It is just over our wall in an empty lot. Now the "empty lot" is nothing more or less than raw desert, not counting a bit of detritus that has washed in over the years. As far as plants go, it features mostly Larrea tridentata, the creosote bush; but there are a few other plants scattered around, among them this one. The tree is more like several trees: a small thicket of Parkinsonia floridum, the blue Palo Verde. I've posted pictures of it before here because it is beautiful to photograph. As I say, it grows up against the wall surrounding our property.
One of the most beautiful things about Palo Verde trees is the bark, which is smooth and green. The colour is important since it allows the tree to conduct photosynthesis even when leafless. This is a not uncommon feature of desert plants, many of which deal with drought and heat by dropping their leaves in summer, thereby reducing water loss from the leaf surfaces. Some Parkinsonia species have brilliant green bark, but P. floridum's is a soft grey-blue-green hue.
And, like so many other desert plants, it is protected by thorns.
I hesitated to post this tree, feeling that it would probably not change enough from month to month to remain interesting. But this meme is a good opportunity to find out the little variations that one didn't know about. So here is Parkinsonia floridum in March...