Yet another mystery tree spotted by my compatriot around San Jose, CA. It sure does look like an Empress Tree, but I'm not convinced to the utmost. Or is it? P. elongata? P. fortunei? P. kawakamii? (These are the species I haven't seen yet.)
Paulownia. Species identification based on infl. structure and structure of hairs on leaves. Online FLORA OF CHINA has covered this genus by now, I believe. Otherwise an older treatment with diagrams and keys used to be up, perhaps still is. The overwhelming majority of specimens encountered up here turn out to be P. tomentosa when checked, even when they look "different" at first.
Here's the link to the Flora of China: http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=124177
