Symphytum Uplandicum and Symphytum x uplandicum are the same plant as far as I can find.

A quote:
"Russian comfrey, Symphytum uplandicum Nym. (formerly Symphytum peregrinum), is the result of a cross between Symphytum officinale and Symphytum asperum (prickly comfrey) and is a tall herb growing up to two meters in height."
from http://www.hort.purdue.edu/newcrop/med-aro/factsheets/COMFREY.html

And another using the synonym:
"Perennial, shrubby herb, with powerful mucilaginous roots that go down to a depth of 2Â2.5 m; basal leaves lush, forming a rosette the first year, 30Â100 cm long; stem-leaves hairy, petioled, broad pointed, often up to 5 cm in length, rough-textured, on succulent, grooved stems; inflorescence tall, terminal cyme, up to 1.3 m tall (to 3 m tall on good rich soils); flowers magenta-pink, or blue, bell-shaped; plant usually does not set seed."

from http://www.hort.purdue.edu/newcrop/duke_energy/Symphytum_peregrinum.html

The chromosome number is 2n=36 and is even, so there is a possibility that it might set some viable seed at a low frequency.