How do black walnut trees reproduce?

The black walnut is like the other nut trees in that the nuts are the reproductive "unit" the tree grows and drops. Plant a black walnut, and (if conditions are acceptable) a new tree will sprout and grow. If the nut can roll away from the parent tree a bit, it will have more room to grow. And if an animal helps with a bit of transportation to improve dispersion, so much the better.