Aim Modern species invasions result in the global reshuffling of regional floras, but biogeographical biases in floristic exchanges (origin effects) are underexplored. We compared habitat‐level invasion patterns in two environmentally similar regions, and ask whether plant exchanges are also similar or if one region largely invades the other. Location Eastern North America (ENA) and East Asia (EAS). Methods We compiled a new dataset of the 1293 naturalized (i.e. non‐native, self‐sustaining) and invasive (i.e. spreading) plant taxa in EAS, including the habitats they invade and their native distributions. We tested for biases by biogeographical origin, growth form and habitat in EAS invasions, and compared them with those for ENA. Results EAS contains 51% fewer naturalizations than ENA, but with a similar biogeographical representation. However, invasions in each region show large differences in biogeographical affinity, taxonomic representation and habitat. Invasions in ENA are biased from East Asia (29% invasive), while invaders in EAS come from a fairly uniform set of major temperate regions. Taxonomically, 54% of Asteraceae naturalizations in EAS are invasive compared with only 16% in ENA. Open habitats are highly invaded in both regions (75% of invasions), but forests are significantly more invaded in ENA than EAS (29% vs. 9%). Reciprocal invasions are asymmetric: EAS contributes more woody invaders to ENA than expected (56% woody, P < 0.001), while in EAS nearly all (91%) invaders from ENA are herbaceous. Main conclusions Although they represent regions of similar temperate environments, the origin, taxonomy and habitat affinities of plant invaders in EAS and ENA floristic regions are strongly contrasting. These differences are robust to differences in introduction effort when the invasiveness of species once naturalized is considered. We suggest these patterns support a historical perspective of invasions that invokes differences in regional selection pressures that pre‐adapt certain floras for invasion into particular environmental conditions.

Proto‐Araceae, the earliest diverged lineage within the family Araceae, includes two subfamilies, Gymnostachydoideae (one species) and Orontioideae (eight species). Based on an extensive sampling (a total of 198 accessions) of six chloroplast non‐coding regions (5799 aligned sites), we assessed phylogenetic relationships among the genera and species within subfamily Orontioideae and estimated the timing of intercontinental disjunct events in the Northern Hemisphere. Overall phylogenetic relationships among the genera were consistent with results from previous studies, but several new important findings were discovered, primarily within Symplocarpus Salisb. ex W. P. C. Barton. First, two major lineages within Symplocarpus were identified: one lineage included S. foetidus (L.) Salisb. ex W. Barton, S. nabekuraensis Otsuka & K. Inoue, and S. renifolius Schott ex Tzvelev (Japan), whereas the other included S. nipponicus Makino, S. egorovii N. S. Pavlova & V. A. Nechaev, and S. renifolius (Korea). Symplocarpus renifolius in Japan was tetraploid and closely related to the tetraploid S. foetidus in eastern North America. Populations of S. renifolius in Korea were confirmed to be diploid (2n = 30) and shared the most recent common ancestor with the other diploid species, S. nipponicus. Second, two recently described species, S. nabekuraensis and S. egorovii, were deeply embedded within S. renifolius in Japan and Korea, respectively, and their distinct taxonomic status requires further assessment. Finally, two intercontinental disjunction events in the subfamily, one in Lysichiton Schott between eastern Asia and western North America and the other in Symplocarpus between eastern Asia and eastern North America, were estimated to be between 4.5 and 1.4 million years ago (Pliocene and Pleistocene) and between 1.9 and 0.5 million years ago (Pleistocene), respectively.

To elucidate the origin and migration history of the "Mansen elements," a group of temperate grassland plants mainly distributed in northeastern Asia, phylogeographic analyses based on chloroplast DNA markers and double-digest restriction site-associated DNA sequencing (ddRAD-seq) data were performed on Viola orientalis, one of the representative species of the group. Phylogenetic analyses using ddRAD-seq data revealed that the populations of V. orientalis were clustered into five clades, among which the continental clades made of populations from Russia and Korea diverged more than 100,000 years earlier than the Japanese clades. The Japanese clade likely diverged during the last glacial period, followed by a further postglacial divergence into the Kyushu and the Honshu subclades. Our study demonstrated that V. orientalis originated in the continental area of northeastern Asia and, during the last glacial period, has spread southward through the Korean Peninsula across the Japanese Islands. This finding supports the previously proposed evolutionary hypothesis regarding the origin and migration routes of the Mansen elements.

The genetic diversity and structure of Pulsatilla cernua, a continental‐grassland relict, were investigated using variations in chloroplast DNA (cpDNA) and microsatellites of nuclear DNA. In the analyses of three cpDNA regions, 17 haplotypes were found in 24 populations of P. cernua from Japan, Korea, and Russia. Although the route and time of migration between the continent of Asia and Japan could not be well resolved, the cpDNA haplotype network suggests the existence of several ancient lineages in Japan and a recent secondary migration from Japan to the continent. Microsatellite analyses did not indicate genetic structure among the Japanese populations, indicating the existence of gene flow across the distribution area until recently. These results indicate that the present fragmentation of P. cernua in Japan may reflect a rapid, recent reduction from a previously large, continuous distribution.

Full-grown larvae of Asteralobia doellingeriae and Asteralobia asteris wereredescribed. An unidentified gall midge forming drop-shaped flower galls on Aster scaber in Japan was identified as A. doellingeriae, which had been known only from the Russian Far East but was newly recorded from Japan. Gall midges causing flower galls on Aster ageratoides subsp. ovatus and Aster glehni var. hondoensis in Japan were identified as Asteralobia species.