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Androdioecy is the rarest sexual system among plants. The majority of androdioecious species are herbaceous plants that have evolved from dioecious ancestors. Nevertheless, some woody and androdioecious plants have hermaphrodite ancestors, as in the Annonaceae, where androdioecious genera have arisen several times in different lineages. The majority of androdioecious species of Annonaceae belong to the Neotropical tribe Malmeeae. In addition to these species, Pseudoxandra spiritus-sancti was recently confirmed to be androdioecious. Here, we describe the morphology of male and bisexual flowers of Pseudoxandra spiritus-sancti, and investigate the evolution of androdioecy in Malmeeae. The phylogeny of tribe Malmeeae was reconstructed using Bayesian inference, maximum parsimony and maximum likelihood of 32 taxa, using DNA sequences of 66 molecular markers of the chloroplast genome, sequenced by next generation sequencing. The reconstruction of ancestral states was performed for characters associated with sexual systems and floral morphology. The phylogenetic analyses reconstructed three main groups in Malmeeae, (Malmea (Cremastosperma, Pseudoxandra)) sister to the rest of the tribe, and (Unonopsis (Bocageopsis, Onychopetalum)) sister to (Mosannona, Ephedranthus, Klarobelia, Oxandra, Pseudephedranthus fragrans, Pseudomalmea, Ruizodendron ovale). Hermaphroditism is plesiomorphic in the tribe, with four independent evolutions of androdieocy, which represents a synapomorphy of two groups, one that includes three genera and 14 species, the other with a single genus of seven species. Male flowers are unisexual from inception and bisexual flowers possess staminodes and functional stamens. Pseudoxandra spiritus-sancti is structurally androdioecious., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Premise of the Study: The grass subfamily Anomochlooideae is phylogenetically significant as the sister group to all other grasses. Thus, comparison of their structure with that of other grasses could provide clues to the evolutionary origin of these characters., Methods: We describe the structure, embryology, and development of the flower and partial inflorescence of the monotypic Brazilian grass Anomochloa marantoidea. We compare these features with those of other early-divergent grasses such as Pharus and Streptochaeta and closely related Poales such as Ecdeiocolea., Key Results: Anomochloa possesses several features that are characteristic of Poaceae, notably a scutellum, a solid style, reduced stamen number, and an ovary with a single ovule that develops into a single indehiscent fruit. Interpretation of floral patterning in Anomochloa is problematic because the ramification pattern of the florets places the bracts and axes in unusual positions relative to the primary inflorescence axis. Our study indicates that there is a single abaxial carpel in Anomochloa, probably due to a cryptic type of pseudomonomery in Anomochloa that resembles the pseudomonomery of other grasses. On the other hand, the Anomochloa flower differs from the "typical" grass flower in lacking lodicules and possessing four stamens, in contrast with the tristaminate condition that characterizes many other grasses., Conclusions: Using the median part of the innermost bract as a locator, we tentatively homologize the inner bract of the Anomochloa partial inflorescence with the palea of other grasses. In this interpretation, the pattern of monosymmetry due to stamen suppression differs from that of Ecdeiocolea.

Extrafloral nectaries are nectar-secreting structures that are especially common among the woody flora of the Brazilian cerrado, a savanna-like vegetation. In this study, we provide morphological and anatomical descriptions of extrafloral nectaries (EFNs) occurring on vegetative and reproductive organs of several plant species from the cerrado, and discuss their function and ecological relevance. We describe the morphology and anatomy of EFNs of 40 species belonging to 15 woody families using scanning electron microscopy and light microscopy. We categorise EFNs following a structural-topographical classification, and characterise the vascularised and complex nectaries, amorphous nectaries and secretory trichomes. Fabaceae, Bignoniaceae, Malpighiaceae and Vochysiaceae were the plant families with the majority of species having EFNs. Ten species possess more than one morphotype of gland structure. Observations and experimental field studies in the cerrado support the anti-herbivore role of EFN-gathering ants in this habitat. Additional morphological studies of EFNs-bearing plants, including other growth forms (e.g. herbs and lianas), are being undertaken and will hopefully cast further light on the ecological relevance of these glands in the cerrado, especially with respect to their attractiveness to multiple visitors.