Hymenostomum inoperculatum H. A. Crum, Madroño 14: 74, figs. 1-6. 1957

Leaves elliptic, base weakly or not differentiated in shape, shoulders absent, distal laminal margins plane to erect, rarely incurved, apex plane, acute to rounded-acute, mucro usually strong, of (3-)4-6(-7) cells; costal adaxial stereid band smaller than the abaxial; distal laminal cells 8-10(-13) µm wide. Sexual condition dioicous (perigoniate plants mixed with the archegoniate). Seta elongate, 0.2-0.3 cm. Capsule cleistocarpic, short-elliptic, operculum weakly differentiated, peristome absent.

Capsules mature Feb. Garden, soil; moderate elevation; Calif.

Weissia inoperculata is known only from the type specimen (Stanford University, Santa Clara County). It has a gametophyte much like that of Trichostomum brachydontium and may prove better placed in Trichostomum. The operculum is weakly marked off by a ring of several rows of small cells.