6. Barbula bolleana (Müller Hal.) Brotherus in H. G. A. Engler et al., Nat. Pflanzenfam. ed. 2. 10: 280. 1924.
Meesia bolleana Müller Hal., Bot. Zeitung (Berlin) 20: 338. 1862; Barbula ehrenbergii (Lorentz) M. Fleischer
Stems to 3.5 cm. Leaves lax when wet, short-ligulate to long-elliptic, 2-2.7 mm, base scarcely differ-entiated to ovate, not sheathing, margins plane or weakly recurved in proximal 1/2 to 3/4, apex narrowly to broadly obtuse, occasionally broadly acute, entire or weakly apiculate; costa percurrent to ending 2-3 cells before the apex, abaxial costal surface smooth, hydroids absent; distal laminal cells lax-walled, short-rectangular, 11-15 µm wide, 1-2:1, smooth or with low, simple papillae. Specialized asexual reproduction by fusiform or armed gemmae borne on stalks in leaf axils, to 185 µm. Sporophytes absent in the flora area.
Wet limestone, moist areas, wet rocks; moderate elevations; Ariz., Ark., Mo., N.Mex, Okla., Tex., Utah; Mexico; West Indies; Eurasia; n Africa; Australia.
The name Barbula bolleana replaces the long familiar B. ehrenbergii (J.-P. Frahm et al. 1996). The lax, largely smooth distal leaf cells, easily seen with the dissecting microscope, distinguish this hygrophilic species. Specimens with largely quadrate distal laminal cells may appear to have a weak intramarginal border along the leaf base of somewhat elongate cells. This species may be confused with Didymodon tophaceus, which generally has smaller leaf cells (9-12 µm wide) in fewer longitudinal rows (10-15 for D. tophaceus, 20-30 for B. bolleana), and often has long-decurrent leaf margins. Barbula indica is rarely also tufa forming. A specimen (Patterson 2185, NY) previously reported for Virginia (Frederick County) is Didymodon tophaceus.