The Order Grimmiales is further organized into finer groupings including:
Plants acrocarpous or cladocarpous, small to large, usually olivaceous to blackish green, growing in rigid cushions, tufts, mats or patches. Stems erect, ascending, or prostrate, dichotomously to irregularly branched. Leaves erect and tightly appressed to crisped when dry, erect-spreading to patent when wet, lanceolate to ovate-lanceolate, less often ovate, oblong-ovate, linear, or lingulate, keeled, canaliculate, to broadly concave, smooth or sometimes longitudinally plicate, rarely with adaxial lamellae (Indusiella), margins plane, incurved, or variously recurved or revolute, mostly entire, 1- to multistratose, acuminate, acute to rounded-obtuse, typically with a hyaline awn, sometimes muticous, costa single, rarely spurred or forked distally (Codriophorus and Niphotrichum), usually strong, percurrent to excurrent, rarely subpercurrent, typically with one stereid band, distal lamina 1-2(-4) -stratose; basal cells quadrate to elongate, rarely oblate, straight, sinuose, or nodulose, basal juxtacostal and marginal regions usually differentiated, alar cells undifferentiated or hyaline; mid leaf cells quadrate to elongate, commonly sinuose or sinuose-nodulose, usually thick-walled. Perichaetia terminal on tips of stems or lateral branches; perichaetial leaves differentiated or not. Seta short to long, smooth or rarely papillose. Capsule usually erect, usually ovoid, obloid, cylindrical or cupulate, symmetric or rarely strongly ventricose at the base and gibbous, smooth or sulcate; annulus present or absent, often compound, deciduous or persistent; operculum mammillate to long-rostrate, sometimes attached to the columella after dehiscence (most Schistidium) ; peristome present, seldom rudimentary or absent, consisting of 16 teeth, lanceolate to linear, entire, perforated or cribrose, variously split into 2 or 3 unequal prongs or divided nearly to the base into two filiform somewhat paired segments, smooth or variously ornamented. Calyptra small to large, covering only the operculum to half or more of the capsule, cucullate, mitrate, or mitrate-campanulate, smooth or plicate, naked, sometimes papillose, slightly to distinctly lacerated or deeply lobed at the base. Spores globose, smooth or papillose. [more]
Plants small to robust, tufted or gregarious or cespitose, yellowish green to blackish. Stems erect or repent, simple or forked; central strand present; rhizoids reddish brown, inconspicuous; axillary hairs several per axil, with 2-3 short proximal cells and 5-7 long distal cells. Leaves erect to crispate or circinate when dry, ascending when wet, linear to oblong-lanceolate; margins entire to coarsely serrate, thickened distally; costa single, strong; medial cells isodiametric, in longitudinal files, 1-stratose, or 2-stratose in patches, smooth or slightly papillose. Specialized asexual reproduction rare, by axillary 1-seriate or branched gemmae. Sexual condition autoicous. Perigonia gemmiform, axillary on short naked stalks. Perichaetia terminal but quickly overtopped by innovations; leaves few, short. Seta single or several from a perichaetium, smooth, straight or flexuous. Capsule erect, exserted, brown, ovoid to cylindric, smooth or wrinkled when dry; stomata scarce, proximal on capsule, phaneropore; annulus revoluble; operculum slenderly rostrate; peristome single, teeth 16, short and broad to long and slender, smooth or densely papillose, mostly irregularly divided into 2-3 slender segments beyond the base. Calyptra mostly mitrate, lobed proximally, often deeply so, naked, smooth or plicate. Spores spheric. [more]
At least 105 species and subspecies belong to the Family Ptychomitriaceae.
More info about the Family Ptychomitriaceae may be found here.