@Ragman,
That's ok. Plant material was part of my business for 25 years and I can be wrong too, including about trees I thought I knew but got confused. And that was mostly in one metro area, albeit a very large and climate diverse area. Then I moved north and had to learn a whole new batch of plants. Then I moved to Albuquerque, and I say to myself, that's a nice tree, wonder what it is. Ok, I know a few of them, but I've lost my zeal for constant i.d.ing.
At least in design, you have to not only know the i.d., you have to know the trees' needs, its growth behavior, root behavior, tendency to pests, on and on. Even though I knew trees, I always read up again before specifying. Just before I left Venice, a large and powerful volunteer group was putting in street trees in a big campaign. I was the only one who refused to sign the sheet because I knew the trees picked for our street were wrong, and said so - they need at least twelve feet of planting parkway, where our street had 30 or so inches. When I go back there to visit, the trees are growing badly, including in front of my old house where the new owner must have ok'd the tree.