Sphagnum annulatum

↑ Photo source: Kjell Ivar Flatberg, publisher: NTNU Vitenskapsmuseet, License CC BY 4.0

Description¹ | ² | ³ | ⁴ | ⁵

General

Sphagnum annulatum is relatively constant in both macroscopic and microscopic characters. But is still varying from small to moderate, from green, yellow to chestnut-brown to sometimes orange-brown or red-brown. It’s always glossy looking when moist (due to the many poresComplete opening through the wall of a hyaline or cortical cell, often visible as a round hole and sometimes occurring in rows in its branch leaves). A completely green color variant exists but is rare.

Commonly it has:

• A very prominent top bud which is never hidden by its inner capitulumSmall head; in Sphagnum, a compact cluster of young branches at the top of the gametophyte stem branches
• A clearly star shaped capitulum
• A brown or orange colour
• A mostly pale stem with longer than wide stem leaves, which stick out from the stem
• Divergent branches with very short leaves at the base
• Branch leaves which are unranked and erecto-patentOrientation of leaves or branches that stands between upright (erect) and spreading outward (patent), typically at a moderate angle from the stem to imbricateOf or pertaining to branch leaves firmly inserted into each other and overlapping on the branch; overlapping each other like roof tiles in arrangement
• Branch leaf hyaline cellsLarge, empty, transparent leaf cells in Sphagnum, specialized for water storage; also called hyaline cells or leucocysts very porosehaving pores and in rows of one to two throughout and on both sides of the leaf
• Undifferentiated stem cortexouter layer or layers of stem or branch, consisting of comparatively large, thin-walled cells

Capitulum

The capitulum forms a slightly to distinctly stellateCapitulum in which the outer and middle branches form a clear five-pointed star when viewed from above head. When viewed from above the outer branchesThe outermost and longest branches of the capitulum are straight to somewhat laterally curved. And when viewed from the side they are distinctly arcuato-decurvedarched and bent downwards . The apical budStructure located in the centre of the capitulum which gives rise to all the organs; may be: obvious, visible but not obvious, prominent, conical or hidden among developing branches is well developed and usually equals or exceeds the inner branchesShort, often erect branches in the centre of the capitulum in length, remaining clearly exposed rather than concealed. In male plants during autumn, the capitulum becomes strongly convex and bears short, clavateclub-shaped: narrowed towards the base and broader near the apex antheridial branchesbranch bearing antheridia .

Branches

Fasciclestuft or group of branches originating at the same point on a stem are usually situated loosely on the stem. Most of them carry two divergent branches with one or two pendent branchesBranches in a fascicle that hang downwards and are ± appressed to the stem that most often stick a little out from the stem.

The divergent branches often curve towards the ground and tend to be thickest at the middle section of the branch. The branch axis is often slightly reddish near the base.
Along a divergent branch the branch leaves near the proximalNear the base or attachment point (opposed to distal) end are much shorter than those in the middle, where they are broadly ovate-lanceolateLeaf shape intermediate between ovate and lanceolate, broadly egg-shaped near the base but tapering into a longer, narrower tip , and in S. annulatum these tiny leaves is often very noticable (with a loupe). Divergent branch leaves are unranked and can range from erecto-patent to commonly clearly imbricate. Sometimes with few to many leaves appearing straight to very subsecundLeaves mostly curved toward one side, looking slightly one-sided but not as strongly as in fully secund leaves .

The pendent branches are normally more slender and shorter than the divergent branches.

Stem

The stem is pale, sometimes with reddish-orange-lightbrown portions, especially when growing very wet and it being late in the season.

The stem leaves are more or less spread away from the stem itself and are longer than wide. They are lingulatetongue-shaped to lingulate-triangular, medium to very curved concavely, and more often than not broadest at or just above the base. The tip is usually acute to a slightly bluntly acute, and only rarely narrowly truncate-erose at the very tip. On male plants the stem leaves are relatively shorter and broader, with a more obtuse apex than in females.

Variation

In the field it behaves as a fairly phenorigidDescribing a species whose visible form (size, colour and structure) changes little across different habitats or ecological conditions species. Both the macroscopic and microscopic characters stay quite constant for a sphagnum species. Within miresWetland with at least some peat and living peat-forming plants; peat may be shallower than the depth often required to classify a site as peatland it usually occupies only a short bit of the “dry-wet” ecogradientGradual change in environmental conditions, such as moisture or nutrients, across space, usually accompanied by predictable shifts in species composition . Under its ordinary minerotrophicReceiving water and dissolved minerals from groundwater or surface water that has contacted mineral soil or rock mire conditions the plants are mostly medium sized and chestnut-brown, as seen in the images at the top of this page. The capitulum branches look relatively straight when viewed from above.
In fenMinerotrophic peatland fed by groundwater or surface inflow from mineral soils, usually with sedges and brown mosses and little or sparse tree cover vegetation, especially in subalpine and alpine areas, plants are often dark orange to red-brown with a more strongly curved capitulum and more imbricate divergent branch leaves.
There also exists a very rare permanently green morph.

Variation - Macroscopic Pictures { .collapse }

Below are some examples of how S. annulatum can look in the field. All of the plants shown are non-permanent forms that change with the season, the local “dry-wet” gradient and the “poor-rich” gradient.

Habitat { .collapse }

S. annulatum works as an indicator of minerotrophic wetlandsPeatland receiving most water and dissolved minerals from groundwater or surface inflow that has passed through mineral soil; usually less acidic and more base-rich than ombrotrophic bogs. Fens are minerotrophic peatlands , and it is not found in ombrotrophic bogsPeatland whose water and nutrient supply come mainly from precipitation, giving chemistry and vegetation typical of bogs. Often functionally equivalent to a bog surface .

The species is predominantly a mire plant. In Norway it also turns up in subalpine and low alpine areas, where it can grow in spring and snow-bed vegetationPlant communities occurring where late-lying snow persists into summer, producing short, cool and moist growing conditions on the ground on very shallow peat. It is only found in minerotrophic conditions. It is most typical of sloping fens, but can also occur in topogenousOf a peatland forming in a topographic depression, with part of its water supply provided by the surrounding regional water table fens.
Along the “poor-rich” vegetation gradient its ecological range is fairly narrow: it is found mainly in intermediate fensFen with moderate base status and species richness, between poor and rich fens along the minerotrophic gradient , occasionally in transitional poor fensFen with modest base and nutrient supply, chemically and floristically between ombrotrophic bogs and richer fens and only rarely in rich fensFen with relatively high base saturation and many calciphilous plants; chemically buffered and species-rich but not always strongly nutrient-rich . On the “hummock-mud-bottom” vegetation gradient it usually forms high-level carpetsVery soft peat surface dominated by bryophytes with sparse sedges, often from a few centimetres below to a few centimetres above the water table; footprints remain visible for a long time and lawnsNearly level peat surface with dense graminoids (grass like plants) and a diverse moss layer, usually about 5–20 cm above the water table and firm enough that footprints disappear quickly ; it is less often seen in wetter carpets and only seldom at the beginning of the hummockPeat surface raised roughly 20–50 cm above the wettest level, often with drier Sphagnum, lichens and dwarf shrubs level.

Macro Pics

↑ Photo source: Kjell Ivar Flatberg, publisher: NTNU Vitenskapsmuseet, License CC BY 4.0

↑ With “pa” S. papillosum, “li” S. lindbergii and “pu” S. pulchrum. Photo source: Kjell Ivar Flatberg, publisher: NTNU Vitenskapsmuseet, License CC BY 4.0

↑ Photo source: Kjell Ivar Flatberg, publisher: NTNU Vitenskapsmuseet, License CC BY 4.0

↑ Classic thickest in the middle of the divergent branches look

↑ Stem with stem leaves and some branches still attached

↑ Stem with stem leaves attached. Photo source: Kjell Ivar Flatberg, publisher: NTNU Vitenskapsmuseet, License CC BY 4.0

Micro Pics

↑ Lingulate-triangular with a rounded and sometimes eroded tip. Hyalocysts fibrillose in the tip.

↑ Stem leaf to the left, branch leaf to the right. Photo source: Kjell Ivar Flatberg, publisher: NTNU Vitenskapsmuseet, License CC BY 4.0

↑ Stem leaf at the top (notice the fibrillose hyalocysts towards the tip), branch leaf in the middle and folded branch leaf at the bottom

↑ Hyalocysts of the bottom of the branch leaf most often has a similar length as in the middle section of the branch leaf

↑ Pores on convex side of the branch leaf in one to two rows. Very few or no interfibrillose intervals without pores

↑ Often very symmetrical looking pores in branch leaf

↑ Always has a good amount of pores on the concave side of the branch leaf, but these are often hard to see without heavy staining

↑ Stem cross section. Notice the undifferentiated and/or poorly developed cortical cells

Lookalikes { .collapse }

This lookalikes block covers the Sphagnum annulatum complex in Europe: S. annulatum, S. jensenii, S. balticum and S. majus. With field experience, these can often be separated by capitulumSmall head; in Sphagnum, a compact cluster of young branches at the top of the gametophyte stem structure, but the species can overlap in macromorphology along the “dry-wet” ecogradientGradual change in environmental conditions, such as moisture or nutrients, across space, usually accompanied by predictable shifts in species composition , so microscopy can be required to be sure. Especially with S. annulatum and S. jensenii. S. annulatum is a parent species of S. jensenii (together with S. balticum) and of S. majus (together with S. cuspidatum).

At a glance (field / hand lens)

• S. annulatum: usually the most clearly stellateCapitulum in which the outer and middle branches form a clear five-pointed star when viewed from above , with a distinct exposed apical budStructure located in the centre of the capitulum which gives rise to all the organs; may be: obvious, visible but not obvious, prominent, conical or hidden among developing branches ; glossy chestnut colour and arcuato-decurvedarched and bent downwards branches are supportive but can overlap with lookalikes.
• S. jensenii: usually the largest and most variable in size across wetness; the apical bud is often partly concealed, the capitulum is most often flatter with straighter (and often longer) branches than in S. annulatum and S. majus, and longer branches with leaves less imbricateOf or pertaining to branch leaves firmly inserted into each other and overlapping on the branch; overlapping each other like roof tiles and less clearly rankedArranged in distinct rows or ranks (e.g., branch leaves appearing lined up in rows along the branch) than in S. balticum.
• S. balticum: usually flatter-headed, with straighter branches and more clearly rankedArranged in distinct rows or ranks (e.g., branch leaves appearing lined up in rows along the branch) branch leaves; often in nutrient-poor mire habitats, including both ombrotrophicDescribes peatland surfaces nourished almost entirely by rain and snow, with little or no groundwater influence, leading to acidic, nutrient-poor conditions and minerotrophicReceiving water and dissolved minerals from groundwater or surface water that has contacted mineral soil or rock settings.
• S. majus: usually less clearly stellate, with more laterally curved branches and a more messy looking capitulum; branches and branch leaves often more subsecundLeaves mostly curved toward one side, looking slightly one-sided but not as strongly as in fully secund leaves and scythe-like than in other members of this complex.
• Practical caution: some guides claim that one pendent branchBranches in a fascicle that hang downwards and are ± appressed to the stem is typical of S. balticum and two of S. jensenii, but this varies with habitat in for all species in the complex.

Species notes

S. annulatum { .collapse }

Key field marks (summary)

• Stellate capitulum.
• Slightly curved capitulum. Male plants strongly curved in autumn.
• Small to medium in size.
• Brownish to yellowish, glossy colour.
• Distinctly exposed apical bud.
• Divergent branches are often distinctly curved downwards and often thickest in the middle part of the branch.
• Stem leaves are normally markedly longer than wide.
• Minerotrophic, enjoys medium rich mire sites like sloping and string-flark fens.

S. annulatum vs S. jensenii

• S. annulatum is usually less robust, with a clearer exposed apical bud and a more regularly 5-radiate head than S. jensenii.
• Divergent branch leaves in S. annulatum are typically more imbricate, less disorderly, more concave, and much smaller near the proximalNear the base or attachment point (opposed to distal) end of the branch.
• Branches in S. annulatum are more arcuato-decurved than in S. jensenii.
• Stem leaves in S. annulatum are markedly longer than wide, and in S. jensenii they are more broadly triangular to tringular-tongueshaped and not markedly longer than wide.
• Stem cortexouter layer or layers of stem or branch, consisting of comparatively large, thin-walled cells is often weakly differentiated or nearly undifferentiated in S. annulatum, unlike the clearer differentiation in S. jensenii.
• Branch leaves in S. annulatum have more uniform hyalocyst length between basal and middle part, while in S. jensenii hyalocysts are normally markedly longer in the basal part than in the middle part.
• Branch leaves in S. annulatum often have more and smaller pores on the convex surface. Towards the apex of the leaf, ringed pores are more commonly occurring and commissural pseudopores are rarer than in S. jensenii.

S. annulatum vs S. balticum

• S. annulatum has a much more distinct apical bud and with much less inwards curved inner branchesShort, often erect branches in the centre of the capitulum than S. balticum.
• Capitulum branches in S. annulatum are more narrowly tapering, whereas S. balticum tends to be flatter with straighter, more obtusely tapering branches.
• Capitulum branches in S. annulatum are more arcuato-decurved than in S. balticum.
• Branch leaves in S. annulatum are less ranked than in S. balticum
• Stem leaves in S. annulatum are normally longer and narrower than in S. balticum.
• Habitat overlap does occur but S. annulatum is more often found in medium-rich fens, while S. balticum is more typical of nutrient-poor or ombrotrophic mire vegetation.
• Branch leaves in S. annulatum have many more pores, in one to two rows on the convex surface, which S. balticum always lacks.

S. annulatum vs S. majus

• S. annulatum’s capitulum is typically more clearly stellate
• S. annulatum’s capitulum is less domed and more often with arcuato-decurved capitulum branches.
• S. annulatum has a more distinct apical bud
• S. annulatum has straighter (less laterally curved) overall structure than S. majus.
• Divergent branches in S. annulatum lack the distal sigmoid tendency often found towards the end of S. majus’s branches.
• S. annulatum’s branch leaves are more imbricate, less irregular and less subsecund.
• S. annulatum enjoys medium-rich fen habitats, while S. majus is more typical of nutrient-poor mire vegetation.
• S. annulatum has many free pores on the concave surface of divergent branch leaves. S. majus can have some commissural pores on the concave surface, but free pores are normally absent.

Microscopy (key separators for S. annulatum)

• VS S. jensenii: In divergent branch leaves, hyalocysts are usually of more uniform length between basal and middle portions (contrasting with the much longer basal hyalocysts in S. jensenii as compared to towards the middle of the leaf).
• VS S. jensenii: Stem cortex is often weakly differentiated or nearly undifferentiated in S. annulatum, while in S. jensenii it is more clearly differentiated.
• VS S. majus: On the concave surface of divergent branch leaves, many free pores are typical in S. annulatum. Contrasting with S. majus’ lack of free pores on the concave side of the divergent branch leaves.
• VS S. balticum: In both concave and convex surfaces of divergent branch leaves, S. annulatum always has a lot more pores than S. balticum. On the convex surface, S. annulatum typically has two (to one) rows of free laying pores, which S. balticum lacks.

S. jensenii { .collapse }

Key field marks (summary)

• Stellate capitulum
• Flat to curved capitulum. Male plants strongly curved in autumn.
• Moderatly robust to large. Usually larger than others in this complex, but also more variable than them along the wetness gradient. Small in drier sites or low hummocks.
• Yellow-brown to light or dark brown in colour
• The apical bud is often partly concealed by inwards curved inner branches and will be varyingly visible.
• Divergent branches are often mostly straight and curving downwards towards the apex.
• Stem leaves are triangular to tringular-tongueshaped, a bit longer than wide.
• Minerotrophic, enjoys string-flark fens.

S. jensenii vs S. annulatum

• S. jensenii is typically more robust, with larger, less regularly 5-radiate capitula and a less exposed apical bud, which is often partly or fully concealed by inwards-curved inner branches.
• S. jensenii is much more variable in response to wetness, showing greater changes in size and leaf length along the “dry-wet” ecogradient.
• Divergent branches in S. jensenii are usually longer, more evenly thick, and mostly straight to slightly curved downwards.
• Divergent branch leaves in S. jensenii are less imbricate, more disorderly, less concave, and less reduced near the proximal end of the branch.
• Hyalocysts in the divergent branch leaves of S. jensenii are markedly longer in the basal part than in the middle part.
• On the convex surface of divergent branch leaves, S. jensenii has fewer but larger hyalocyst pores on average, and commissural pseudopores are relatively common towards the apex.
• Stem cortex is more clearly differentiated in S. jensenii.
• Stem leaves in S. jensenii are broader triangular to triangular-tongue-shaped and only a bit longer than wide.

S. jensenii vs S. balticum

• S. jensenii is typically more robust and a more distinct, more often visible apical budStructure located in the centre of the capitulum which gives rise to all the organs; may be: obvious, visible but not obvious, prominent, conical or hidden among developing branches .
• Divergent branche leaves in S. jensenii with leaves less imbricateOf or pertaining to branch leaves firmly inserted into each other and overlapping on the branch; overlapping each other like roof tiles , more disorderly, and less clearly rankedArranged in distinct rows or ranks (e.g., branch leaves appearing lined up in rows along the branch) .
• Stem leaves in S. jensenii are often longer and less concave.
• On the convex surfaceabaxial surface (of a leaf) of divergent branch leaves, S. jensenii usually has more numerous hyalocyst pores.
• The number of pendent branchesBranches in a fascicle that hang downwards and are ± appressed to the stem per fascicle is variable in both species and not reliable for separation.
• Habitat overlap occurs, but S. jensenii does not grow in ombrotrophic habitats.
• Similarity is most problematic in drier hummock habitats, where S. jensenii can appear more slender and overlap with S. balticum in color and size; in typical wet carpet habitats, S. jensenii is usually larger and more robust.

S. jensenii vs S. majus

• S. jensenii is typically more robust.
• Often similar capitulum colour
• S. jensenii typically flatter and more clearly 5-radiate capitulum, with less laterally curved capitulum branches and longer, straighter outer capitulum branches.
• Divergent branch leaves in S. jensenii are usually less subsecundLeaves mostly curved toward one side, looking slightly one-sided but not as strongly as in fully secund leaves and less involuteRolled inwards .
• On the concave surface of divergent branch leaves, many free pores are present in S. jensenii.

Microscopy (key separators for S. jensenii)

• In divergent branch leaves, hyalocysts are often markedly longer in the basal part than in the middle part; this contrasts with the more uniform pattern in S. annulatum.¹
• On the convex surfaceabaxial surface (of a leaf) , commissural pseudoporesThin or partially resorbed spot in a hyaline cell wall that resembles a pore but is not fully perforated; also called an imperfect pore by some authors. are commonly present (especially apically), while they are rare in S. annulatum and only occasional in S. majus.¹
• On the concave surface of divergent branch leaves, many pores are usually present (contrasting with typically pore-poor S. majus subsp. majus).¹
• Pore number and size vary with habitat and sex, so combine pore traits with branch/leaf architecture for reliable separation.¹

S. balticum { .collapse }

Key field marks (summary)

• Usually flatter-looking and more slender than S. jensenii, with a less distinct (often hidden) apical bud in this complex.^{1 2 4}
• Outer capitulum branches tend to look straighter and more obtuselyBlunt; (opposed to acute) tapering than those of S. jensenii and especially S. annulatum.^{1 4}
• Divergent branch leaves are often more clearly rankedArranged in distinct rows or ranks (e.g., branch leaves appearing lined up in rows along the branch) and more imbricate; stem leaves are described as shorter, broader and more concave than in S. annulatum.^{1 2}
• Most typical in nutrient-poor mire vegetation, and common in both ombrotrophicDescribes peatland surfaces nourished almost entirely by rain and snow, with little or no groundwater influence, leading to acidic, nutrient-poor conditions and minerotrophicReceiving water and dissolved minerals from groundwater or surface water that has contacted mineral soil or rock settings; treat habitat as supportive rather than decisive.^{1 2}

S. balticum vs S. annulatum

• S. balticum typically has a flatter head and less distinct apical bud, whereas S. annulatum more often shows a distinct exposed apical bud.^{1 2}
• Outer branches in S. balticum are usually straighter and more obtuselyBlunt; (opposed to acute) tapering; S. annulatum is more arcuato-decurved and more narrowly tapering (attenuateOf or pertaining to the tip of an organ which tapers; narrowly tapering ).^{1 2}
• Stem leaves in S. balticum are described as shorter/broader and more concave than in S. annulatum in comparison texts.^{2 4}

S. balticum vs S. jensenii

• S. balticum is usually less robust, with a flatter capitulum and a less distinct apical bud; S. jensenii is typically larger, with a more distinct apical bud.^{1 4}
• Divergent branch leaves in S. balticum are generally more ranked/imbricate, while S. jensenii tends to show less imbricate, more disorderly leaf arrangement.¹
• The number of pendent branchesBranches in a fascicle that hang downwards and are ± appressed to the stem (often one vs two) varies with habitat in both taxa and is not reliable on its own.^{1 4}

S. balticum vs S. majus

• S. balticum tends to look flatter with straighter branches/leaves, while S. majus is usually less clearly stellate with more laterally curved branches and a more irregular habit.^{1 5}
• In S. balticum, one pendent branch is common in drier, nutrient-poor habitats, but counts vary between one and two; in S. majus, pendent branch is more often two.^{1 5}

Microscopy (key separators for S. balticum)

• Compared with S. jensenii, S. balticum usually has fewer hyalocyst pores on the convex surfaceabaxial surface (of a leaf) of divergent branch leaves.¹
• ChlorocystsNarrow, photosynthetic cell between hyaline cells in a Sphagnum leaf in cross section tend to be somewhat more ovate / less ovate-triangular than in S. jensenii in comparison material.¹
• Pore traits vary with habitat; use pore number and type together with macromorphology rather than as a single decisive character.¹

S. majus (subsp. majus) { .collapse }

Key field marks (summary)

• Usually a less clearly stellateCapitulum in which the outer and middle branches form a clear five-pointed star when viewed from above , more domed head with laterally curved capitulum branches and an apical budStructure located in the centre of the capitulum which gives rise to all the organs; may be: obvious, visible but not obvious, prominent, conical or hidden among developing branches that is usually indistinct or hidden.^{1 5}
• Branches and branch leaves often look more irregularly bent, with leaves tending to be more subsecundLeaves mostly curved toward one side, looking slightly one-sided but not as strongly as in fully secund leaves and involuteRolled inwards and less densely imbricateOf or pertaining to branch leaves firmly inserted into each other and overlapping on the branch; overlapping each other like roof tiles than in other members of this complex.^{1 2}
• Similar in robustness to S. annulatum (though S. annulatum can look more slender), less robust than S. jensenii; stem leaves are characteristically narrow and divergent branch leaves relatively long.¹
• In S. annulatum, S. jensenii, and S. balticum, the number of pendent branchesBranches in a fascicle that hang downwards and are ± appressed to the stem per fascicle overlaps between one and two and has limited diagnostic value (with habitat-related tendencies); in S. majus, pendent branch number also varies from one to two.¹

S. majus vs S. annulatum

• S. majus is often less clearly stellate with more laterally curved capitulum branches, and it often lacks a distinct exposed apical bud.^{1 5}
• Divergent branches in S. majus often show a distal sigmoid curve (not emphasized for S. annulatum), and branch leaves are described as narrower, more spreading and less densely imbricate in comparison texts.^{1 2}

S. majus vs S. jensenii

• S. majus is described as less clearly stellate with more laterally curved branches, while S. jensenii is flatter-looking with longer and straighter outer branches in these comparisons.⁵
• Branch leaves in S. majus are described as more subsecundLeaves mostly curved toward one side, looking slightly one-sided but not as strongly as in fully secund leaves and involuteRolled inwards ; S. jensenii is generally more robust overall.^{1 5}

S. majus vs S. balticum

• S. majus is described as less clearly stellate with more laterally curved capitulum branches, while S. balticum is flatter-looking with straighter branch leaves in these comparisons.⁵
• Comparison texts also emphasize that S. balticum often has one pendent branch in drier, nutrient-poor habitats but more often two in wetter, richer sites, whereas S. majus shows pendent branch numbers varying from one to two.^{5 1}

Subspecies note: subsp. norvegicum vs subsp. majus

• Artsdatabanken contrasts subsp. norvegicum with subsp. majus as having lighter, greyer heads, broader branch leaves, and broader stem leaves with a more obtuseBlunt; (opposed to acute) apex.⁵

Microscopy (key separators for S. majus)

• Stem cortexouter layer or layers of stem or branch, consisting of comparatively large, thin-walled cells is more differentiated than in S. annulatum.¹
• On the convex surfaceabaxial surface (of a leaf) of divergent branch leaves, S. majus typically has fewer, larger and less regularly arranged perfect pores than S. annulatum; ringed perfect porespore surrounded by a ring of thickened cell wall are absent or rare in the apical portion (common in S. annulatum).¹
• Compared with S. jensenii, hyalocystLarge, empty, transparent leaf cells in Sphagnum, specialized for water storage; also called hyaline cells or leucocysts pores on the convex surface are somewhat larger in S. majus, and commissural pseudoporesThin or partially resorbed spot in a hyaline cell wall that resembles a pore but is not fully perforated; also called an imperfect pore by some authors. are only occasional (common in S. jensenii).¹
• On the concave surface of divergent branch leaves, pores are described as lacking or nearly so in S. majus, versus many pores in S. annulatum and S. jensenii.¹
• ChlorocystsNarrow, photosynthetic cell between hyaline cells in a Sphagnum leaf in cross sectioncut made to an organ to show the internal structure are usually trapezoidal-rectangular and exposed or only slightly enclosed on the concave side; in S. annulatum they are smaller/more ovate, and in S. jensenii narrower and more ovate-triangular with broader enclosure on the concave side.¹
• Stem leaf hyalocysts are more fibrillosebearing fibrils than in S. jensenii (which has less fibrillose and more porose hyalocysts in upper stem leaves); stem leaf cell and pore structure is described as similar between S. majus and S. annulatum.¹
• Pore structure varies with habitat: in similar habitats, S. annulatum tends to show the most numerous/smallest pores, S. jensenii intermediate, and S. majus the fewest/largest; some subsp. majus plants can approach S. annulatum on convex-surface pore size/number but not on concave-surface pores, where S. majus remains nearly poreless.¹

Microscopy (when macromorphology overlaps)

In doubtful cases, microscopy is emphasized; for S. annulatum, S. jensenii, S. balticum, and S. majus, use combinations rather than a single character in isolation.¹ Pore traits can vary with habitat and (in some cases) sex; interpret them as a combination of characters rather than relying on a single pore count or pore type in isolation.¹

1. Compare the relative length of hyalocystsLarge, empty, transparent leaf cells in Sphagnum, specialized for water storage; also called hyaline cells or leucocysts in divergent branch leaves: markedly longer hyalocysts in the basal part than in the middle part supports S. jensenii; more uniform hyalocyst length supports S. annulatum.¹

2. Stem cortexouter layer or layers of stem or branch, consisting of comparatively large, thin-walled cells

   differentiation in cross sectioncut made to an organ to show the internal structure

   S. annulatum is characterized by an undifferentiated or poorly differentiated cortex, whereas S. jensenii and S. majus are described as having more clearly differentiated cortical cells.¹

3. On the convex surface of divergent branch leaves: commissural pseudoporesThin or partially resorbed spot in a hyaline cell wall that resembles a pore but is not fully perforated; also called an imperfect pore by some authors. are described as rare in S. annulatum but common in S. jensenii; ringed porespore surrounded by a ring of thickened cell wall are described as more commonly occurring in S. annulatum than in S. jensenii and S. majus.¹
4. On the concave surface of divergent branch leaves: many pores are described for S. annulatum and S. jensenii compared with S. majus, where pores are described as lacking or nearly so in typical material. Contrary to many reports, S. majus can show pores on the concave surface of divergent branch leaves, but these are commissural rather than free pores.¹
5. In S. jensenii vs S. balticum comparisons, S. balticum usually shows fewer hyalocystLarge, empty, transparent leaf cells in Sphagnum, specialized for water storage; also called hyaline cells or leucocysts pores on the convex surfaceabaxial surface (of a leaf) of divergent branch leaves.

Images (examples) { .collapse }

Lookalike Sources

1. FLATBERG, K. I. (1988). Taxonomy of Sphagnum annulatum and related species. Annales Botanici Fennici, 25(4), 303–350. https://www.jstor.org/stable/23725638
2. FLATBERG, K. I. (2015). Pisktorvmose Sphagnum annulatum H.Lindb. ex Warnst. [English gloss: fishbone peatmoss]. Artsdatabanken ("Forvekslingsarter" [English: lookalike species] section). https://artsdatabanken.no/arter/takson/188573/beskrivelse. Retrieved [17/02/2026]
3. FLATBERG, K. I. (2015). Flarktorvmose Sphagnum jensenii [English gloss: flark peatmoss]. Artsdatabanken ("Forvekslingsarter" [English: lookalike species] section). https://artsdatabanken.no/arter/takson/188736/beskrivelse. Retrieved [17/02/2026]
4. FLATBERG, K. I. (2015). Svelttorvmose Sphagnum balticum [English gloss: slender peatmoss]. Artsdatabanken ("Forvekslingsarter" [English: lookalike species] section). https://artsdatabanken.no/arter/takson/188762/beskrivelse. Retrieved [17/02/2026]
5. FLATBERG, K. I. (2015). Lurvtorvmose Sphagnum majus subsp. majus [English gloss: shaggy peatmoss]. Artsdatabanken ("Forvekslingsarter" [English: lookalike species] section). https://artsdatabanken.no/arter/takson/64965/beskrivelse. Retrieved [17/02/2026]

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Sources: Text & Images

Sources used in the description of the sphagnum. Pictures are taken by me unless a source is mentioned.

1. FLATBERG, K. I. (1988). Taxonomy of Sphagnum annulatum and related species. Annales Botanici Fennici, 25(4), 303–350. https://www.jstor.org/stable/23725638
2. FLATBERG, K. I. (2015). Pisktorvmose Sphagnum annulatum H.Lindb. ex Warnst. NTNU Vitenskapsmuseet. https://artsdatabanken.no/arter/takson/188573/beskrivelse. Retrieved [16/09/2025]
3. AYOTTE, G., & ROCHEFORT, L. (2020). Sphagnum Mosses of Eastern Canada. Éditions JFD.
4. SLU ARTDATABANKEN (2026). Artfakta: krusvitmossa (Sphagnum annulatum). SLU Artdatabanken. https://artfakta.se/taxa/2883. Retrieved [05/02/2026]
5. FLATBERG, K. I. (2002). The Norwegian Sphagna: a field colour guide. Norges teknisk-naturvitenskapelige universitet. https://hdl.handle.net/11250/271981.

Additional Images taken by yours truely { .collapse }

↑ Can be found with brown mosses (high nutrient demand)

↑ Can be reddish-brown

↑ Can be pretty sizable. Often S. lindbergii (middle left, and middle bottom of the image) is one of the largest European sphagnum.

↑ Can be found in wide mats

↑ See blue arrows

↑ Can be medium sized and slightly wild looking, but still has fairly straight capitulum branches when viewed from above. Also notice the long and slender stem leaves sticking out from the stem.

↑ Still has fairly straight capitulum branches when viewed from above.

↑ Also notice the long and slender stem leaves sticking out from the stem.

↑ Can have pores in one row instead of two as well

↑ More commonly pores in two rows instead of one

↑ Often has tiny ringed pores in the tip of the stem leaves

↑ Common pore structure on concave side of branch leaf

↑ Can sometimes have big and weirdly (not displayed in this image) shaped pores on the bottom, and sometimes throughout the branch leaves

↑ More likely than not a good bit longer than wide stem leaf

↑ Stem cortex not developed

↑ Stem cortex slightly (1-2 rows) developed

↑ Common branch leaf shape

↑ Branch leaf cells of similar size from the bottom to the middle of the leaf

↑ Branch leaf cells of similar size from the bottom to the middle of the leaf

↑ Branch leaf cells of similar size from the bottom to the middle of the leaf

↑ Branch leaf cells of similar size from the bottom to the middle of the leaf

Sphagnum added so far:

S. annulatum

Additional external resources:

Sphagnum structure and ecology
Conducting tissues and phyletic relationships of bryophytes