Iberis sempervirens (Candytuft)

 Iceland Moss is a perennial, foliaceous plant from two to four inches high; a native of Britain and the northern countries of Europe, particularly Iceland.  It is diversified in its color, being brownish or grayish-white in some parts, and of a reddish hue in others.  It is without odor, with a mucilaginous, bitter, somewhat astringent taste, and when dry the lichen is crisp, cartilaginous, and coriaceous, and is convertible into a grayish-white powder.  It swells up on water, absorbing more than its own weight of that fluid, and communicating a portion of its bitterness to it, as well as a little mucilage; when long chewed it is converted into a mucilaginous pulp, and when boiled in water the decoction becomes a firm jelly on cooling.