Yes, Susan's paper acknowledges that the modern definition of a gruit is an herbal un-hopped beer (page 3):
As I am not trying to make a historic recreation of a German or Dutch gruit from the 1500s, but rather trying to make a modern beer without the use of hops. Therefor I am comfortable...
Unfortunately, the first 2 places I looked didn't have any myrica gale. There is 1 other local park with a bog walkway for me to check.
We have tons of ground ivy growing in our yard & garden. Not sure the flavor is something I want to have 5 gallons of (I only keg, don't have the bottling...
I don't know if you have seen this paper specifically regarding beer spoilage organisms, but it appears Myrica Gale/Sweet Gale/Bog Myrtle has enough anti-microbial powers to keep lacto in check, at .8 oz/gal or 6g/l of dried leaves. Half of that wasn't enough however. While sanitizing is...