During summer the plants produce purple and black fruit that are a similar size to blueberries. They taste sweet, but, along with most other parts of the plant, contain the poison tutin.
A specific antidote for the toxin doesn't exist.
Dr Paul Gee, Canterbury DHB emergency medicine specialist, said suspected and/or confirmed cases of tutu poisoning are reported every year.
Although almost all patients recover, deaths have been reported in the past.
Tourists have had unexplained seizures and collapses after eating the berries.
Livestock - and allegedly circus elephants - have also died after eating tutu.
Tutu berries
• Tutu berries are purple or black berries, about the same size as blueberries.
• They are sweet but highly toxic.
• If you or someone else eats them contact the National Poisons Centre on 0800 POISON (0800 764 766).
• Medical treatment is almost always required.