hi there, been following this forum with interest, as I am about to start my final year science degree project on comfrey, comparing the pyrrolizidine alkaloids in officinale with those in russian comfrey, expecting russian comfrey to have higher levels. Is ALL russian comfrey sterile, and cultivated by root division only, or just the BOCKING cultivars.
can russian comfrey still cross breed with officinale? if the two plants are in the same garden or field, will the officinale continue to seed true to type, and the russian comfrey not breed as it is sterile?
any answers would be much appreciated. thank you