Unlike a certain cola drink which touts itself as the "real thang", there is little consensus as to which moss is the "real" xmas moss, which is not surprising given that there are probably 100s if not 1,000s of aquatic mosses in existence. Individual species may also display wide growth variation. Just try out any moss(es) you like, from whichever LFS, and grow it (I personally like the "xmas moss" found at Bioplast though). If it grows well, it shouldn't matter if it's the real McCoy or not.
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