20. Schistidium maritimum (Turner ex Robt. Scott) Bruch & Schimper, Bryol. Europ. 3: 102. 1845.
Grimmia maritima Turner ex Robt. Scott, Trans. Dublin Soc. 3: 158, plate 1. 1803; Schistidium maritimum subsp. piliferum (I. Hagen) B. Bremer
Plants in tufts, olivaceous, often brownish. Stems 0.8-5 cm, central strand absent. Leaves usually curved, sometimes erect, often somewhat contorted when dry, ovate-lanceolate to linear-lanceolate, keeled, (1.2-)1.5-2.6(-4) mm, usually 2-stratose distally; margins usually plane distally, recurved proximally, smooth or papillose, 2-stratose or 3-stratose, rarely 4-stratose distally; apices acute or blunt, sometimes ending in a short, fleshy, multistratose apiculus; costa percurrent, rarely excurrent as a short denticulate awn, with guide cells and one or two stereid bands, abaxial surface usually slightly papillose; basal marginal cells quadrate or short-rectangular, often trigonous; distal laminal cells isodiametric, rounded or angular, sometimes short-rectangular, 7-11 µm wide, smooth or weakly papillose, sometimes weakly bulging-mammillose, straight or slightly sinuose. Sexual condition autoicous. Capsule dark reddish brown or dark brown, ovoid, cupulate, or campanulate, 0.6-1.3 mm; exothecial cells usually angular, isodiametric, occasionally elongate, thick-walled; stomata present; peristome patent to revolute, 200-500 µm, red, papillose, often strongly perforated. Spores 15-30 µm, granulose.
Capsules mature late spring to early summer. Rocks within or near the spray zone along coasts; low elevations (0-20 m); Greenland; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., P.E.I., Que.; Alaska, Calif., Maine, Mass, Oreg., Wash.; Eurasia.
Schistidium maritimum is one of the easiest species of the genus to identify. Its usually 2-stratose distal laminae, well developed stereid bands, usually small and often campanulate capsules, and coastal habitat are distinctive. Subspecies piliferum, characterized by the presence of awns and a single stereid layer, is not recognized here; further study is needed.