Polytrichum commune, known as common hair cap moss, grows 1 to 8 inches in height. The moss appears across the ground like a soft green blanket or carpet. The moss normally lives three to five years but has been known to reach 10 years before dying. As the moss dies, new moss develops on top of the old.
Polytrichum grows wild around the world and is a coveted garden addition that is often grown around stepping stones. The plant enjoys moist soil conditions with deep shade. It will tolerate full sunlight but its water requirements increase and the soil must be maintained moist for the plant to survive. It will tolerate areas with poor drainage. Polytrichum does not require nutrient-rich soil and can subsist on less then adequate soils. It does prefer acidic soil conditions.
The moss offers numerous benefits for soil erosion control. It is also commonly found growing on and along granite outcroppings with virtually no soil available. Polytrichum grows along roadsides and in forest settings with ease. It offers moderate pollution tolerance for growing in or beside urban areas, according to Ohio University.
Polytrichum has both male and female stems. On the tips of female shoots, eggs are produced; on the tips of male shoots, sperm is produced. The ends of these structures appear almost cap-like. Male caps often have a pretty pink shading. The shoots range in height from 11 to 15 inches. The plant requires springtime rain to procreate. Raindrops splash sperm from the male shoots onto the eggs so fertilization can occur.
Once the egg is fertilized, it begins to transform into a fertile spore. When warm, dry summer weather comes, the wind lifts the spores off the shoots and sends them on their journey to land in soil somewhere else and germinate.
Polytrichum is often brewed into a tea and drunk to dissolve gallbladder or kidney stones. The shoots of the plant were once utilized in hair-care products to aid in hair growth and make the tresses stronger. The shoots were once woven into baskets and rugs. A polytrichum basket from 86 AD was discovered at an early Roman fort in Newstead, England, according to the Faculty of Natural Resources Management at Lakehead University.