When leaves start falling in autumn, they sometimes amaze me with their size. The enormous leaves from tulip trees, for example, can be as big as your face! This one, from a plane tree on a Berlin street, isn’t quite that large, but it’s still pretty big.
Our colleague, local ecologist, is also collecting leaves – quite a few more than I’ve gathered so far.
If you’ve found any interesting leaves in your neighborhoods, let me know!
urban plant research 
I just left a comment on the ecologist blog post you linked to, but I thought you would take interest in this too. A couple years ago I collected a bunch of yellow gingko leaves and taped them onto yellow urban surfaces in public. http://www.flickr.com/photos/spudart/sets/72157625454020854/
Hi Matt, what a great project! I really enjoyed looking through all those cheerful yellow images today. Sorry I forgot to mention this project in my post about your Christmas tree photo. Perhaps I can feature that project in a post another time.