I live in Aspen Parkland (Edmonton area), would Oplopanax horridus be found here? It looks an awful lot like a plant I have been trying to identify, its quite common in the woods around my home, but my books don't suggest it should be.
Re: Maples & maple-like leaves - Part One E-Flora BC shows sightings of O. horridus extending to the north and west of Edmonton, but nothing in Edmonton. However, I would expect that it could survive there in wet areas, its usual habitat.
If it was near a major urban centre like Edmonton, it should have been documented with a collection already, but it is absent from there in the collections documented through Canadensys. My suggestion is to post a photo for ID.