Sphagnum girgensohnii Russow

Species Classification

Sphagnum girgensohnii is a relatively robust species of peat moss.

General Coloration

It typically appears in shades of green to straw-coloured, with stems ranging from pale green to light brown. Unlike some related species, it never develops red colouration.

Capitulum Characteristics

At the top of each plant is a cluster of branches called the capitulum, which often takes on a yellowish-brown hue.

Stem Diameter

The plant's stem is fairly thick, measuring 0.6 to 1.0 mm in diameter.

Stem Cortex Structure

It is protected by an outer cortex layer made of 2–3 layers of transparent cells, each of which contains a distinctive large pore that is visible even under basic magnification.

Branch Arrangement

Branches grow in clusters of three, occasionally four, at intervals along the stem.

Branch Morphology

Each cluster typically has two spreading branches that can grow exceptionally long, often exceeding 25 mm, and one or two pale, cylindrical hanging branches. Near the top of the plant, these spreading branches become shorter and slightly club-shaped.

Stem Leaf Size & Posture

Stem leaves are upright and pressed closely to the stem, measuring 0.8–1.3 mm in length.

Stem Leaf Shape

They have a distinctive roughly rectangular or tongue-like shape, often slightly pinched in the middle, a form technically described as 'lyrate'.

Stem Leaf Apex & Border

Stem leaves have a wide, torn apex, and are bordered by elongated cells that become distinctly broader at the leaf's base.

Branch Leaf Size & Arrangement

Branch leaves, which are never arranged in five distinct rows, are fairly large for a peat moss of this type at 1.4–1.8 mm long.

Branch Leaf Shape

They have a broadly lance-like shape with strongly curved edges, giving them a somewhat pointed appearance.

Leaf Cell Types

These leaves contain two types of cells: small living cells that hold chlorophyll for photosynthesis, and larger, empty hyaline cells that help the plant store water.

Hyaline Cell Pores

The hyaline cells have numerous pores, particularly on their outer surface, which are critical for water absorption and movement within the plant.

Reproductive System

Sphagnum girgensohnii is dioecious, meaning male and female reproductive structures grow on separate plants.

Male Plant Characteristics

Male plants tend to be smaller than female plants, with shorter branches and distinctive brown reproductive structures.

Spore Capsule Occurrence

While the species can produce spore capsules, these structures are rarely seen.

Spore Characteristics

When spore capsules are present, their spores are yellowish-brown, slightly textured, and measure 23–27 micrometres (μm) in diameter.

General Habitat Conditions

Sphagnum girgensohnii typically inhabits shaded environments with a relatively thin peat layer and notable influence from mineral-rich water.

Preferred Habitat Types

Instead of growing in deep peat bogs, it favours damp woodland settings, grassy hillsides, and ditch edges. The species is particularly common along mire margins, especially in areas where fen woodland has developed.

Growth Form & Associated Trees

It characteristically grows above the water table, forming loose, scattered clumps or mats, often beneath birch (Betula) or willow (Salix) trees.

Additional Habitat Flexibility

The species has considerable habitat flexibility, and can be found in wet depressions in swamps and dwarf shrub heaths in addition to its typical woodland habitats.

Northern Range Habitat Adaptations

In its northernmost range, the species shows even greater habitat flexibility, extending into more open mire environments.

Subarctic Peatland Occurrence

It becomes particularly abundant in subarctic peatlands dominated by cotton grass (Eriophorum), where it frequently grows alongside another peat moss species, Sphagnum russowii.

Elevation Range

While primarily considered a subalpine species, it can be found from sea level to well above the tree line, reaching elevations of up to 2,200 m (7,200 ft) above sea level.

Global Distribution

The species has a wide distribution across the Northern Hemisphere.

European Distribution

In Europe, it occurs from Portugal to Russia, and from Svalbard to Italy and Spain, and is absent only from Moldova, Greece, and some smaller Mediterranean countries and territories.

European Regional Prevalence

While it can be found sporadically throughout lowland regions, it becomes notably more prevalent in upland and subarctic zones. It is particularly abundant in northern Iceland and across northern Scandinavia, where it ranks among the most common Sphagnum species.

British Isles Distribution Gradient

In the British Isles, there is a clear north-south gradient to its distribution: the species is rare in southern Britain but becomes increasingly common moving north through Wales and northern England, reaching its greatest abundance in Scotland.

Ireland Distribution

It is also widely distributed across Ireland, with a similar preference for northern regions.