Buttress roots are large roots on all sies of a tall or shallowly rooted tree. Typically they are found in rainforests where soils are poor so roots don't go deep. They prevent the tree from falling over (hence the name buttress) and help gather more nutrients. They are there to anchor the tree and soak minerals and nutrients from the ground, a function that would prove difficult if the tree was unsoundly rooted. The roots interwind with other buttress roots from other trees and create an intricate mesh, which helps to support all of the other trees surrounding it. They can grow up to 15 feet tall and spread for 30 or so metres above the soil then for another 30 metres below. When the roots spread horizontally they cover a wider area to collect nutrients. They stay near to the top because this is where all the main nutrients are. The roots are close to the surface and can be seen to have spread over a large area.