All the pictures I have of trees are on film. My wife has a digital camera but I couldn't tell you how to transfer the images. I didn't own a computer until 5 years ago. Only really use it for TB and email. I'll see what I can do about getting some pictures.
We don't have black cottonwood here but close enough. Kind of struck me while I was goofing off that there are some more westerly poplars and sure enough...
I'll find something in a min. Probably be easy and I'll make sure really is what it is...