Leaf domatia have received increasing attention in ecology because of their role in plant-animal interactions. However, many previous studies have examined the fauna of domatia only for plants in one region in one season or under cultivated conditions, and have provided only limited insight into their real interactions with the animals inside. I studied the domatium fauna of Viburnum odoratissimum var. awabuki in its natural range of distribution and outside its natural range in the wild and in cultivated plants and in different seasons of the year. I also compared the domatium fauna with the fauna outside domatia of the same plant species, with the fauna inside the domatia of different plant species, and with the fauna on the leaves of surrounding plants with different leaf ornamentation. My findings showed similar composition of mite taxa inside the domatia within the natural range, whether the individuals of Viburnum were wild or cultivated. In comparison, the compositions differed between the inside and outside of domatia between different regions and between different seasons. The findings are a warning for caution in interpreting the results when plant-animal interactions in domatia are studied using plants outside the natural range and based on one-time sampling.

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Although Osmunda japonica and Plenasium banksiifolium often occur sympatrically in southern Kyushu, Japan, no natural hybrids have been reported between them. In this study, hybrids of O. japonica and P. banksiifolium were artificially generated. Using the morphological characteristics of these artificially produced hybrids as a key, possible natural hybrids alongside the parent species were discovered in Kaeda Valley in Miyazaki Prefecture, southern Kyushu. However, all of the natural hybrids were juvenile sporophytes, and no sexually mature natural hybrids have yet been discovered. The finding suggests that natural hybrids between O. japonica and P. banksiifolium are ephemeral, which may partly explain the lack of reports of such hybrids to date.

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Differences in style length among closely related flowering plant species are recognized as a unilateral postmating-prezygotic barrier; species with longer styles prevent pollen fertilization by short-styled congeners. However, little is known about how style length variation within a species affects plant reproduction when exposed to heterospecific pollen. We investigated the relationship between style length in native Oxalis corniculata and hybrid seed formation resulting from interspecific pollination by alien O. dillenii using two O. corniculata populations with large style length variation. We found that the native O. corniculata individuals with longer styles produced hybrid seeds at a lower frequency. In contrast, the effect of style length on seed production following intraspecific pollination conducted as a control treatment was not statistically significant. These results suggest that longer styles of native species can hinder interspecific pollen fertilization owing to physical limitations and mitigate reproductive interference from the alien congener by reducing the cost of ovule loss.

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This is the first report of Taeniophyllum complanatum from Yakushima Island, Amami-Oshima Island, and Okinawa Island, Ryukyu Islands, Japan. The species is rare and was previously considered to be endemic to Taiwan. It is distinguishable from T. aphyllum by its strongly flattened roots, minutely papillate inflorescences and the shape of the fully developed fruit.

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