The Postniki (постники "fasters") were a millennial sect of 19th century Southern Russia, a branch of the Khlysty (flagellants) movement, founded by Abbakum (or Avvakum) Ivanov Kopylov (Аббакум / Аввакум Копылов, 1756–1838), a peasant of the Tambov Oblast. Kopylov declared himself the living Christ and gathered a considerable following in the 1820s. After Kopylov's death in 1838, the sect disintegrated in various schisms, giving rise to follow-up groups such as the Staroizrail (Old Israel) sect led by Kopylov's disciple Perfil Katasonov.
Soviet scholar A.I. Klibanov still encountered several postniki in Rasskazovo in 1959.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction