Polytrichastrum G. L. Smith, 1971.

Older bryological works emphasized the gross morphology of the capsule in dividing those Polytrichaceae with abundant photosynthetic lamellae filling most of the abaxial surface of the leaf. This emphasis basically meant that plants with longitudinally ridged capsules were placed in the genus Polytrichum, and plants with smoothly cylindrical capsules were placed in Pogonatum. Subsequent work emphasizing patterns of exothecial wall ornamentation and stomatal presence or absence has shown that Polytrichastrum alpinum has stomatal and exothecial morphology appropriate to Polytrichum despite its cylindrical, unridged capsules. Most works list Polytrichum formosum and P. longisetum in Polytrichastrum, but we have become convinced that the overall morphological pattern of these latter two species place them more effectively in Polytrichum.
see key to Pogonatum Etc.

Species included:
Polytrichastrum alpinum (Hedwig) G. L. Smith