I had a similar problem, once upon a time, with sassafras. I quickly learned to identify the trees by their variety of leaf shapes :)

I have a perverse attachment to urban mulberries. They're often unattractive, especially when abused, litter sidewalks (and make me leave stains on people's expensive carpeting) and attract birds that further clog the sidewalks with droppings. I love them anyway -- it's nice to see a seemingly invincible plant that can feed birds, squirrels, and humans, and grow nearly everywhere. My husband, a former Wicca practitioner, tells me they're also associated with prosperity... based on their talent for showing up where least expected, I'd associate them with the trickle-down theory :)

Nice photos too.