Ventnor Botanic Garden was unsure where the plants, thought to be death caps, were growing. The 40-year-old woman died last week and a 20-year-old relative is in hospital. "We don't know the exact location of the mushrooms," said a representative for Isle of Wight Council, which runs the garden.
"But mushrooms do not form part of the exhibits here, and were probably growing naturally somewhere in the vicinity of the garden."
The car park near Ventnor Botanic Garden also led to coastal pathways, fields and meadows, he said.
The garden's curator, Simon Goodenough, was on annual leave and unavailable for comment.