I used Potentilla nepalensis 'Ron McBeath' (Miss Willmott Potentilla) as a groundcover in a landscape installation. The following season most of the original plants had died, but seemed to be replaced by potentilla anserina, AKA Silverweed. The leaf became small and ferny in appearance and the bloom changed to small yellow blooms, and numerous red runners formed an invasive mat. The second year, this had invaded the lawn up to 40 feet away.

I am wondering if it is possible that the Miss Willmott variety was a hybrid that seeded, and the seeds produced a throwback to p. anserina. They are both of the Rosaceae family, and p. anserina is not common in this state.

Can anyone explain or confirm what happened here?

Thanks