In North America, this Caucasian alien is largely restricted to northern regions. The only record from Ky. is the note of Gm: "seen in cultivation, or as an escape." The frequently cultivated plant known as "Russian comfrey" is a robust vigorous hybrid between officinale, which is a variable species (2n = 20 to 56), and asperum, which is more uniform (2n = 32). This hybrid is named S. X uplandicum Nym., and usually has 2n = 36 or 40. It has been confused with typical asperum in North America; see Gadella (1984) for details.