Here are two pieces of convoluted Scandy and English etymology that converge in my head.
“Marshmallow” was originally the common name of a plant, Althaea officinalis (Sw. läkemalva), from which a thickening agent was made. This agent was added to meringue foam to produce the toastable sweet pillows we all know and love. And so the sweet took over the name of the marsh-dwelling mallow plant.
On Gålö, the peninsula where I helped with excavations yesterday, is a place called Kärrmaräng. This means “Marsh Lagoon Meadow”, but the Swedish word for meringue is maräng, so “Kärrmaräng” looks like it should be read “Marsh Meringue”.
I wonder if Althaea officinalis grows at Kärrmaräng. It sounds like good place to light a camp fire and toast marshmallows.