A nirinso (Anemone flaccida) leaf, left, is pictured next to a monkshood leaf, right, in Sapporo’s Kita Ward, April 7, 2026. The shapes of the leaf tips differ, but depending on the variety, they can be even more difficult to distinguish. (Mainichi/Sahomi Nishimoto)
The Medicinal Plant Garden of the Hokkaido Institute of Public Health, which cultivates 600 to 700 types of plants, including medicinal herbs, edible wild plants and poisonous plants, is seen in Sapporo’s Kita Ward, April 7, 2026. (Mainichi/Sahomi Nishimoto)
SAPPORO — As the wild vegetable foraging season arrives across Japan, there has been a string of food poisoning cases from toxic plants.
In Japan’s northernmost prefecture of Hokkaido, an elderly man in his 80s died April 1 after eating monkshood, which he mistook for Anemone flaccida, or “nirinso” in Japanese. In late March, a man in Aomori Prefecture who ate the same plant was also left in critical condition.
In the past decade in Japan, 17 people died from eating toxic plants, and one expert has warned that “even veteran foragers must not let their guard down.” So what should people look out for?
Poisonous plants served as seasoned greens
According to the Muroran Public Health Center in Hokkaido, at around 7 p.m. on April 1, a couple in their 80s living in the center’s jurisdiction ate plants they had collected in the mountains and taken home and cooked as seasoned greens. About an hour later, they developed symptoms including body pain, vomiting and numbness in their hands and feet. The husband was rushed to the hospital at around 11 p.m. but died. The wife has since recovered.
Hokkaido Prefectural Police contacted the Muroran Public Health Center, which conducted a survey and found the toxic component aconitine, which is contained in monkshood, in the seasoned greens and other dishes. The couple thought they had picked “nirinso.”
On March 25, just a week before this incident, a man in his 50s in the Higashitsugaru district of Aomori Prefecture was taken to the hospital in a similar case and remained unconscious in critical condition with an irregular pulse and respiratory failure.
According to the Aomori Prefectural Government, the man said that he had eaten “nirinso” at home. A check of what appeared to be wild plants at the residence found that most of them were monkshood.
Toxic enough to take down brown bears
Masayuki Takahashi, chief at the Medicinal Plant Garden of the Hokkaido Institute of Public Health, provides an explanation on monkshood and nirinso (Anemone flaccida) in Sapporo’s Kita Ward on April 7, 2026. He says that since monkshood can grow right next to nirinso, it is safest to only pick nirinso with white flowers. (Mainichi/Sahomi Nishimoto)
A potted monkshood plant, left, is seen alongside a nirinso plant with white flowers, in Sapporo’s Kita Ward on April 7, 2026. Especially when shoots are just emerging, monkshood is said to be extremely difficult to distinguish. (Mainichi/Sahomi Nishimoto)
According to the websites of the Ministry of Health, Labor and Welfare and the Hokkaido Prefectural Government, monkshood grows in shaded mountain woods. Its stem reaches about 1 meter in height, and toxic compounds are contained throughout the plant. Because its leaves are deeply cut like the palm of a hand, it is easily mistaken for the edible plant nirinso.
Historically, the Ainu people used monkshood as arrowhead poison for crossbow-type traps called amapppo, with which they targeted brown bears, and as poison on harpoons used to hunt whales.
Monkshood is said to be so toxic that it can kill large wild beasts. So how can people tell the difference?
This reporter visited the Medicinal Plant Garden of the Hokkaido Institute of Public Health in Kita Ward, Sapporo, to find out. Monkshood’s Japanese name “torikabuto” is said to have come from the caps of the same name worn in gagaku (ancient court music). Masayuki Takahashi, 45, chief researcher in the pharmaceutical safety group of the institute’s department of living science, pointed out that Anemone flaccida blooms with white flowers in early spring, while monkshood blooms with purple flowers from August to October.
“The months of April and May are a time when more people go foraging, but monkshood hasn’t bloomed at that stage, making it hard to distinguish from Anemone flaccida,” Takahashi explained.
When I cautiously plucked leaves from each plant for comparison, the difference was almost impossible for an amateur to see.
Nirinso leaves have rounded tips, while monkshood leaves appear slightly pointed. But Takahashi warned, “There are around 40 species of monkshood in Japan alone, and some also have rounded leaf tips, so it’s dangerous to try to identify them by the leaves alone.”
The safest method is to pick only Anemone flaccida plants that are in bloom with white flowers. However, Anemone flaccida and monkshood can sometimes grow together, so Takahashi says people need to be careful not to assume that a flowerless plant next to one with white flowers is also Anemone flaccida.
Deadly poison found even in garden varieties
According to data compiled by the health ministry, there were 218 cases of food poisoning from toxic plants over the 10 years from 2016 to 2025, with 688 patients and 17 deaths.
Poisonous autumn crocus and “gyoja ninniku” (Allium ochotense or Allium victorialis) are seen planted together in a single pot in Sapporo’s Kita Ward, April 7, 2026. It is difficult to tell between the two from the leaves alone.
Autumn crocus and gyoja ninniku plants are seen growing in the same pot, in Sapporo’s Kita Ward on April 7, 2026. Gyoja ninniku has a distinct reddish-purple stem at the base, but tearing a leaf and smelling it is a more certain method of identification. (Mainichi/Sahomi Nishimoto)
Of the deaths, 13 were caused by autumn crocus, known in Japanese as “inusafuran.” Autumn crocus blooms in autumn, when flowers are scarce, and is popular as an ornamental plant because it is easy for beginners to grow.
Takahashi says that in Hokkaido, there are many cases where people mistake autumn crocus for a plant known in Japanese as “gyoja ninniku” (Allium ochotense or Allium victorialis), which is also referred to as “Ainu negi” in Hokkaido. Prefectural government statistics show that of the 13 deaths over the past 30 years, 10 were due to autumn crocus.
Autumn crocus plants don’t usually grow wild in mountain forests, but there have been cases where they have grown together with gyoja ninniku in home gardens, or where people have eaten it by mistake without realizing it had been planted by a previous resident.
The key to distinguishing between the plants is the smell. Gyoja ninniku gives off a strong garlic odor when the leaf is torn, while autumn crocus has a green, grassy smell. But care is needed in Hokkaido. People there often eat gyoja ninniku marinated in soy sauce or with strong-flavored grilled mutton, so after cooking it, they could end up eating autumn crocus without realizing it.
A few leaves can be fatal
So just how much does a person need to consume for the dose to be fatal?
“With monkshood, it depends on the variety, but just a few leaves can prove fatal,” Takahashi said. “The same goes for autumn crocus — even one piece of the bulb can be enough to kill,” he added. Cooking or heating does not break down the toxins, either.
In some cases, elderly people with preexisting illnesses may die even if they have consumed less than the normal lethal dose, Takahashi cautions.
“Even for veterans who have picked wild plants for years, a single mistake can put their lives at risk,” he warns. “Finding a patch of wild plants may be exciting, but please don’t pick anything that looks even slightly suspicious. It’s also important, as a matter of etiquette, not to be greedy and overharvest.”
People should also confirm before cooking that wild plants received from others do not contain toxic species.
Takahashi advises, “Be careful when buying from flea market apps like Mercari or direct sales outlets, as these do not go through markets monitored by public health centers.”
(Japanese original by Sahomi Nishimoto, Hokkaido News Department)