Mosses of Central Florida 31. Ephemerum crassinervium

The tiny rosettes of Ephemerum crassinervium
appear scattered on a mass of green,
thread like stems (protonemata). Photo by Robert
A. Klips, Ohio Moss and Lichen Association.

Ephemerum crassinervium (Schwaegrichen) Hampe (Ephemeraceae) is a tiny moss that is often overlooked.  As the name implies, it is an ephemeral plant that pops up in disturbed soil along drying shorelines in the dry season, and occasionally on rotting logs.  The plants then disappear again as their habitat is flooded during the rainy season.

The tiny rosettes are only a few mm high, though the spreading leaves may be as much as 2.5 mm long.  Leaves are toothed in the upper 2/3 and papillose (with small, translucent bumps) at the tip.  The midribs are weak, sometimes not evident at the base.  Leaf cells are irregularly long-rectangular and lined up in vertical rows.

The spherical spore capsules are also tiny and
often overlooked. Photo by Robert A Klips,
Ohio Moss and Lichen Association.

The spore capsules, when they appear, are also barely noticeable, as they lack a stalk and remain nestled in the center of the rosette.  The spherical capsules do not open regularly like most other mosses, lacking the typical mouth, teeth, and lids, but eventually rupture irregularly.

Ephemerum crassinervium is found widely in eastern North America, west to Texas and Nebraska, north to Saskatchewan, Ontario and Quebec (but not known in Maine), with some reports from Oregon.  In Florida, it has been sparsely collected from the panhandle to Collier County.

Two additional species have been reported from Florida.  E. cohaerens has been even more sparsely collected throughout north Florida, but not yet in central Floirda.  It differs from E. crassinervium in the smoother cells of the leaf tip, and the leaf cells lined up in diagonal rows.

E. spinulosum has a similar distribution as C. crassinervium, with some in Hillsborough and Manatee counties; cells of the leaf tip are spiny as opposed to smooth or papillose.