Part of the scene setup used the create the example image is shown on the left.
The empties (represented by the green cone shapes) are all in the same group and their locations are used as starting points.
The parameter settings were as shown on the right. As usual the code is available as a zip-file on GitHub. More info on how to use the tree add-on can be found in two previous posts: A new tree add-on and A new tree add-on part II: better workflow