Polytrichum juniperinum (Juniper haircap moss)
Species: P. juniperinum
Binomial name: Polytrichum juniperinum
Synonyms: Polytrichum apiculatum, Polytrichum juniperinum var. waghornei
Common name: Juniper haircap moss, Juniper polytrichum moss.
Polytrichum juniperinum is a perennial species of moss that is widely distributed, growing on every continent including Antarctica.
It has stiff green leaves that are reddish brown and more appressed to the stem when dry. The leaves have a short reddish brown awn. The leaf is rather complex for a moss. The hyaline leaf edges fold over to cover several parallel photosynthetic plates (lamellae) that are one cell thick and several cells high and run longitudinally along the leaf surface. The capsule when mature is reddish brown, sharply four angled, and constricted at the base. The calyptra is very hairy.
Although their growth form can be varied, they generally grow in thin, interwoven mats, and hardly as closely associated individuals. Juniper haircap moss have a well-developed system of tiny tubes for carrying water from the rhizoids to leaves that is uncharacteristic of mosses, resembling the system that has evolved in vascular plants such as ferns, gymnosperms and angiosperms. As a result of this developed system, stems have greater potential for height than in typical mosses.
The anatomy of the Polytrichaceae is among the most interesting of all mosses. The four angled capsule has a column at the center, like most mosses, called the columella. Unlike other mosses, the end of the columella expands into a membrane that butts up against the 64 small, blunt peristome teeth. This membrane is called the epiphragm. When the epiphragm is bumped, it sifts and ejects spores between its surface and the peristome teeth like a salt or pepper shaker.
It is a dioecious plant, meaning that the male and female gametophytes are on separate plants. Juniper haircap moss has very obvious male and female parts. Male plants are said to be unusual because they continue growing without losing the old male organs. The male plants are very noticeable due to their bright reddish orange modified leaves that form small terminal 'flowers' at the shoot ends. The plant has a gametophyte dominant life cycle similar to other mosses. Water is required for reproduction to take place, to enable the sperm to swim down the neck of the archegonia to reach the egg. Once fertilization takes place, the sporophyte of the juniper haircap moss lives on the female gametophyte, growing out of the archegonia. The sporophyte consists of a foot, stalk, a spore capsule, an operculum, and a calyptra. There are 64 short blunt teeth at the top surrounding the capsule mouth and the hood of the capsule, the calyptra, has long hairs that extends down the entire length of the capsule, hence the name 'haircap moss'.
Juniper haircap moss is very common and widespread and grows across a wide gradient of habitats but it is most commonly found on dry, acidic, exposed habitats. It is frequent in areas that previously experienced disturbances such as fire and logging. Other areas they occupy are mineral soil, humus and rocks, stumps, banks, trail sides and dry open woods. Juniper haircap moss is rarely in moist or wet woods.
On soil or humus (frequently overlying rock), sometimes on stumps, characteristic of banks or sides of trails in rather dry, open woods or pastures.