Stems with hyalodermis absent. Leaves somewhat complanate, oblong-ovate, some asymmetric, concave; base weakly decurrent, abruptly narrowed and rounded to insertion; margins strongly serrate distally; laminal cell abaxial and adaxial surfaces bulging, smooth or low papillose-mammillose, papillae 1 per cell, weakly developed or absent, walls not collenchymatous. Specialized asexual reproduction by leaflike propagula smaller than more proximal leaves. Sexual condition autoicous; perigonia budlike in series down stem; perichaetial paraphyses of 8-15 cells. Seta single, reddish brown. Spores 10-15 µm, punctate.
SELECTED REFERENCES Blomquist, H. L. and L. L. Robertson. 1941. The development of the peristome in Aulacomnium heterostichum. Bull. Torrey Bot. Club 68: 569-584. Lowry, R. J. and W. C. Steere. 1946. A propaguliferous form of Aulacomnium heterostichum. Bryologist 49: 30-32.