Quercus viminea

Willow-leaf oak is closely related to emory oak, but the leaves are generally much shinier, slimmer, longer and brighter green. Branch tips are generally less robust than emory oak. There is overlap in range of the two species in northern Sonora, but generally as one heads south Q. emoryi fades out as Q. viminea becomes more common. in areas of overlap they grow at different elevations with the emory oak at the lower end of the oak zone, often with blue oak. Quercus viminea usually grows in the mid to upper oak woodland zone and into the pine/oak  zone.

The only record in Arizona is in the Patagonia Mountains from the 1920's. The Sierra Pinito literally has forests of these tree and it is surprising that they do not occur in Arizona Sky Islands.