of acidic rock, often volcanic, brownish. Alar cells
not differentiated. Perigonial
leaves broader and shorter than vegetative leaves. Perichaetial
leaves similar to vegetative leaves. Sexual condition
autoicous or rarely dioicous. Capsule
striate; annulus compound; peristome teeth papillose or absent. Calyptra
mitrate to sometimes sub-cucullate. Brachydontium
is a genus of tiny, brownish plants of acidic rocks with striate capsules and peristomes ranging from well developed to completely absent. The species in the flora are olive green to brownish, stems ca. 0.6-2 mm; leaves 0.5-2.5 mm, erect, in ± two apparent rows, lanceolate-subulate, obtuse, leaf margins nearly entire, costa filling the subula; and the columella is not developed. They grow sympatrically on Mt. Rainier.