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Abstract Tilia (Malvaceae) is a genus of deciduous trees widespread in the northern hemisphere. Tilia species native to Japan include three endemic species, T. japonica, T. maximowicziana, and T. kiusiana, as well as the more widespread T. mandshurica. Other species were also introduced, the most important being T. miqueliana, brought to Japan with the arrival of Buddhism and planted on temple grounds as Bodaiju. Both historically and at present, Tilia trees are valuable to the people in Japan. Some Tilia trees are considered sacred in both Buddhism and Shinto. They are also prominent ornamental and park trees, albeit less popular in Japan than in Europe. Japanese Tilia spp. are used in the manufacturing of honey, cosmetics, lumber (especially plywood and veneers), and traditional bast cloth. Many Tilia trees are significant hubs in pollinator and mycorrhizal networks, but research on Japanese Tilia ecology is scarce. Despite their importance, Japanese Tilia trees have received less scientific attention in comparison with European Tilia species. The most striking example is T. kiusiana, with virtually no scientific literature regarding the species (save for a series of publications studying its secondary metabolites and potential medical uses). Furthermore, most published resources concerning Tilia in Japan are available only in Japanese, restricting their accessibility. This review seeks to translate, collect, and organize the information available on Japanese Tilia species. By doing so, areas are highlighted where new studies are necessary. A better understanding of these important trees would also be instrumental in their conservation.

Trees of the genus Tilia (Malvaceae) are known to establish symbiosis with ectomycorrhizal (EM) fungi, however, most of what is known about their EM relations is based on few European Tilia species, despite the highest diversity of the genus found in the Asian subcontinent. To the authors’ knowledge, this is the first report on EM fungal communities hosted by Tilia in Japan. Three study sites, on Hokkaido (H) where Tilia was a dominant forest component, Honshu (C) and Kyushu (K) islands where Tilia was extremely rare, were established. From each site 30 root samples of T. japonica were collected after tracing from the trunk, and additional 30 random soil core samples near the traced trees. EM root tips in the samples were subjected to molecular identification of EM fungal species and hosts. The study identified 30 EM fungal lineages (246 OTUs), with 28 lineages (164 OTUs) recorded from T. japonica EM communities. In sites H, C, and K, Tilia communities comprised of 19, 20, and 15 lineages, respectively. 127 EM fungal OTUs were never reported from Japan, and 69 OTUs had no previous records in the UNITE database. Contrarily, about 25% of the recorded OTUs have been exclusively reported from Japan. The observed EM richness hosted by T. japonica exceeded those of cooccurring EM trees as identified from the random soil samples and of other previously studied Tilia species. In each study site, T. japonica was found to exert a consistent “generalist” host effect on its EM fungal communities. About 36% of the EM fungal taxa found in random soil samples were also confirmed in T. japonica root samples, indicating a high connectance of Tilia in the local EM networks. The studied EM communities showed nested structure, with T. japonica as the main contributor to the local community nestedness.