The Ghaf tree is a remarkable drought tolerant species native to Arabia and further to the east, tolerant of salinity and high alkalinity up to pH 9.6 and rainfall as low as 150mm per annum. The tree has a tap root which can reach 30+ metres and has some frost tolerance.
http://www.winrock.org/fnrm/factnet/factpub/FACTSH/P_cineraria.html
