An order of medium-sized acrocarpous mosses in which the leaves are ovate to lanceolate, with or without a nerve. The capsules are held erect and are usually ovoid with a double peristome; each capsule may be covered with a bell-shaped, often hairy, calyptra. They are found typically on trees; some species are found on rocks and walls. Genera include Orthotrichum and Ulota.
Subjects: Plant Sciences and Forestry.