Grimmia orbicularis

Gametophyte. Monoicous. Female: innermost perichaetial leaf 1.8 - 2.0 mm long, sheathing to mid-leaf or two third of leaf length, concave, sheathing part transparent, costa stout in upper part, excurrent in broad, nearly smooth hair-point; male: perigonia in branches far below perichaetium as multifoliate buds on short stalks, the concave, hyaline lower part of innermost perigonial leaf sheathing, suddenly narrowed to acute apical part, costa vanishing below apex, paraphyses present. Growth-form: cushions dense, compact, strongly attached to substrate, stolons originating from mostly present tomentum, leaflets scale-like, appressed to stem, apices patent, plants erect, branched, stems to 30 mm high, central strand developed. Leaves 1.0 - 1.5 mm long, crowded, appressed to stem when dry, bending backwards when moistened, erecto-patent when wet, from ovate leaf base lanceolate or elongate-lanceolate, broadest at mid-leaf, tapering to obtuse apex, hair-point very short to elongated, nearly smooth; leaf form in situ, at base concave, laminal part keeled, margins on both sides from below to above mid-leaf recurved, rarely on one side only; basal paracostal cells elongate-rectangular, walls nodulose, at margin some cell rows rectangular to quadrate, transverse walls thickened, smooth, cells in transitional part short-rectangular, sinuose, in upper laminal part isodiametric, lumina rounded; seen in transverse section, leaf base and lamina unistratose throughout, margin unistratose except one bistratose cell row on one, rarely on both sides near apex. Costa, seen on dorsal side, narrowed at leaf base, gradually enlarged to laminal part, excurrent into hair-point, costa, seen in transverse section, on dorsal side rounded, at insertion and leaf base mammillose, on ventral side in basal part widely channelled, in laminal part channelled, at insertion and in leaf base 4 guide cells, occasionally the 2 outer ones contiguous with the basal cells, in laminal part 2 guide cells, a median group of hydroids, vanishing below apical part. Sporophyte. Seta to 2.0 - 3.0 mm long, arcuate, vaginula 0.8 mm long, cylindrical, with ochrea. Capsule exserted, pendulous, ovoid, finely ribbed, exothecial cells elongated thin-walled, stomata large on base of capsule, neck none, annulus of two or three rows of cells, detaching easily as groups or singly. Calyptra cucullate. Operculum conical, mammillate, margin smooth, formed by a row of nearly isodiametric cells, in conical part cells irregular, walls thin. Peristome teeth erect, spreading when dry, broadly lanceolate, in upper half split into two or four divisions, occasionally imperfect or rudimentary, in places interconnected by anastomosis, separated down to the insertion, dorsal and ventral sides densely covered with fine papillae, trabeculae small, distant, in lower third sharply protruding. Spores 10 - 13 µm, smooth.