1. Plants
large, tumid, leaves strongly concave; leaf apices broadly rounded;
margins entire; northern and high mountain species 4. A. turgidum
Aulacomnium turgidum is
a widespread species in the Arctic, and one of the most common
species in permafrost areas of Asian Russia growing in forest/lichen
communities above tree line. It has a restricted distribution in
European Russia where it extends only to the northernmost part of
the boreal zone, is very rare in most parts of the Urals and absent
in the Caucasus. Helpful features in identifying A. turgidum include its delicate texture and tumid plants. It can be confused
with A. palustre var. imbricatum; for distinguishing
features that separate the two taxa see discussion under A. palustre.
— Plants large, medium
sized or small, laxly foliate, leaves not or slightly concave; leaf
apices acute (rarely rounded in Arctic/alpine A. palustre var. imbricatum); leaf margins serrulate, serrate or subentire;
hygrophylic species found throughout Russia or rare terrestrial
species in western European Russia 2
2. Plants
5–10)–15) cm high; leaves straight or weakly flexuose when dry;
leaf apices gradually acuminate or slenderly acute; leaf margins
subentire; all stems without leafless distal ends, caducous leaves
absent 3. A. acuminatum
A widespread species in East
Siberia, extending westwards to Yenisei River (Central Siberia). Aulacomnium acuminatum is strongly associated with calcareous
areas where it may completely replace A. palustre, the
otherwise common Aulacomnium species in the region. Aulacomnium acuminatum is distinguished from A. palustre
by its larger plant size; stronger, rich-yellowish color; often
gradually acuminate leaf apices (enabling the species to be
recognized in the field); and complete absence of caducous leaves at
the shoot ends.
— Plants 1–7(–12) cm
high; leaves lexuose when dry; leaf apices acute; leaf margins
serrulate or serrate; sterile stems often with leafless, distal
ends, caducous leaves present 3
3. Plants
medium-sized, rarely small; leaf margins serrulate above, teeth
perpendicular to leaf margins; caducous leaves in terminal groups
and also sparingly scattered below, oblong, 4–5(–7) cells wide,
3–5-celled at base; widespread in Russia 2. A. palustre
This is a very widespread
Russian species throughout the Arctic to the steppe zone. It is
mainly a peat-bog species in the forest zone of European Russia, and
a common moss in all kinds of East Siberian forests. It can be
recognized by its yellowish-green color that strongly contrasts with
its bright-whitish costa, and leaves that are usually flexuose above
when dry. Plants from the Arctic and high mountains may have leaves
with rounded apices somewhat similar to those of A. turgidum:
these forms are often segregated as A. palustre var. imbricatum. This variety is best separated from A. turgidum by examining all the stem leaves. Inevitably,
collections of var. imbricatum have some acuminate leaves,
and some stems with terminal bundles of caducous leaves. Confusion
with A. androgynum is also possible, especially for very
small plants of A. palustre found in steppe areas with small
depressions of swampy Betula forests. In fact, in this
environment plants of A. palustre are even smaller than
average plants of A. androgynum. In these cases, the shape,
size and arrangement of cauducous leaves are the most important
features distinguishing the two species (see key).
— Plants small; leaf
margins coarsely serrate to serrulate above, teeth directed upwards;
caducous leaves in terminal groups only, elliptic to spindle-shaped,
2(–3) cells wide, 1-celled at base; rare species in westernmost
regions of European Russia 1. A. androgynum
Aulacomnium androgynum is known from scattered localities in the western parts of European
Russia (North West, the Caucasus, and Rostov Province), and is not
rare only in Kaliningrad Province. The species grows on wet peaty
and sandy soil banks and sandstones.