Leptobryum (W. P. Schimper in Bruch & W. P. Schimper) Wilson, 1855.

Leptobryum has for years been considered a member of the Bryaceae, but recent work has transferred it to the small family Meesiaceae. This latter family has a cryptic feature which distinguishes its members from all other bryophytes. Every bryophyte has "axillary hairs," filamentous structures that arise from the immediate leaf axils. These hairs are typically so fugacious that one may not be able to find them on leafy stems from older parts of the plant. When young stems very near the growing apex are denuded of leaves these filamentous structures are revealed. One may find taxonomically useful observations of the length of the hairs and the number of constituent cells. The cells of the axillary hairs may be uniform throughout but more commonly the immediate basal cell may be different in shape and coloration from the remaining cells of that hair. Sometimes, also, the most distal cell of the hair may be differentiated. The Meesiaceae are unique among mosses in having strongly persistent axillary hairs with several basal cells strongly reddened.
see key to Meesia Etc.

Species included:
Leptobryum pyriforme (Hedwig) Wilson

Leptobryum pyriforme is easily recognized by the very long and narrow, crispate to flexuose leaves with a costa that broadens near the base and fills about 1/3 of the leaf base. It is a common plant on moist soil banks, seeps and springs away from the humid northwest coast of California. The pyriform, inclined capsules are almost always present and highly diagnostic.