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Pera is a neotropical genus that currently belongs to the family Peraceae. This circumscription resulted from an inclusion of the Rafflesiaceae between the old tribe Pereae and all other Euphorbiaceae, and wherein Pereae was elevated to family rank making Euphorbiaceae monophyletic again. These changes are necessary although Rafflesiaceae are holoparasitic with extremely reduced vegetative bodies and large flowers while Peraceae and Euphorbiaceae have well developed vegetative parts and reduced flowers. As the embryology of Peraceae was poorly known, and embryological processes are conservative, we studied the embryology of Pera glabrata, searching for similarities between Peraceae, Rafflesiaceae, and Euphorbiaceae that could support this grouping. Usual methods of light microscopy and scanning electron microscopy were utilised. The results show endothecium with reversed-T-shaped cells, prismatic crystals in the tapetum, and disintegrated aerenchymatous septum in the mature fruit as unique features for Peraceae and possibly apomorphies for the family. In addition to the unisexual flowers, porogamous fertilization is present and one ovule per carpel which may support the Peraceae-Rafflesiaceae-Euphorbiaceae clade. The comparative approach also suggests possible (syn-)apomorphies for linoids and phyllanthoids, only linoids, Rafflesiaceae, Euphorbiaceae, and Ixonanthaceae. The presence of a placental obturator found previously unknown in Peraceae emerged as a possible synapomorphy for the euphorbioids (including Ixonanthaceae, Linaceae, Phyllanthaceae, Picrodendraceae, Peraceae, Rafflesiaceae, and Euphorbiaceae), which appeared in a common ancestor of the group and has been lost in Rafflesiaceae. [ABSTRACT FROM AUTHOR]

In various monocotyledons, there are basally blindly ended stem vascular bundles, which never connect to the vascular bundles of roots. These blindly ended vascular bundles seem to be unsuitable for transferring water in terrestrial plants. In the present study, we aim to clarify the trace of the blindly ended stem vascular bundles in whole plants, and consider the evolutional process for holding such vascular bundles in the stem. We examined a whole stem vasculature of Eriocaulon taquetii (Eriocaulaceae, monocotyledons) by observation of serial transverse sections, cut by a manual rotary microtome, and viewed under an epifluorescence microscope. Our investigation revealed a threedimensional reconfiguration of the scape vasculature and detected basipetally developing and basally blindly ended vascular bundles, originated from involucral bracts and arranged with acropetally developing vascular bundles alternately in the scape internode. The basipetally developing and basally blindly ended vascular bundles, which originate from the primodia of foliar organs, have been reported in various commelinids. The characteristic vascular bundles would be homologous and presumed to be a synapomorphy of commelinids. These vascular bundles are considered to be a relic characteristic from ancestral semiaquatic plants of monocotyledons.