The Norway maple came to North America in the 18th century, imported by a Philadelphia merchant and peddled as a garden adornment. But lately it has been turning up in all kinds of places, including the official logos of Wilfrid Laurier University in Waterloo, Ont., and the FIFA under-20 World Cup of Soccer.
The Canadian Television Fund and the Alliance of Natural History Museums of Canada have also made maple leaf errors, according to botanists.
Sean Blaney, senior botanist of the Atlantic Canada Conservation Data Centre, said he never expected to see the Norway maple leaf on a $20 bill.
"It's a species that's invasive in Eastern Canada and is displacing some of our native species, and it's probably not an appropriate species to be putting on our native currency," Blaney told CBC News.
A 'stylized blend' of Canadian maple species
The Bank of Canada, which makes the banknotes, denied the bills include a Norway maple leaf. A spokesperson said the leaf is a stylized blend of different Canadian maple species.
But Blaney argued it looks nothing like any of the 10 maples native to Canada.
"It seems a bit like an after-the-fact explanation to me. The bottom line is that, the image on the bill looks exactly like a Norway maple, however it was derived," he said.
University of Ottawa Prof. Julian Starr, also a research scientist at the Canadian Museum of Nature, specializes in plant identification and classification.
He has been consulted by the Royal Canadian Mint about the botanical accuracy of its coins, but he was not shown this maple leaf.
"This could not be confused with a native species of Canada," said Starr. "It basically looks like a Norway maple."
There are 400 million bank notes already in circulation, including $20, $50 and $100 bills. There are plans to print another 1.2 billion more bank notes, including $5 and $10 bills.