Horehound - Marrumbium vulgare - see http://en.wikipedia.org/wiki/Marrubium_vulgare.

I don't think the Traditional English Dandelion & Burdock that quenched many a childhood thirst had much to do with either of its eponymous components. I might still buy a can today actually, chilled, from the corner shop with a quarter of peanut brittle (or whatever metric measure come close). I've a yen for such things; McDonald's was never the same when they stopped serving Root Beer - nothing quite like a Big Mac & Fries washed down with a large slop of what tasted for all the world like liquid Germolene.

I was once told that Dandelion & Burdock was just thing for marinading freshly killed hare. One thing I did used to do was to douse a red hot poker in it, after watching my grandmother doing likewise with her Mackeson's. Nice on a winter's afternoon...