Is Maxifort a S habrochaites cross? Asking because one of my Maxifort rootstocks grew out and I didn’t prune it for months. It was identical to my habro x domestic F1’s. Crazy vigor, little round leaves at the stem-leaf junction, big flowers, GWR fruits with dark green lines on bottom, funny habrochaites smell, just perfectly identical.

Googling didn’t yield any answers, just lots of expensive seeds for sale.