||Plants lustrous, yellow-green or brownish, pinnately to sub-pinnately branched, stem and branch apices usually turgid, ± terete; axillary hairs with one short, brown basal cell and 2--6 longer hyaline cells; pseudoparaphyllia foliose. Stems flattened in cross section, central strand present, sometimes poorly developed, inner cortical cells large, thin walled, outer cortical cells in 3--4 layers of smaller thick-walled cells, hyalodermis present, outer walls thin; rhizoids arising from ventral stem surface near leaf bases. Stem and branch leaves dimorphic, ± concave, apex of both usually cuspidate or, if not, obtuse;stem leaves ovate, broad, short, apex acute and weakly cuspidate to rounded, costa short and double, mostly inconspicuous or absent, alar cells abruptly inflated, cells immediately above alar group often ± quadrate and thicker-walled, inner basal cells shortly elongate, thick-walled; branch leaves entire, lanceolate, longer than stem leaves, apex usually cuspidate; laminal cells in leaves of both types variable, short and weakly sinuose at apex, long-flexuose-sinuose at mid leaf, short and wide with walls pitted at base, stem leaves ovate, branch leaves lanceolate; alar cells inflated and in a conspicuous ± auriculate group; costa short and double or absent. Sexual condition dioicous. Perichaetia in leaf axils, inner leaves becoming long-lanceolate, plicate, margins weakly serrate toward the base, costa absent, perichaetial leaf apices flaring at archegonial maturity. Perigonia axillary, budlike, apices of perigonial leaves flaring. Capsule arcuate, horizontal, exothecial cells collenchymatous, annulus differentiated, in 2--4 rows, operculum conic-apiculate; exostome teeth bordered, outer surface papillose distally and striolate basally, endostome basal membrane high, segments keeled, perforate, cilia 2--4. Spores finely punctate.
[Diminutive of Calliergon, Greek, kallos, beauty, and ergon, a work or product, hence a small work of beauty