Both, but especially width.
I think it should look a little bit like umbrella. Actually, baobabs have wide treetop with very dense foliage, so water from soil and root system of the tree does not evaporate as much as from surrounding savanna. It helps them to survive there. But they lose their leaves in the driest part of year, so our trees may have small young leaves and so their treetop is not as big as usually.
I am sorry for being such nitpicker and I look forward to play this level much.