Pour simmering water over dried fronds and leave to infuse for about ten minutes, covered. Strain before drinking warm, particularly in the evening to soothe the throat. One teaspoon of dried plant per cup, two to three cups per day.
Prepare a concentrated decoction of the fronds, then incorporate equal parts sugar or honey to obtain a thick syrup. Keeps for a few weeks when refrigerated, to be taken by the spoonful. Dosage should be validated with a healthcare professional or recognized pharmacopoeia before use.
It can be found in the wild in shaded and humid crevices of old walls and limestone rocks in the south of France, as well as in herbalist shops as dried plant material.
Fronds are traditionally harvested in spring and summer, before spore formation, in dry weather.