I just had a ~60 yr old, ~50' Modesto Ash removed from our suburban backyard - it was wonderful (lovely canopy, strong trunk and branches, attractive, non-invasive root system, no random seedlings, etc.), but some landscaping errors and age contributed to its ultimate demise.

The roots were ground out and I now have a 5' x 5' bed (surrounded by hardscape and grass) in which to plant a new tree. Arborist is suggesting a 24" box size and says immediate planting is ok.

I've done some research, and a Chinese Pistache seems well suited to this site, however, I can't find anything specifically about the CP's root system.

I need a deep rooted system as there is significant hardscape and other landscaping nearby. (I have 3 beautiful locust trees, and while I love them, they make me CRAZY with their shallow, invasive roots and dozens/hundreds of suckers that shoot up constantly).

Slow growth is ok, we are patient. An eventual shade canopy is a must. No seeds/berries (I found a GardenWeb discussion that said to get a male tree only, or a "Keith Davies" cultivar).

Am I on the right track or do you have other suggestions? A jacaranda is also in the running - any pros/cons to that, particularly in the invasive-root area? Can anyone comment on their experience with the roots of either tree?

Thank you!