I'm trying to identify a tree, it has a dark bark, oval shaped leaves [ opposite one another on the branch ] and yellow flowers.
I'm sorry for the bad quality of the images, they were taken from my phone.




I've managed to cut two branches today :

I was hoping to make cuttings out of them, but the stems are hollow, even where the branches are coming out.
I might have taken it from a too young branch, cause the main trunk and other thicker branches are solid wood from what I can see.
Any idea what it might be anyone?