The secretory structures of Alismataceae have been described as secretory ducts, laticifer ducts, laticifer canals or schizogenous ducts. However, these terms are not found in the specialized literature, and ontogenetic analyses for the exact classification of these structures are missing. Accordingly, more studies regarding the secretory structures of Alismataceae are necessary to establish homology in the family or in the order. Thus, the aim of this study was to describe the anatomy, ontogeny, distribution in the organs and exudate composition of the secretory structures present in five Alismataceae species in order to determine whether the family has laticifers or secretory ducts. Samples of leaves, flowers and floral apices were processed for anatomical and histochemical analyses by light microscopy. The analysis indicated the presence of anastomosing secretory ducts in all species, occurring in both leaves and flowers. The exudate contains lipids, alkaloids, proteins and polysaccharides, including mucilage. The secretory duct structure, distribution and exudate composition suggest a defense role against herbivory and in wound sealing. The presence of secretory ducts in all species analyzed indicates a probable synapomorphy for the family.
Chrysophyllum (Chrysophylloideae, Chrysophylleae) is the second largest genus in the Sapotaceae. Studies of pollination ecology in this genus are non‐existent, although there are records of entomophily for this family. Considering the lack of detailed studies on pollination ecology and sexual systems in Chrysophyllum species, we investigate the floral morphology and biology and floral visitors of Chrysophyllum marginatum to verify which sexual system is present in the studied population and whether flowers of this species are visited and pollinated by different insect groups. The population of C. marginatum has weak and cryptic gynomonoecy because the plants produce a low percentage of functionally pistillate flowers (4.2%) and these flowers appear to be perfect flowers (hermaphrode). Flowers of C. marginatum are phenotypically, ecologically and functionally generalist because: (a) they are actinomorphic, open and not restrictive in terms of access to floral resources; (b) they are visited by 26 species of insects that are potential pollinators; and (c) among these species several groups can be effective pollinators, mainly bees and flies, according to the most effective pollinator principle. We consider bees and flies to be the main pollinator group of C. marginatum, due to their high visitation rate, richness and intrafloral visiting behavior, and because they especially forage among plant individuals and are able to promote xenogamy. Nectaries were found in the ovary base and osmophores in the petal margins, as floral attractants. For Chrysophyllum, this is the first record of gynomonoecy and for the family this is considered the second record. Chrysophyllum marginatum has generalist and entomophilous pollination, as recorded in other Sapotaceae Neotropical species.
As a major component in plant evolution and reproduction, diaspores are often central to research, not only in botany, but also in zoology, ecology, and limnology. Yet, identification of these structures without the original plant is difficult and hinder the development of research in cases in which the mother plant is not known e.g. in seed bank research or studies with animals (stomach contents, feces, nests) that are associated with diaspores. This guide is a novel resource to the identification of the main species of the Pantanal’s aquatic flora, with high quality photographs of diaspores—except for grass-like Cyperaceae. Diaspores were collected from 53 species (22 families) that occur in different water bodies in the Pantanal. Photographs were organized in plates in alphabetical order of plant families according to APG IV. Among represented taxa are macroalgae (Chara and Nitella), ferns (Salvinia and Marsilea) and Angiosperms (Onagraceae (7), Fabaceae (7), Alismataceae (6), and Polygonaceae (5) presented the highest number of species). This guide also can contribute to insights into community patterns prior to disturbances, carried out through seed bank identification, important in environmental restoration work.
Eichhornia azurea and E. crassipes are morphologically easy to distinguish, however, their seeds are similar and differentiated only by size, which makes their identification difficult, especially when collected directly from the seedbank. We identified characters for distinguish seeds of these species through macrosculpture analyzes of the seed coat (size, shape, epidermal pattern, the structure of the primary and secondary microsculpture, funiculum, hilum, micropyle, raphe), using scanning electron microscopy. The species differ mainly by the secondary sculpture pattern, with perforated in E. azurea and wrinkled with micropapillae in E. crassipes; the external tissue of seed with smooth aspect in E. azurea and irregularly wrinkled in E. crassipes; and raphide crystals in E. crassipes. Our results contribute to taxonomy of the tribe Eichhornieae and future studies on the microsculpture analyzes of the macrophytes seed coat, in a comparative approach to understand ecological and evolutionary aspects.
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