Plants: to 1 cm. : Primary stems creeping, vegetative and fertile stems erect; leaves differentiated on vegetative and fertile stems. Stem: leaves erect-appressed when dry, ovate-ligulate to ovate-oblong, grading to lanceolate or ovate-lanceolate on fertile stems, 1.4–2.5 mm; margins recurved to near apex, entire; apex obtuse, acute to broadly acuminate near perichaetia; basal laminal cells quadrate to short-rectangular, walls thin, not nodose; distal cells 10–12 µm, uniformly 2-stratose, papillae 1–3 per cell, simple, low. : Specialized asexual reproduction absent. Sexual: condition gonioautoicous. Seta: 1 mm. Capsule: immersed, ovate-oblong, 1.5 mm, 8-ribbed entire length, constricted below mouth when dry; stomata immersed; peristome double; prostome absent; exostome teeth 8 splitting to 16, erect to spreading when dry, densely and coarsely papillose; endostome segments 8, occasionally rudimentary, of 1 or 2 rows of cells, smooth. Calyptra: short-conic, smooth, sparsely hairy, hairs papillose. Spores: 8–12 µm.
Dry sandstone boulders in dense chaparral. moderate elevations (600-700 m). Calif.
Of conservation concern. Only two species of Orthotrichum have immersed stomata and uniformly 2-stratose distal laminal cells; Orthotrichum hallii is a species of calcareous rock found sporadically throughout western North America, while O. kellmanii occurs on sandstone boulders only at a few sites in central California. Orthotrichum kellmanii is unique in the genus because it has prostrate stems that give rise to ascending vegetative and reproductive stems, the latter with differentiated leaves compared to vegetative stems. The stomata are found in the proximal half of the capsule, mostly covered by subsidiary cells; the exostome teeth are blunt and cribrose; and the endostome segments are fragile and delicate.
Plants: to 1.5 cm. Stem: leaves rigid, erect when dry, ligulate- to elliptic-lanceolate, to 5 mm; margins recurved from just beyond base to near apex, entire; apex obtuse to rounded-acute; basal laminal cells short-rectangular, walls thin, not nodose; distal cells 13–16 µm, 1-stratose, papillae 2 or 3 per cell, simple to 2-fid, high; marginal cells 2- or 3-stratose. : Specialized asexual reproduction absent. Sexual: condition gonioautoicous. Seta: to 0.5 mm. Capsule: immersed, short-cylindric to oblong-ovate, 1–2 mm, strongly 8-ribbed entire length, constricted below mouth when dry; stomata immersed, 2/3 to completely covered by subsidiary cells, cells projecting, inner walls thickened; peristome double; prostome absent; exostome teeth 8, reflexed, papillose to papillose-reticulate near apex; endostome segments 8, occasionally 16, well developed, of 1 row of cells, smooth or roughened. Calyptra: oblong, smooth, hairy, hairs papillose. Spores: 15–18 µm.
Dry granitic rock. moderate to high elevations (1100-1600 m). Calif.
Of conservation concern. Orthotrichum shevockii is known only from the southern Sierra Mountains. The species is distinguished by small, blackish tufts, obtuse to bluntly acute leaf apices, strongly multipapillose distal laminal cells, 2-stratose (or more) leaf margins, and completely immersed, strongly 8-ribbed capsules with immersed stomata, reflexed exostome teeth, well-developed endostome, and papillose calyptra hairs.