SC - Russian Birch Beer?

[Jeff Gedney]

Ahoy the list,
While reading Hakluyts "Voyages" (published in very late Period - about 1590 
or thereabouts), I came across a reference in the section covering the 
Muscovy Company, from about 1530, or so, when a corresponcent was 
describing the foods and drinks of the Russians with which he was 
presented while essentially trying to hammer out a trade deal in Moscow.
He described several types of "meades" ( including a good working
description of kvass ), one of which was " mayde of the root of the Birche
tree" ( I forget now what it was called. It was named, but the book went
back to the library ).
Do any of you know what this was, and how it was prepared? 
any have a copy of the Domestroi? is it in there?

Brandu