If you want to eat mushrooms, don't pick wild ones - buy them.
That's Poison Information Centre director Dr Rick Lau Fei-lung's warning after the mushroom Amanita farinosa came close to killing a Hong Kong couple and made another man ill two days later.
The farinosa - named for its mealy appearance - is a member of a genus notorious worldwide for its 50 per cent mortality rate. Just one or two pieces could kill, Lau said.
Even so, it is not the most dangerous. That distinction goes to the Amanita phalloides - commonly known as the death cap, and most deadly not only among its genus but of any mushroom.
Lau said while there was no record of phalloides in Hong Kong, it was found in Shenzhen and Guangzhou - along with the related Amanita verna that regularly poisons people in the provincial capital - and its presence in the city was "very likely".
"Most other commonly seen toxic mushrooms only upset the digestive system. But Amanita are hepatotoxic in that they also damage the liver and cause failure [of the organ]," he said.
Lau said it was surprising that Amanita poisoning had never been seen before in the city, and suddenly two cases involving three people came to light in a short span of two days.
Besides the couple - Tony Wu Tung-ping and his wife Wong Ngan-lin - a 74-year-old man was also poisoned by eating wild mushrooms he picked at Tai Mo Shan Country Park.
Toxins from the Amanita genus were found in the elderly man. His liver was damaged, but he was cured by an antidote stocked in Lau's centre.
Of the approximately 400 mushroom species recorded in Hong Kong, about a dozen were toxic, Lau said.
The Macrolepiota neomastoidea, Lepiota cristata and Chlorophyllum molybdites were among the most commonly seen mushrooms with mild toxins that affected only the digestive system.
From 2009 to last year, 29 cases of mushroom poisoning were reported - including five last year - with 13 of them related to the mushrooms being picked by the victims. "All cases that came to me involved mushrooms which were not colourful, just like those that we often eat," Lau said.