se United States, Mexico, West Indies, Bermuda, Central America, South America, Eurasia, Africa, Pacific Islands.
Genera 21, species ca. 400 (3 genera, 3 species in the flora).
Pilotrichaceae are characterized by a double costa, stem hyalodermis usually present, undifferentiated alar region, and hairy calyptra (the calyptra is naked in the three species represented in the flora area). The leaves are usually complanate with a differentiation between lateral and dorsal or ventral leaves, and the seta is variously papillose to spinose. Recent changes in the circumscription of Pilotrichaceae were outlined by T. de Freitas Vaz-Imbassahy and D. P. da Costa (2009) and H. A. Miller (1971). W. R. Buck (1998) suggested two central lines of evolution in the family by which genera may be organized based on the presence or absence of a differentiated outer layer of inflated stem cortical cells (a hyalodermis), compared to an outer cortical layer of relatively thick-walled cells. Critical literature associated with the pre-1971 concept of Hookeriaceae in the flora area is that of W. H. Welch (1962, 1966, 1972).
|1||Laminal cells 1-papillose on both surfaces; leaf apices rounded-truncate, short-apiculate; setae scabrous; hyalodermis absent.||Callicostella|
|1||Laminal cells smooth or sometimes prorulose by projecting distal cell ends; leaf apices short- to long-acuminate; setae smooth; hyalodermis present or absent||> 2|
|2||Leaf apices short-acuminate; margins entire or serrulate distally; marginal cells forming border; laminal cells hexagonal or oblong-hexagonal, lax; hyalodermis present.||Cyclodictyon|
|2||Leaf apices slenderly long-acuminate; margins serrulate in distal 1/3; marginal cells not forming border; laminal cells narrow, long-rhomboidal to linear, not noticeably lax; hyalodermis absent.||Trachyxiphium|