Lycopodium (Lycopodium clavatum L.) is a plant that grows on several continents and belongs to the clubmoss family. It is known also as club moss, common club moss, stag's-horn clubmoss, wolf's-foot clubmoss, running clubmoss, running pine, ground pine, princess pine, creeping cedar, and others.
 
Club mosses are not true mosses,  theyare larger and taller. Club moss reproduction occurs through the dispersal of spores, found in sporangia, located singly or in groups, or in a yellow cone-like tip known as a strobilus. 
 
Club mosses are bio-accumulators of aluminium, they were historically used in folk dyeing (in the Finnish Iron Age for example) as a mordant.
Use at 100% WOF (I have seen also recipes for 200%), you can either make a mordanting solution with the clubmoss, strain and mordant your fabrics while heating, or add the clubmoss directly to the dyebath.
 
I advice to use this for special products such as historical re-enactment, for regular dyeing best stick with regular alum. Club moss is rather rare, and even protected in the Netherlands and Belgium. The only reason I offer it on the website is to be inclusive of all materials used in traditional dye processes. Our club moss comes from Romania.