I can walk through procedurally generated trees, but I don't want to...?

I’m using the procedurally generate feature and I’ve set many foliage types to be generated and it all generates fine, but when I play through I can just walk straight through all the trees. (I understand that usually foliage can be walked through in games, but is there a way to make it so I can’t, because all my foliage are trees.)

do your trees have collision?