Your link story mentions birches throughout (and has a photo of birch containers), but birch sap is good for drinking too; My godmother collects it every year from her trees, and she is vigorous and healthy as ever, closing on her 80th bday... the first link of mine mentions the most common use of birch, in Finland that is, too; "the 'switch'", ie. bunch of birch twigs tied together, "of European white birch to stimulate circulation during a sauna bath." And a modern Finnish invention is Xylitol, sugar made from birch sap, which finally has got permission for use in the US too.

BIRCH

Celebrating Birch: The Lore, Art, and Craft of an Ancient Tree