First confirmed records of Artemisia princeps (Asteraceae) in Canada: genomic and morphological evidence of naturalization

Data: trnL-F and ITS sequence alignments (fasta files), and results of the phylogenetic analyses (iqtree results and tree files). Methods: DNA sequence data from the plastid tRNA-Leu (trnL) gene and trnL-trnF intergenic spacer (trnL-F) and the nuclear ribosomal internal transcribed spacer (ITS) region were analyzed to verify species identifications based on morphology. Total DNA was extracted and PCR-amplified following the protocols outlined in Verloove et al. (2020). Forward and reverse sequences were assembled using Geneious Prime v2023.2.1 (Biomatters, Auckland, New Zealand). The resulting sequences have been submitted to EMBL/GenBank under study number PRJEB91553. Alignments for trnL-F and ITS were performed using MUSCLE (Edgar 2004). Phylogenetic relationships were inferred using maximum likelihood with 1000 ultrafast bootstrap replicates and 100 standard bootstrap replicates in IQ-TREE v2.2.2.7 run via the IQ-TREE web server (http://iqtree.cibiv.univie.ac.at). Abstract: In this study, we report the first discovery of the Southeast Asian species Artemisia princeps, a member of the A. vulgaris complex, along the banks of the Fraser River in Greater Vancouver, British Columbia, Canada, in 2011. Its identity was initially determined based on morphological features and later confirmed through molecular analyses. The species has since proven to have established extensive populations in the region. Herbarium revisions indicate that A. princeps was previously collected in the area in 1956 and 1989, though it was misidentified as A. vulgaris, a widespread Eurasian species. It is likely that A. princeps was intentionally introduced for medicinal purposes by Japanese immigrants over a century ago, after which it spread widely. Despite the known invasiveness of several species in the A. vulgaris complex, their ecological impacts remain understudied. In Greater Vancouver, A. vulgaris is the rarer of the two species, a pattern that may extend across North America. Consequently, American populations identified as A. vulgaris should be re-examined, also considering the potential presence of another closely related species, A. verlotiorum. This paper discusses the morphological distinctions between A. princeps, A. vulgaris, and A. verlotiorum, while also tracing the naturalization history of A. princeps in southwestern Canada.