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The flowers of Peperomia (Piperaceae) are simple, minute, and unique structures within the angiosperms consisting of a rounded bract, two stamens and an ovary, but generally lack taxonomic value at species level. Because of this, morphological characters of vegetative parts have been mainly used for species level taxonomy. There is a need to supplement these vegetative characters with anatomical characters. We selected 17 native Thai species representatives of South East Asian Peperomia to investigate the utility of vegetative anatomical characters for species delimitation, taxon identification, and classification. Stem, petiole, and leaf anatomical characters were studied using standard microscopic techniques. The anatomical characters demonstrated high diversity and supported species identification. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) culstering, Principal Coordinates analysis (PCoA), and Principal Component Anaysis (PCA) were used to investigate patterns in the multivariate anatomical data and identify groupings of value to species classification. Four broad groupings were retrieved and some subgroupings identified. The most important characters that differentiated the species in the multivariate analysis included stem shape (roundness and ridges), petiole indumentum and trichome type, vascular bundle pattern and number, stem pith cavity, mucilage canals, and stem cortex sclerenchyma. These data were further used to prepare anatomical descriptions at generic and species levels and to provide a key to species. [ABSTRACT FROM AUTHOR]

Mangosteen (Garcinia mangostana L.) is widely cultivated for its prized fruit, but its origins are unclear as this crop has not been found in the wild. Seashore mangosteen (Garcinia celebica L.) has been proposed as a candidate ancestral species for the mangosteen male parent in a hypothesized hybridization event, yet the functionality of the male organs in perfect flowers of G. celebica has not been characterized. The objective of this study was to describe pollen development in G. celebica using light, scanning, and transmission electron microscopy techniques. Male gametophyte development led to viable pollen at anthesis. The tapetum was of the secretory type, and it started to degrade following meiosis II, which corresponded to the complete encasement of a callose wall around the microspore tetrad. Pollen viability, demonstrated with 2,3,5-triphenyl tetrazolium chloride (^C) assays, was 68%. An in-vitro pollen germination assay was developed, and the rate of germination was remarkably similar to the viability (68%). Male functionality was clearly confirmed by both the high rate of pollen viability and germination. The occurrence of stigmatic exudates on pistillode and its pollen features are consistent with biotic pollination. The perfect flower of G. celebica is thus a functional male flower. Key words: Garcinia celebica, mangosteen, pollen, pollen germination, tapetum. Le mangoustan (Garcinia mangostana L.) est largement cultive pour ces fruits prises, mais ses origines sont floues, car ce vegetal ne se trouve pas a l'etat sauvage. L'espece Garcinia celebica L. a ete proposee comme espece ancestrale candidate du mangoustan parent male lors d'une hypothetique hybridation, quoique la fonctionnalite des organes males de G. celebica dans des fleurs parfaites n'ait pas ete caracterisee. L'objectif de cette etude etait de decrire le developpement du pollen chez G. celebica par microscopie optique, microscopie electronique a balayage et a transmission. Le developpement du gametophyte male produisait un pollen viable a l'anthese. Le tapetum etait de type secretoire et il commencait a se degrader apres la deuxieme division meiotique, ce qui correspondait au revetement complet des tetrades de microspores par une paroi calleuse. La viabilite du pollen, demontree par le dosage au chlorure de 2,3,5-triphenyl tetrazolium (TTC), etait de 68 %. Un test de germination du pollen in vitro a ete developpe; le taux de germination s'averait remarquablement similaire a celui de la viabilite (68 %). La fonctionnalite male etait manifestement confirmee tant par le taux eleve de viabilite du pollen que de la germination. La presence d'exsudat stigmatique sur le pistillode et les caracteristiques du pollen sont coherentes avec une pollinisation biotique. La fleur parfaite de G. celebica est ainsi une fleur male fonctionnelle. [Traduit par la Redaction] Mots-cles : Garcinia celebica, mangoustan, pollen, germination du pollen, tapetum., Introduction Garcinia celebica L. (syn. G. hombroniana Pierre) is commonly known as 'seashore mangosteen' because of its distribution and morphological characteristics, which resemble that of mangosteen (G. mangostana L.), one [...]