In the search for a final truth to this issue of where oil of
wintergreen comes from, I made time for consulting the "bible of
horticulture", Bailey's. I have both the earliest volumes and the
most recent. Under Gaultheria procumbens, called familiarly
Wintergreen, Checkerberry, Teaberry, Mountain Tea, Ivry-leaves, the
books cover all the ranges where it grows and the descriptions and
ends by saying "Original source of oil of wintergreen, *now obtained
from Betula lenta."
To the Birch pages I go and find Betula lenta, variously known as
Cherry B., Sweet B., Black B., Mahogany B., and Mountain Mahogany.
Following it's descriptions of range and such, it says : * "The wood
is used for various articles, and the young twigs and bark are the
main source of oil of wintergreen."
These plant names are difficult to pin down, but Baileys is the final
authority and they cross-ref. as best they can. For instance that
Black Birch - B. nigra - is also known as the red birch or Betula
All this is from Hortus Third compiled by Staff of the
L.H. Bailey Hortorium, Cornell University.
Hope this puts you all in a growing mood. Think green.