4. Bartramia ithyphylla Bridel, Muscol. Recent. 2(3): 132, plate 1, fig. 6. 1803. (as Barthramia).
Bartramia ithyphylla var. breviseta (Lindberg) Kindberg; B. ithyphylla subsp. rigidula (Lindberg) Kindberg
Plants in lax to dense tufts, soft green to glaucous. Stems 1-3(-5) cm. Leaves stiffly erect when dry, spreading when moist, linear, 4-5 mm; base sheathing, shoulders well developed, firm; margins plane, serrulate to serrate distally, teeth paired distally; apex acuminate, subulate; costa excurrent, obscure in distal limb; basal laminal cell walls thin; medial and distal cells 25-45 × 5-7 µm, prorulae relatively low. Sexual condition synoicous; perichaetial leaves somewhat longer than stem leaves, 6 mm, more strongly clasping. Seta 0.8-3 cm, straight. Capsule inclined, subglobose to ovoid, asymmetric, 1 mm; operculum short-conic; peristome double; exostome teeth 300-400 µm, strongly transversely barred, finely papillose proximally, smooth distally; endostome basal membrane present, segments 1/2-2/3 length of teeth and somewhat adherent to them, smooth, cilia absent or rudimentary. Spores 25-40 µm.
Capsules mature Jul-Nov. Soil, rock; low to high elevations (0-3800 m); Greenland; Alta., B.C., N.B., Nfld. and Labr., Nunavut, Que., Yukon; Alaska, Calif., Colo., Idaho, Maine, Mich., Mont., Nev., N.H., Oreg., Utah, Wash., Wyo.; s South America (Argentina); Europe; e Asia (Taiwan); n, c Africa.
Bartramia ithyphylla is essentially an arctic-alpine species with disjunct populations in austral South America and the high mountains of Africa. In the flora area, the species frequents tundra and montane forest habitats with occasional occurrence at low to moderate elevations at northern latitudes. The glistening white leaf base is distinctive. The obscure costa in the distal limb and elongate distal laminal cells bearing low prorulae distinguish B. ithyphylla from other small species of the genus in the flora area. The distal leaves are sometimes divergent. Reports of Bartramia breviseta Lindberg [B. ithyphylla var. breviseta (Lindberg) Kindberg by some authors] from high elevations in Colorado likely represent misidentifications. In B. breviseta the capsules are overtopped by the perichaetial leaves (the seta is 1-3 mm), and the costa fills the acumen. As presently understood, B. breviseta is an arctic-alpine species of the Old World.