Barbula Hedw.

The following generic description is modified from Zander (1993).

Plants yellow-green to yellow-brown above, brown to black below, forming turves or tufts on soil or rock. Stems simple to irregularly branched, in cross-section central strand and sclerodermis usually present, hyalodermis occasionally present. Leaves erect-spreading to spreading when moist, appressed, incurved to weakly spreading, often contorted, or twisted around the stem when dry, often oblong-lanceolate, less commonly spathulate or ligulate, rounded to acute, usually mucronate; margins usually recurved in lower ½–⅔ of leaf, occasionally plane, entire, crenulate-papillose; upper laminal cells obscure, quadrate to short-rectangular, occasionally oblate, rarely isodiametric to elliptic, thin- to thick-walled, pluripapillose with complex papillae; upper marginal cells usually not differentiated; lower laminal cells usually differentiated, thin- to firm-walled. Costa stout, concolorous, usually excurrent, occasionally failing a few cells before apex; adaxial and abaxial superficial cells usually elongate or occasionally similar to adjacent laminal cells; in cross-section usually with 2 stereid bands. Laminal KOH colour reaction yellow.

Dioicous. Perichaetia terminal, with inner leaves variably differentiated, sometimes conspicuously sheathing the seta base. Perigonia terminal and lateral, bulbiform. Setae elongate. Capsules ovate to long-cylindric. Operculum long-conic. Peristome of 32 spiralled rami, strongly twisted to the right from a low basal cylinder. Spores 8–16 mm, smooth (in N.Z. species) to weakly papillose.

A cosmopolitan genus with some 200 species. Two species occur in N.Z., one of which, Barbula unguiculata, is almost certainly adventive. A third species, B. convoluta Hedw., is treated here as Streblotrichum convolutum (Hedw.) P.Beauv.

N.Z. species can be recognised by their yellow-green, stiff leaves (when dry), with the upper lamina deeply grooved adaxially along the costa and laminal cells pluripapillose; setae are elongate (to 35 mm in B. calycina), bearing subcylindric capsules with long-conic opercula, which have spirally arranged cells, and a twisted peristome ≥ length of the theca.

Members of the genus are commonly found on soil or rock in insolated sites.