The Wamyō Ruijushō is a dictionary compiled in the 10th century (931–938), which aimed to establish correspondences between ancient Chinese and Japanese words, and is considered an important source for ancient Japanese words. Several manuscripts of Wamyō Ruijushō are known, and the composition and texts differ among them. To clarify the usage of Japanese and Chinese names for algae and aquatic plants in Wamyō Ruijushō, the composition and texts under the subheading “Algae” (“Seaweeds” and “Waterweeds”) of the main heading “Vegetables” were compared among the available manuscripts. Based on the existing phylogenetic hypothesis, the original texts of Wamyō Ruijushō were also reconstructed. The sources for the reconstructed original texts were identified, and the validity of the reconstruction was verified by comparing the quotations with the source texts. For the Japanese names in the Wamyō Ruijushō, past identifications to current Japanese names were compared. Particularly, the identification of “sumunori”, which has been identified to Pyropia spp., was revealed to be a freshwater alga in Wamyō Ruijushō.

An unknown Poaceae species was found among weed seed contaminants in livestock feed imported from Australia. The same species was found growing on the sandy coast of Yamaguchi Prefecture, Japan. Based on its morphology and phylogenetic relationships, this species was identified as Vulpia fasciculata, a new alien species in Japan. It is native to Europe, particularly the Mediterranean region, and has become naturalised in South Africa and southern Australia. This species can be distinguished from other Vulpia species in Japan (V. bromoides, V. myuros vars. myuros and megalura, V. octoflora) by having spikelets that disarticulate below the glumes, a pointed callus, a keeled lemma, and three stamens. This species was introduced into Australia and has become a common agricultural weed in southern Australia. Seeds of this species were brought to Japan as contaminants in feed imported from Australia. Specimens collected in Central Honshu in 1989 and 2005 were confirmed as belonging to this species. It is unknown whether this species continues to grow in these locations, but its establishment in Japan likely occurred 20–30 years ago.

Genetic diversity of Malus spontanea (Rosaceae), an endangered tree species that is restricted to a single population growing in the Kirishima Mountains of Kyushu, Japan, was analyzed using microsatellites. Analysis of 307 individuals across native and cultivated populations revealed that the genotypes of 306 individuals were almost identical. Of the entire native population, only nine individuals differed by a single peak at one marker, and one individual by only two peaks at two markers. Only one individual from Isa City had different peaks at multiple markers, and some markers were different at all peaks, so this is thought to be the result of hybridization. Based on these results, almost all existing native individuals of Malus spontanea are estimated to be clones. Further research is needed to clarify the reproductive system within this species and develop a conservation plan to prevent further loss of genetic diversity.

Cytological observation was conducted for the first time on Japanese Antrophyum (Pteridaceae), namely A. obovatum and A. formosanum. The chromosome numbers of the two species were counted as 2n = 240 for the former and 2n = ca. 240 for the latter. Considering the basic chromosome number is x = 30, they are considered as octoploid species. Our study demonstrated the pervasiveness of polyploidy in the genus.

In Hokkaido, northern Japan, Sagittaria pygmaea (Alismataceae) was established in the 1960s–70s in paddy rice fields, considerably expanded until the 1980s, and then declined and became a rare species after the 2000s. However, in primary Japanese taxonomic publications, the species is not reported to be distributed in Hokkaido, probably due to the lack of voucher specimens collected there. In 2024, seven S. pygmaea specimens collected in Hokkaido were discovered in herbaria of Hokkaido University. Their collection localities and environments were consistent with those reported in previous studies, suggesting that these specimens may also be derived from domestic alien populations. Furthermore, one collection locality indicated the northern limit of the species. However, identifying the natural northern limit is difficult because the distribution of the species in northern Japan might be affected by human activities. I searched for S. pygmaea at the northern limit locality in August 2025, but the species could not be found, suggesting that the northern limit population would have declined drastically or disappeared.

Stellaria pentastyla (Caryophyllaceae), collected from the Taplejung district in East Nepal, is reported as a new record for the flora of Nepal. A brief discussion of its distribution, ecology, and diagnostic characteristics is provided.