I went to go visit "Calgary's largest tree", the one near the curling club in crescent heights park. It is very impressive but not calgary's largest. The one in that backyard (near memorial drive) is still larger.
Here is a pic of the one in Crescent Heights Park. The form of the tree is outstanding and looks more like an oak.
The tree along memorial drive (in the backyard) is just so much larger and it is really difficult to get a sense of the scale in pictures so I dont have an image of it.