|Long shot, but since yoru Monrovia, I bet you can nail the following:
My mother had planted what we believed was a chinese pistachio tree.
However, I don't believe it is as leaves are so different. I don't have access to the tree (planted up near Fresno CALIF). Leaves are shaped more like silver dollars / bell shape, leaves are a dull green that turn vibrant colors of orange, crimson, red during fall. Bark is light color. Tree took on nice dome and would grow to an estimate 20-35 feet.
|It's really difficult to identify a tree without seeing it. By the shape of the leaves, it doesn't sound like a Chinese pistachio. More like an oak or an aspen. You didn't mention whether it was evergreen or deciduous and whether or not it flowers or bears fruit. These points are important in terms of identification. You can submit another question with more detail, or ask someone in Fresno to take a few leaves into a nursery for identification. Best wishes with your garden!