If the root system between patches is severed, the patches form physiologically separate entities but are generally still considered part of the same clone given that they are composed of genetically identical patches and parts, having been produced vegetatively.
The boundaries of different clones stand out most clearly in the early spring when flowering and leafing-out occur (in that order). Aspen occur as males and females separately, unlike the majority of tree species, which support both male and female reproductive parts on each individual." And on it goes. If you have a patch of aspen near you, do you notice the branching habits of each tree are similar and that the trees flower, leaf out and change colour at the same time, the same rate."