About 4 years ago, 2 "fern like" shrubs started growing in my rather small garden. Since then, those shrubs have grown into trees that are 14 feet tall. New branches are all green with very soft wood that dies back to the old wood in winter. I pruned and bound them to look like trees. I have seen no type of flower clusters, but the leaves are identical to sumac. It smells citrusy/spicy when leaves are bruised. I like the trees, but as it is close to my house, would like to know what it is and how to curtail excessive root growth.