An order of the true mosses (subclass Bryidae) found in Australia and New Zealand. The order consists of a single species, Mittenia plumula, which is adapted for growth in caves or cavelike places. Branches of the persistent protonema consist of spherical cells which reflect light from a backing of chloroplasts, thus providing a glow. The stems are simple and erect, and the leaves are 2–4-ranked and oblong-lingulate and blunt or apiculate. The midrib ends above the midleaf, and the cells are short and smooth. The sporophytes are terminal, the setae elongate, and the capsules erect and oblong-cylindric. The opercula are conic-subulate. The peristome consists of 16 filiform teeth, inrolled when moist and recurved when dry, and 32 smooth, hyaline, nodulose segments attached to a short membrane. The calyptrae are mitrate and smooth.