OTTAWA (AFP) - The maple leaf shown on Canada's new $20 bills is from a Norway maple, which is not native to Canada, several botanists cited by Canadian media decried on Friday.

Canada's iconic red maple leaf image appears on its flag, government logos and countless other branding of Canadiana.

"It's our national symbol - it's stunning that we continuously get it wrong," University of Ottawa professor Julian Starr told broadcaster CTV.

The Norway maple leaf, Mr Starr and others pointed out, has five main lobes and the tips are stringy while Canada's sugar maple leaf has just three lobes and the tips are not stringy.

Norway maple trees were introduced to North America in the 1800s but are considered invasive and have been banned in at least two United States states. Canada has 10 native maple species.

The Bank of Canada dismissed criticisms, saying the leaf is not Norwegian but rather a "stylised Canadian maple leaf" and does not represent any specific species of tree.

The polymer banknote first went into circulation in November.