brusttea or breast tea = ברוסטטײ was one regional common name in the Pale for marshmallow
Marshmallow or Althaea officinalis has long been known as a healing herb, helpful in so many hot, dry conditions. One source we consulted for our book told of Ashkenazi children who were were regaled with a pun when they had a cold and needed marshmallow tea. In that part of the Pale of Settlement, marshmallow tea was called “eibischtee” which was very close to “Eiberste” or the "Supreme One" so children who were a little sick were told that Eibeschtee (which sounds very close to Eiberste) would help them.
From the regional Yiddish name, breast tea, and the regional Yiddish pun for this gentle plant’s healing abilities and many other scattered clues we can reimagine how marshmallow was understood to be a soothing, cooling and moisturizing remedy called on for chest complaints or hot dry coughs brought on by colds and fever. I like to add a little of the dried root to tea blends that tend to be drying, especially those with nettles.