I hope its not, but i dont have any species information on that tree, but understand its a invasive species. I think its also called mimosa. If you indeed have Mimosa you should destroy the seedlings immidiatly because it can be very difficult to eradicate once established.
The leaves to me look like they Are from the group of poplars and aspens. The seeds might be from these but im unshere. Pick a thorn. can you tear it apart with your hands (carfull not to poke urself.) Is the inside green, sticky and sweet-smelling? Poplars have flower buds that are sharp and hard like thorns.
Beans and beenpods are from the Legume Family and these definatly have thorns but their leaves are usualy compound.
The habitat would be usefull because the legums usually prefer it dry and the popolars like it wet.
The California Redbud has leaves sort of similar and seed pods but no thorns. I will reaserch. introduced species