rose moss, (Rhodobryum roseum; formerly Bryum roseum), moss of the subclass Bryidae, found throughout most of the world in woods or sheltered grassy places. Rose moss seldom forms sporophytes and capsules (spore cases); it reproduces primarily by stolons (horizontal stems that root at the nodes). Each vertical caulid (stem) is topped by a rosette of dark green phyllids (leaves) that is usually about 2 cm (about 0.8 inch) in diameter.