Ask Mr. Smarty Plants

"Designer" trees are always a tough call for Mr. Smarty Plants. We can fulfill some but not all requirements most of the time, seldom finding the perfect tree. Any tree, even an evergreen, is going to have litter. For instance, the needles of Pinus edulis (twoneedle pinyon) will still drop needles and cones, trees deemed "live" oaks generally drop all their leaves in March but promptly put on new little leaflets. Plants must all bloom in order to set seed, and both the blooms and the seeds, whether they be nuts, or tiny grains, will still fall to the ground. The size can also be a problem; you can purchase a lovely evergreen that is about 6 ft. tall at the nursery, put it in the ground and then discover that it will mature to 100 ft, or more. We are going to look in our Native Plant Database for both shrubs that might stay more in your size range, but can be trimmed up into tree form, and trees that ordinarily stay fairly small. Because Maricopa County is in USDA Hardiness Zones 9a to 9b, with apparently higher elevations and lower temperature zones to the north and east of you, we are going to choose not just plants native to Arizona, but plants native to your area of Arizona and evergreen. A plant native to northeastern Arizona would fry in your situation in southwestern Arizona. Follow each plant link to get more information about that plant. You may find that you will have to sacrifice the evergreen qualifier or the size restrictions to get a suitable tree. 

From our Native Plant Database: 

Cercocarpus montanus (alderleaf mountain mahogany) - semi-evergreen, 8 to 20 ft., shrub or small tree, low water use

Pinus edulis (twoneedle pinyon) - 10 to 30 ft,, edible seeds. More information - USDA Forest Service Mexican Pinyon

Quercus turbinella (Sonoran scrub oak) - 6 to 12 ft. More information and photos

As you can see, the options are not very numerous. We are going to suggest you contact the Arizona Cooperative Extension Office for Maricopa County, Urban Horticulture,  to give you closer to home help. Our personal choice out of these is Pinus edulis (twoneedle pinyon), but you may be at too low an elevation for it because this USDA Plant Profile does not show it growing in Maricopa County and it shows in our database as requiring "Part Shade." 

From our Native Plant Image Gallery:

Cercocarpus montanus

Cercocarpus montanus

Pinus edulis

Pinus edulis