Since the middle ages, fern glass became part of everyday life in northern Europe. It was familiar enough to find its way into literary verse on matters of the heart. There is a nice reference to fern glass by Geoffrey Chaucer, in The Squires Tale:
But notwithstanding, some said that it wasChaucer, in turn, borrowed this reference from an epic twenty-two thousand line French poem from the late thirteenth century, when the technique of making glass from ferns was already ancient.
Wondrous to make fern-ashes into glass,
Since glass is nothing like the ash of fern;
But since long since of this thing men did learn,