The little greenie
In the Tucson Basin, there are two main native mesquites you will find growing in the wild--down in the washes and roadsides where water collects you will find the larger blue palo verde (Parkinsonia florida). Upon the drier, rockier soils of the foothills and banks the smaller and more rugged foothill palo verde (Parkinsonia microphylla) makes its home.
The foothill palo verde is not planted as often as the blue because it is rarer in the nursery trade, and because it is somewhat slower growing. But don't let this deter you--in our opinion, this is the best palo verde for many reasons.
Besides the fact that this species is more drought tolerant than its bluer counterpart, it also lives a lot longer and the trunk stays green (the blue palo verde will eventually develop a rough, brown bark which obscures the green trunk). And though the flowers are a somewhat lighter, more delicate shade of yellow than the other palo verde species, it is the tastier of the two.
Palo verde grows to about 10-20' tall and wide. The wide variability depends on the soil since many palo verdes are found in rocky soils, they will be somewhat stunted. Trees planted in nicer soils often found in landscapes with irrigation will grow taller, faster. Water them moderately unless you have some spots in the top zones, the driest part of your yard that you want to populate. Though palo verdes are prone to getting the grubs of the palo verde beetle (Derobrachus geminatus) they rarely succumb to any harm from them. Typically only sick trees are harmed by these amazing-looking beetles (one of the largest in our region). Even if they freak you out a little, please don't spray the grubs with that crap many garden centers will sell you--firstly, it doesn't prevent them from coming back, and for secondly, don't be an idiot and spray pesticide. You harm the good creatures along with the bad, you threaten the health of your pets and your family, so please...take a chill pill and DON'T SPRAY PESTICIDES.
Also this is an important plant for native bees and butterflies--on that subject, because it is pollinated primarily by native bees, it has sticky pollen. This means that even if you have been tested for palo verde pollen, it's not likely this is the allergen you are suffering from since it is not as airborne as many other types of pollen (look to grasses and dust as your main enemies, which during those windy springs when palo verdes are blooming, are much more likely to be the bane of your existence). Think about it, if your main pollinator is a bee, you don't want your pollen blowing in the wind, you want it sticking to your bug. So put away your allergen test results and learn some botany, and while you are at it, send your allergy specialist to me so I can school him or her on some basic botany.