We are providing the following update regarding the growth of Apiaceae plants resembling Giant Hogweed (Heracleum mantegazzianum Sommier & Levier; Japanese name: Baikaru-hanaudo) on the Sapporo Campus of Hokkaido University, as first reported (in Japanese) on June 25, 2025.
・On June 24, 2025, the plants were brought to our attention by an external source. They were located in an area easily accessible to the public and near a daycare center. Given that Giant Hogweed is considered an invasive alien species with adverse effects on ecosystems in some countries, we consulted with the Ministry of the Environment, Hokkaido Prefecture, and the City of Sapporo. On June 25, we removed the flowers and leaves and collected samples for species identification and phototoxicity testing. All above-ground parts of the plants were subsequently cut down.
・Although our university's botanists attempted to identify the plant based on its morphology, conclusive identification could not be made due to the lack of reference specimens and previous overseas cases of taxonomic confusion with similar species. For these reasons, further identification remains difficult. However, based on several distinguishing features, it is clearly different from the native species Heracleum sphondylium L. subsp. montanum (Schleich. ex Gaudin) Briq. (Japanese name: Oh-hanaudo).
・Some overseas species similar to the plants found on our campus, including Giant Hogweed, have been reported to pose health risks, and it is possible that the plant found on our campus also contained compounds that could cause dermatitis.
・A thorough survey of the entire Sapporo Campus was conducted by a professional contractor over two days, July 1 and 2, with additional confirmation from relevant university faculty members. No other instances of the target species were found outside the originally reported location.
・As seeds may remain in the soil, the area will remain off-limits. We will continue to remove the above-ground parts of the plant (if present) each year before it flowers and aim for complete eradication. Additionally, we will monitor the emergence of the plant in other locations in our annual ecological survey.
・We are currently preparing to conduct a preliminary phototoxicity test to evaluate the chemical composition and potential health risks associated with the plant.
We will continue to work closely with the Ministry of the Environment, Hokkaido Prefecture, and the City of Sapporo to address this issue. Hokkaido University remains committed to conserving biodiversity, including the control of invasive species.
