Bartramiaceae. Genus Bartramia

1. Leaf bases moderately differentiated, somewhat whitish, laxly sheathing; upper limbs with unistratose laminae and 2–3-stratose margins 2

— Leaf bases strongly differentiated, conspicuously whitish, tightly sheathing; upper limbs with bistratose laminae and unistratose margins 4

2. Setae short, equal to or slightly longer than capsules; capsules immersed or laterally emergent 2. B. halleriana

In Russia this species occurs sporadically in the Caucasus at middle elevations from 500 to 1800 m. It is very rare elsewhere. There are histo­rical records of the species from Kaliningrad Province and solitary localities in southern Karelia. This species differs from all other Russian species of the genus in having immersed or laterally emergent capsules. It grows mostly on calcareous rocks.

— Setae long, several times longer than capsule; capsules exserted 3

3. Plants in moderately dense tufts, glaucous to yellowish green; stems 2–7 cm long; leaves 4–6 mm long, curved to contorted and somewhat crisped when dry; capsules somewhat inclined, becoming asymmetric after spore release; widespread species in Russia 1. B. pomiformis

The most widespread and the most variable species of the genus, occurring in most mountain areas, while rare in extensive lowlands of the Middle European Russia and West Siberia. It grows on rocks and, rarer, on soil banks, only occasionally on trunk bases and decaying logs; in the mountains it mainly occurs at middle elevations, almost never crossing timber-line. The uppermost locality in Dagestan was at 2250 m a.s.l. At the same time, it grows in tundra in Taimyr. Although B. pomiformis prefers calcareous substrates, it can be found on various rock types, and on sand, humus and peat.

— Plants in dense tufts, glaucous to brownish green; stems 1–3 cm long; leaves 2–3.5 mm long, stiffly erect-appressed when dry; capsules erect, remaining symmetric after spore release; rare species in East Caucasus, not yet known but likely to occur in Russia [B. stricta]

This species is reported from Azerbaijan and probably occus in the Russian Caucasus, especially in Dagestan.

4(1). Leaves extremely fragile, often entirely deciduous; mountains of southern Siberia and Far East 4. B. deciduaefolia

This odd species has strongly caducous leaves. It is known from only a few localities in the South Siberian mountains. The gametangia and sporophytes of B. deciduaefolia are unknown in Russia.

— Leaves not fragile or with only fragile leaf tips; northern and mountain regions 3. B. ithyphylla

A recent revision of the B. ithyphylla-complex (Fransén, 2004) supported the separation of B. breviseta and B. deciduaefolia from B. ithyphylla, the most widespread arcto-alpine species of this group. However, the circumscription of these taxa in Fransén (2004) does not always correlate with Russian collections of the species, e.g., Russian specimens have eperistomate morphs with long leaves and elongate upper laminal cells. Furthermore, in Russian collections sexual condition does not correlate with peristomial characters as reported by Fransén. Russian plants with strongly fragile leaves, referred to B. deciduaefolia, also have upper laminal cells over 50 µm long, not 8–25 µm long as described by Fransén (2004). In southern regions of Russia Bartramia ithyphylla is a mountain species found in subalpine zones or higher elevations (e.g., in Altai from 1750 to 2900 m a.s.l. and in the Caucasus from 1850 to 2900 m a.s.l.). But in milder, oceanic climates, e.g., in Kaliningrad Province, as well as throughout the Arctic regions it occurs at sea level. It grows on rocks and soil, and is often present in deep rock-field niches.