Photo: Diane Edwardson, June 12, 2012. For the past 2 years, we've tried to identify this tree. It's not Southern California Black Walnut; this tree has much larger leaves and fruit. (Click on photos to enlarge.)
The squirrels always go nuts for this fruit. It's 3 times the size of the native Southern California Black Walnut.
A reader from Northern California suggested it might be California Buckeye. Since the squirrels always stripped all the fruit before it matured, I had to wait until it flowered. I missed the flowering last year.
Photo: Diane Edwardson, April 7, 2012. This year's flowering proved it was not California Buckeye, but a walnut species. I'm speculating it's Juglans nigra, or Eastern Black Walnut.
See our post from July 10, 2010 for a cross section of the fruit.
The fruit matches the Juglans nigra fruit seen on the Missouri State University website.