic pollination is irregular or absent.

Background and aims – With more than 40 species, Brazil is the centre of diversity for Vanilla . Despite the species richness, few studies on species boundaries involving Brazilian taxa have been carried out. Consequently, many species have been synonymized under taxa with a wider distribution. This is the case for V. lindmaniana , a species currently synonymized under V. palmarum . While studying the diversity of Brazilian Vanilla , differences between plants from the Amazonia/Cerrado/Pantanal and Caatinga/Atlantic Forest Biomes were recorded. Material and methods – Detailed descriptions based on herbaria specimens and living material of V. lindmaniana and V. palmarum are provided and a morphological comparison is given. Illustrations of both species based on living plants is provided, and their geographic distributions are presented. Key results – Plants occurring in the Amazon, Cerrado, and Pantanal Biomes correspond to V. lindmaniana , while V. palmarum occurs in the Caatinga and Atlantic Forest Biomes. Vanilla lindmaniana is distinguished from V. palmarum by several vegetative and reproductive characteristics, such as the size of leaves and flower structures, and the shape of the fruits. Characteristics associated to pollination strongly differ between both taxa. Vanilla lindmaniana is ornithophilous, while the labellar morphology of V. palmarum suggests pollination by bees. Both species occur as epiphytes on palms: Vanilla lindmaniana predominantly on Acrocomia , Attalea , and Mauritia , while V. palmarum on Elaeis and Syagrus . Both V. lindmaniana and V. palmarum are assessed as Endangered. Conclusion – Appraisal of reproductive and vegetative characteristics from living specimens is crucial in delimitating species boundaries in Vanilla . Species delimitation based on ecological divergencies, plus geographic disjunctions have advanced the current evaluation and understanding of diversity in this economically and ecologically important orchid genus. All evidence reveals that V. lindmaniana is distinct from V. palmarum . Vanilla palmarum is endemic to Brazil, while V. lindmaniana is widely distributed throughout South America.

Background and aims – With 40 species, Brazil is the centre of diversity for Vanilla . Frederico Carlos Hoehne described eight Vanilla species for the Brazilian flora, including Vanilla schwackeana , an obscure taxon currently assumed to be a synonym of V. planifolia . While studying Neotropical Vanilla , plants were found in gallery forests of the Vale do Rio Doce region, Minas Gerais, south-eastern Brazil. Based on the examination of the protologues of the Brazilian species, in addition to the study of herbarium specimens, it was verified that the plants correspond to the rare V. schwackeana . Material and methods – A redescription of V. schwackeana is provided, and a morphological comparison with other Neotropical taxa is presented. An illustration of V. schwackeana based on living specimens is provided, and its geographic distribution is presented based on recent findings. The position of V. schwackeana within Vanilla is discussed based on both morphological data and a molecular phylogeny. Key results – Vanilla schwackeana is distinguishable by its pseudopetiolate leaves, by its largely elliptic to obelliptic leaf blades with attenuate base and acuminate apex, by its apical racemes with small flowers, by its yellow labellum with white undulate-crenulate margins, and by its papillous appendages on the apical portion of the labellar crest. Both morphological and molecular data suggest a close relationship of V. schwackeana with V. appendiculata , V. hartii , and the Brazilian endemic V. rupicola . Based on current data, V. schwackeana is assessed as Critically Endangered. Conclusion – Integrative taxonomy was crucial to understand the identity and species boundaries of V. schwackeana . The V. appendiculata/V. schwackeana /( V. hartii / V. rupicola ) clade comprises an unrecognized infrageneric Vanilla group. It seems plausible that the formation of a new infrageneric group will be necessary. As the habitat of V. schwackeana has been devastated by iron ore extraction, conservation strategies for this Brazilian endemic species will be necessary.

Background and aims – The Brazilian biomes include the world’s greatest diversity of Vanilla . This richness has required studies on species boundaries, as many taxa have been described or erroneously synonymized. This is the case for V. argentina , a species described from the Dry Chaco synonymized under V. chamissonis . While studying the diversity of Neotropical Vanilla , differences between plants from the Cerrado/Dry Chaco, the Atlantic Forest, and the Caatinga became evident. Material and methods – Descriptions of members of the Vanilla chamissonis clade, i.e. V. argentina , V. calyculata , and V. chamissonis are provided and a morphological comparison is given. An identification key and illustrations are provided. Geographic distributions and the reproductive strategies are presented. The phylogenetic relationships among the members of the V. chamissonis clade are discussed based on an ITS (nrDNA) phylogeny. Key results – Plants occurring in the Cerrado and Dry Chaco correspond to V. argentina , while V. calyculata and V. chamissonis occur in dry environments and in the Atlantic Forest, respectively. Vanilla argentina is distinguished from the other species by several characteristics, such as the size of the leaves and the flower structures, and fruit features. Vanilla argentina is self-compatible, while V. calyculata and V. chamissonis have a reproductive system based on late-acting self-sterility. All three species are assessed as Endangered. The identities of V. carinata , V. gardneri , and V. vellozii are clarified. The name V. argentina is revalidated. Conclusion – The evaluation of vegetative and reproductive characteristics of both living and dried specimens is crucial to understand the species delimitation among Vanilla . All evidence reveals that V. argentina is distinct from V. chamissonis . Vanilla chamissonis is endemic to Brazil, while V. argentina is distributed throughout Brazil, Argentina, and Paraguay. Vanilla calyculata occurs in dry regions of South and Central Americas. The Vanilla chamissonis clade comprises a lineage of three species within the Vanilla pompona group.

The orchid subtribe Laeliinae has an assemblage of morphologically diverse taxa. The diversity in floral morphology of its members can be explained in terms of pollination ecology in that this subtribe contains both entomophilous and ornithophilous species. Given the wide range of pollinators, one would expect to find considerable differences in morphology of the floral nectaries. Fully developed nectaries appeared to be entirely non-functional in some taxa. The aim of this work was to compare the micromorphology of the inner nectary spur in selected representatives of Laeliinae in order to ascertain which structural features improve or reduce nectar secretion, and thereby contribute towards the evolutionary success of this subtribe. Here, we investigate the nectary structure of 48 species representing the genera Prosthechea , Encyclia, Epidendrum and Dinema . Of these, the nectary of Encyclia was of the narrow-tubular form (cuniculus-type), that of Prosthechea and Dinema was short and sac-like, whereas both nectary types were present in Epidendrum , the former type being the more common. Whereas the nectary of Dinema contained nectar, this was either absent or present in nectaries of the other three genera. Statistical analyses of the morphological and micromorphological characters of the nectary revealed that the probability of nectar being present was lower for the long, tubular nectaries (e.g. Encyclia and Epidendrum ), whereas most Prosthechea spp. investigated, as well as Dinema , possessed sac-like, functional nectaries. Also, all investigated taxa, irrespective of the presence of nectar, shared a thick cuticle and thick epidermal and subepidermal cell walls (in the secretory layer). Analyses also showed that the probability of nectar being present increased with an increase in the thickness of the secretory layer. Furthermore, there was also a greater probability of the epidermal cells lining functional nectaries having a smooth cuticle. The occurrence, or otherwise, of nectar may indicate that the secretory capacity of this group of orchids is plastic, and not limited by structural constraints, thus allowing for the relatively easy turning on and off of the secretory process.

Background and aims – Brazil has more than 40 species of Vanilla . Some taxa have been considered to be obscure since they are known only from the type specimen. This is the case of some south-eastern Brazilian species such as V. dubia and V. dungsii . While studying the diversity of Brazilian Vanilla , plants of an unidentified species were found in Ubatuba, São Paulo, Brazil. After flowering, it was confirmed that the species corresponded to the obscure V. dubia . Material and methods – A redescription of V. dubia is provided and a morphological comparison with the related taxa V. dungsii and V. paulista is presented. An illustration of V. dubia is provided, and its geographic distribution is presented. The identity of the enigmatic V. dungsii is also clarified based on holotype examination and on images of living specimens. Key results – Vanilla dubia is recognized by its coriaceous leaves with prominent vascular bundles in transverse section, by its white 3-lobed labellum with yellow lobes and undulate-crenulate margins, and by its tuberculate appendages on the apical portion of the labellar crest. Morphological characteristics suggest a close relationship of V. dubia with V. dungsii and V. paulista.Vanilla dubia occurs in the Dense Ombrophilous Forest, while V. paulista occurs in the Semi-deciduous Mesophytic Forest, and V. dungsii is endemic to the Dense Montane Ombrophilous Forest. Based on current data, V. dubia is assessed as Endangered. Conclusion – Evaluation of vegetative and reproductive characters from living and herbaria specimens is crucial to understanding the identity and species boundaries of Vanilla . The data presented here show that the species occurring in the Atlantic Forest, V. dubia and V. dungsii , are more closely related to each other than to V. paulista , which occurs in Semi-deciduous Mesophytic Forests. A proposal to change the status of V. dungsii as a subspecies of V. dubia can be further considered.

Several studies have reported stingless Meliponini bees gathering hairs from the labella of Maxillaria spp., including M. ochroleuca, a member of the M. splendens alliance. Such hairs usually contain food materials and are thought to have nutritional value. The papillose labella of representatives of the Maxillaria splendens alliance, however, bear scattered, simple 1-5-celled uniseriate trichomes (hairs) that lack food materials. By contrast, here, as well as polyphenolic compounds, typical labellar papillae usually contain small quantities of starch, protein, and minute droplets of lipid, the last probably involved in the production of fragrance. Towards the labellum apex occur elevated groups of papillae that lack food materials, but contain volatile compounds, probably fragrance precursors. In the past, the terms ‘trichomes’ or ‘hairs’ and ‘papillae’ have been used interchangeably, causing some confusion. Since the trichomes, however, unlike the papillae, are easily detachable and can fragment, it is most likely they, not the papillae, that have previously been observed being collected by bees, but their poor food content indicates that they do not function as food-hairs. Even so, our field observations of M. ochroleuca reveal that stingless bees scrape polyphenol-rich labellar tissue and possibly use this material to produce a resinous, complex, heterogeneous substance commonly referred to as ‘bee glue’, used for nest construction and repair.

, the largest genus of Neotropical orchids, contains both nectar-secreting and nectarless species. Here, we compare the fine structure of the inner floral spur, termed the cuniculus, in nectariferous ( , ) and seemingly nectarless ( , , ) species. This is the first time for such a detailed investigation of cuniculus structure to be undertaken for Our aim was to characterize features indicative of secretory activity and to ascertain whether flowers presumed to be nectarless produce alternative pollinator food-rewards. The cuniculus is formed by fusion of the basal part of the labellum and column and extends alongside the ovary and transmitting tract. Our study indicates that all investigated species produce nectar or nectar-like secretion to varying degrees, and no alternative pollinator food-rewards were observed. Even though macroscopic investigation of presumed rewardless species failed to reveal the presence of secretion within the cuniculus, close observations of the cells lining the cuniculus by LM, SEM, and TEM revealed the presence of cuticular blisters and surface material. Moreover, the similarity of both the thick tangential cell walls (with the exception of ) and organelle complement of cuniculus epidermal cells in both copiously nectariferous species and those producing only small quantities of surface secretion confirmed the presence of secretory activity in species generally regarded to be rewardless. The secretory character was particularly obvious in the cells of the cuniculus of but also in and since electron-dense cytoplasm and mitochondria, ER and secretory vesicles were abundant. Furthermore, cell wall protuberances occurred in , which was indicative of intense transmembrane transport. This investigation highlights the need to examine more closely whether spp. considered to lack food-rewards based solely on macroscopic examination really are rewardless and deceptive.

Spiranthinae orchids are known for being self-compatible and offering nectar as a reward. Although data on their pollinators are scarce, members of this tribe are mostly pollinated by bees, hummingbirds and moths. Some of them even reproduce through facultative self-pollination. Nothing is known about the pollinators and reproduction system in Pteroglossa . Based on records on flowering phenology, floral morphology, reward production, pollinators and breeding system, this paper aims to study the reproductive biology of two Pteroglossa spp. Both species offer nectar as a resource and are pollinated exclusively by diurnal Lepidoptera at the studied areas. Nectar is produced by two glandular nectaries, and is stored in a spur. Pollinaria possess a ventrally adhesive viscidium that is deposited on the basal portion of butterfly proboscides. Both species are self-compatible but pollinator-dependent. The reproductive success is low when compared to other Spiranthinae. Although no evident mechanical barrier to avoid self-pollination or geitonogamy was identified, the erratic behavior of the butterflies, with their infrequent visits to only one flower per inflorescence, contributes to an increased fruit set produced through cross-pollination. The presence of ventrally adhesive viscidia in Spiranthinae is responsible for greater pollinator diversity when compared to bee-pollinated Goodyerinae with dorsally adhesive viscidia, adapted to attach to bee mouthparts.