Montreal's flag and coat or arms were adopted all the way back in 1833. The symbols which adorn the flag were chosen to represent the nations who founded Montreal.
The red cross represents the Christian motives and principles which governed the founders of the city.
The blue fleur-de-lys, represents the French, the original settlers of the city. (originally a beaver)
The red rose represents the English.
The shamrock, represents the Irish.
And the thistle, represents the Scots.
But now the city of Montreal has updated the flag and coat of arms to better represent the city's origins.
The new flag now includes a White pine in the center of the cross, which stands for the original native presence in Montreal.