Plants small to moderately large. Stems to 10 cm, usually shorter; central strand usually present. Stem leaves 0.6-2 × 0.3-0.8 mm, lamina 1-stratose; margins entire or nearly so to serrate; costa to mid leaf, percurrent, or rarely short-excurrent, narrower thanµm at base; medial laminal cells 10-60 × 5-15 µm.

Varieties 2 (2 in the flora): North America, Central America, South America, Eurasia, s Africa, Pacific Islands (New Zealand), Antarctica.

Subspecies varium occurs in a wide range of habitats and displays, accordingly, a wide range of morphological variability. Many features, like the presence of a central strand in the stem, leaf shape, and shape of the leaf apex, are plastic and depend on water availability.