Calobryales Hamlin
Plants leafy, erect, fleshy and soft-textured, occasionally brittle, growing either as individuals or loosely gregarious, rarely forming extended patches, bright grass-green to yellowish green, lacking secondary pigments (except for antheridial walls), mostly 8–25 mm tall, growing by an apical cell with 3 nearly equal cutting faces, fundamentally triradial, varying from radially symmetric to anisophyllous (then with the third, reduced row of leaves dorsal). Branching copious, very irregular, exogenous-intercalary (the branch potentially originating from any ± mature, cortical cell), from all 3 rows of merophytes, resulting in a system of 3 types of shoots: ± horizontal, leafless, pale, rhizomatous axes, from which leafy branches may arise (or which may be gradually converted into erect, leafy axes); erect, leafy stems; geotropic, leafless stolons or flagella. Mucilage (slime) papillae conspicuous, of the stalked type, secreting massive amounts of mucilaginous matter. Axis terete, massive, often brittle and very fleshy, without a defined cortex, with a ± distinct central strand of smaller, elongated, leptodermous cells and a peripheral, parenchymatous, chlorophyllose cortical region. Rhizoids lacking. Leaves not passing through an embryonic 2-lobed stage, 3-ranked, gradually larger above or (sometimes) abruptly larger, the basal parts of leafy shoots microphyllous or leafless, the insertion transverse or ± succubous (then the third, often smaller, dorsal row of leaves remaining transversely inserted, the insertion line often acroscopically arched and laterally decurrent); leaves soft-textured and often brittle, unistratose or 2–3(4)-stratose only toward base, variable in shape, elliptical to broadly orbicular-subreniform to obovate-obdeltoid, in Haplomitrium ovalifolium sometimes bifid to the base into linear-lingulate lobes, the leaves entire or subentire. Cells non-collenchymatous, soft, relatively large, thin-walled. Oil-bodies distinct, small for cell size, several to many (to over 100) per cell, essentially homogeneous (when minute) to granular, colorless to pale brownish. Asexual reproduction absent.
Dioecious (autoecious in Haplomitrium monoicum). Antheridia numerous, fundamentally axillary, in axils of uppermost ♂ bracts, the ♂ bracts sometimes reduced to 3, then antheridia seemingly aggregated in a central group (disc) at summit of axis, which may be somewhat dilated, or, at times, a few scattered and arising some distance from leaf axils; antheridia (mature) yellowish or orange-red, mature antheridia clavate, the body gradually narrowed into stalk, the stalk elongate, 4-seriate. Archegonia with basically an identical disposition (and similar early ontogeny, see Schuster [1966b, 1967d]), aggregated (at least initially) in a terminal group on a dilated disc, situated fundamentally in the axils of the 3 uppermost leaves (but sometimes with scattered, reduced, lingulate “bractlets” between the archegonia), with archegonium production always resulting in swelling of the shoot tip, the archegonial development not involving apical cells (thus technically anacrogynous, and with absence of fertilization the shoot usually continuing growth); archegonia with neck extremely elongate, formed of 4 cell rows, the neck long, with 16–20(40) neck-canal cells, venter only slightly greater in diameter than neck at maturity. Archegonial venter dividing extensively periclinally subsequent to fertilization, forming a fleshy, cylindrical, green to yellowish, brittle, massive calyptra, the calyptra smooth and with unfertilized archegonia basal or nearly so (i.e., a true calyptra), or the unfertilized archegonia elevated on a shoot-calyptra, in either case the calyptra not surrounded by any protective device (involucres, perianth, marsupium, etc.). Fertilization of 1 or 2–3 archegonia per inflorescence may occur and 1 or 2–3 sporophytes per plant may result (the initial embryo formed not suppressing development of additional sporophytes).
Seta elongating capsule far beyond shoot-calyptra, notably massive, with a ± vestigial central strand of smaller cells. Capsule ellipsoidal-cylindrical, the wall 1-stratose (only the apical portion bistratose), the wall each with 1(2) annular, narrow, longitudinally oriented thickening bands; dehiscence usually imperfect and lateral (i.e., with lateral slits), often with 2 or 1 dehiscence lines, the capsule apex remaining fused and indehiscent.
Spores normally 16 per elater, 17–30 µm in diam., granulate to weakly reticulate; spore-elater ratio ca. 3:1. Elaters long, very slender and markedly attenuate, 6–10 µm in diam., gradually and only feebly tapered, usually with 2 narrow, yellowish spirals throughout much or all their length. Sporeling development of the Nardia type.
The Calobryales include relatively few species, all belonging to one family and genus.
