Orthotrichum casasianum

Orthotrichum casasianum
Scientific classification
Kingdom: Plantae
Division: Bryophyta
Class: Bryopsida
Subclass: Bryidae
Order: Orthotrichales
Family: Orthotrichaceae
Genus: Orthotrichum
Species:
O. casasianum
Binomial name
Orthotrichum casasianum
F.Lara, Garilleti & Mazimpaka (1999)

Orthotrichum casasianum is a species of moss in the family Orthotrichaceae. It is endemic to the Spanish province of Álava, in the Basque Country. It grows in less than 200 trees on the banks of the Bayas river. The species is critically endangered, and was added in 2013 to the Basque Catalog of Threatened Species.