Уснея: лишайник-борода, свойства и опасность.

Genus of lichens

Usnea is a genus of mostly pale grayish green fruticose lichens that grow like leafless mini shrubs or tassels anchored on bark or twigs. The genus is in the family Parmeliaceae. It grows all over the world. Members of the genus are commonly called old man's beard, beard lichen, or beard moss. Usnea looks very similar to the plant Spanish moss, so much so that the latter's Latin name is derived from it (Tillandsia usneoides, the 'Usnea like Tillandsia').

Usnea lichens are widely distributed in both the northern and southern hemisphere, in both temperate and tropical regions. They appear in areas with low levels of air pollution. They can often be found on the ground in areas with where trees or branches have recently been cut, such as orchards (after pruning) and active logging areas.

Usnea lichens reproduce via vegetative means through fragmentation, asexual means through soredia, or sexual means through ascogonium and spermatogonium. The growth rate of lichens in nature is slow, but can be increased in laboratory conditions. Like other lichens, Usnea often grows on sick or dying trees due to the pre existing loss of canopy leaves, allowing for greater photosynthesis by the lichen's algae; this leads some gardeners to mistakenly blame the lichen for the tree's leaf loss and illness. Usnea is very sensitive to air pollution, especially sulfur dioxide. Under poor growing conditions, such as areas high in pollution, they may grow no larger than a few millimetres, if they survive at all. Where the air is unpolluted, they can grow to 10–20 cm long. It can sometimes be used as a bioindicator, because it tends to only grow in those regions where the air is clean, and of high quality.

According to Paul Bergner, Author of Medical Herbalism, "the usnic acid in Usnea is effective against gram positive bacteria such as Streptococcus and Staphylococcus, making Usnea a valuable addition to herbal formulas for sore throats and skin infections. It is also effective against a bacterium that commonly causes pneumonia." Bolivian traditional healers called the Kallawaya use Kaka sunka in decoction to cure lung problems. The lichen is macerated in alcohol and rubbed onto the body of those suffering from "nervous fragility". The National Toxicology Program evaluated the issue, undertaking research involved feeding male and female rats and mice ground Usnea lichens containing usnic acid for three months at various concentrations. Rats suffered severe toxicity, with significant liver damage observed at various concentrations, while mice experienced liver toxicity, ovarian atrophy, and changes in reproductive cycles at higher doses. Additionally, both species showed weight loss at elevated exposure levels, and mice exhibited potential genetic damage after two weeks at high concentrations. A safe exposure level was established at 60 parts per million, below which no adverse effects were observed.

Usnea species have been used to create yellow, orange, green, blue, and purple dyes for textiles. This wide variety of possible colors can be achieved due to variations in chemical composition depending on the species, locality, and race of a particular specimen. Specifically, Usnea can contain thamnolic, squamatic, barbatic, salazinic, and alectorialic acids, all of which can affect dye color.

When dry, Usnea lichens are flammable and can be used as a fire starter.

Some Usnea species have been used as food sources during times of scarcity. For example, people in Bosnia and Herzegovina ate Usnea barbata during the Bosnian War, particularly in the winter, when other plant material was not readily available. They ground it into powdery "flour" to make bread or ate it as mush.

The northern parula, a species of New World warbler which breeds in North America, uses Usnea lichens in the construction of its nest in some parts of its range. Where these lichens have declined due to air pollution, the bird has also vanished as a breeding species.