Can you direct me to where I can buy a 50 caliper yellow wood in Toronto?
The scientific name for the yellowwood tree is Cladrastis kentuckea. The following link gives you a few details about this tree.
In terms of where to purchase this tree, Master Gardeners do not endorse specific businesses. Try your local large nurseries. Ask if they have the tree or if they can order it for you. If you have no luck there, you could try Landscape Ontario’s “Find a company” service http://landscapeontario.com/find-a-company
Thank you for contacting Toronto Master Gardeners.