Ten endangered plants were chosen for the set
The rare Bristol onion features in a new set of stamps on endangered plants unveiled by the Royal Mail.
The Avon Gorge is the only place in the United Kingdom the plant, also known as the round-headed leek, is found.
It is one of 10 plants chosen for the issue from more than 450 species of wild plants facing national extinction.
A Royal Mail spokeswoman said: "It is easy to forget that plants underpin the whole ecosystem. There is a serious threat to these wild plants in the UK."
Eddie Mole of Bristol Zoo Gardens said the Avon Gorge was famous for its rare plants.
"We are delighted the delicate beauty of the Bristol onion has been illustrated," he said.