Mosses of Central Florida 49. Stereophyllum radiculosum

The flat, dried leaves of  Stereophyllum radiculosum have a
conspicuously bulging midrib.
Photo by Juan David Parra, copyright MBG, posted on
Tropicos,  available under a Creative Commons License.

Stereophyllum radiculosum (Hooker) Mitten (Stereophyllaceae) forms thin, flat mats on the base of trees, exposed roots, stumps, logs, and limestone,  The distinctive flat leaves are attached uniformly around the stem (not flattened in a plane), elliptic-ovate in shape, and somewhat contorted when dry. The midrib is strong and markedly bulging, but does not reach the tip.  The leaf cells are small, roundish, and contains a single papillum (translucent bump). Spore capsules are erect to somewhat leaning,  asymmetrically egg-shaped, and arise from the bases of the leafy shoot on relatively short stalks (0.6-1.2 mm).

The leaning, egg-shaped spore capsule of Stereophyllum.
Photo by Juan David Parra, copyright MBG, posted on
Tropicos,  available under a Creative Commons License.

This species is widespread in the tropics; found in the U.S. only in Alabama, Texas, and Florida, where it occurs in the southern part of the state as far north as Citrus, Volusia, and Alachua counties.

Most other creeping species found on tree bases have somewhat flattened shoots, with leaves mainly on two sides of the stem, and capsules strongly bent to the side (Isopterygium or Haplocladium) or symmetrical and upright (Sematophyllum, Entodon).