SCREW MOSS

also called Twisted Moss, any member of the moss genus Tortula (order Bryales), which form yellow-green or reddish-brown cushions on walls, soil, rocks, trees, and sand dunes in the Northern Hemisphere. About 25 species are native to North America; the best known species in both North America and Great Britain are T. muralis and T. ruralis. Screw moss ranges in height from 0.5 to 10 centimetres (about 1/5 to 4 inches), depending on the species. The tongue-shaped phyllids (leaves) are usually tipped by a long hair. The teeth surrounding the mouth of the capsule (spore case) are often spirally twisted and are united at the base into a tubular membrane.