''Polytrichum alpinum'', also known as Alpine haircap, is a species of

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

from the family

Polytrichaceae Polytrichaceae is a common family of mosses. Members of this family tend to be larger than other mosses with a thickened central stem and a rhizome. The leaves have a midrib that bears photosynthetic lamellae on the upper surface. Species in ...

. It is widely distributed and may be found growing among other moss species.

Description

''Polytrichum alpinum'' grows to form a loose, muddy green or bluish-green to brownish lawn. Typically, it grows up to high. The upright to erect stems often carry tufted branches of equal length above. In the lower part of the stems, leaves are small and scale-like, but become larger in the upper stem section – usually 7–10 mm long. The broad-oval, yellowish to brownish sheath at the leaf base is linear-lanceolate and occupies less than a third of the total leaf length. Leaf edges are serrated, fitting together when dry and bending back and protruding when wet. The leaf rib is cut in the upper part, emerging from the back as a short spike from the blade tip. The spreading part of the leaf is covered with numerous

lamellae Lamella (plural lamellae) means a small plate or flake in Latin, and in English may refer to: Biology * Lamella (mycology), a papery rib beneath a mushroom cap * Lamella (botany) * Lamella (surface anatomy), a plate-like structure in an animal * ...

(up to 40), these are in the middle of the leaf, 5-9 cells high. At the end cell, the lamella cross section is larger, ovoid and papillose. In the upper leaf, cells are square to rectangular, while lower down they become more elongated and have a hyaline (glassy) appearance. The moss is

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

and bears fruit fairly often, with spores maturing in summer. Spores are 14 to 20

µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

in size and have fine hairs. The spore capsule is up to long, red below and yellowish above. The olive-brown to black

seta In biology, setae (singular seta ; from the Latin word for "bristle") are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Annelid setae are stiff bristles present on the body. Th ...

(stalk) is slightly curved and tilted and has an elliptical-cylindrical shape. It has a clearly contrasting neck with numerous large, single-celled

stomata In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...

Ecology and distribution

The moss grows in a variety of habitats, from shaded to sunny sites, and on fresh to moist, nutrient-poor,

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adje ...

and base-poor soils. The moss may also colonise stony soil, boulders and snowy grikes above the treeline. In Europe, it is often found in arctic and

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

regions, while further south it is restricted to

montane Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...

landscapes and alpine areas. It is also found in Asia, Africa, the Americas, Australia, New Zealand and Antarctica.

Possible species confusion

In some localities, ''Polytrichum alpinum'' may be confused with ''

Pogonatum urnigerum ''Pogonatum urnigerum'' is a species of moss in the family Polytrichaceae, commonly called urn haircap. The name comes from "urna" meaning "urn" and "gerere" meaning "to bear" which is believed to be a reference made towards the plant's wide-mout ...

''. Key distinguishing features are that the spore capsules of the Alpine moss are at the bottom of large single-celled stomata; the capsule outer wall has smooth cells; the leaf sheath is much longer than that of ''Pogonatum urnigerum'' and the leaf blade is narrower and more spiky.

References

* Jan-Peter Frahm, Wolfgang Frey, J. Döring: Moss flora. 4 Edition, UTB Publishing, 2004, * Ruprecht Duell, Barbara Duell wonder: Moose determine easy and secure. Source Wiebelsheim & Meyer, 2008, * Fog, Philippi: The Moose Baden-Württemberg Volume 1 1 Edition, Ulmer Verlag, 2005, {{Taxonbar, from=Q15250107 Polytrichaceae