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BFNA | Family List | BFNA Vol. 1 | Sphagnaceae

Sphagnum Linnaeus, Sp. Pl. 1106. 1753. * [From the Greek for an unknown plant].

Authors: Richard E. Andrus

Plants typically with upright stems, young branches arranged spirally around stem at growing apex into a capitulum, branches clustered into fascicles along stem, stem and branch leaves of alternating inflated, S-shaped to rhomboidal hyaline cells and narrow linear chlorophyllous cells, hyaline cells typically fibrillose and porose on branch leaves. Stems differentiated into a central cylinder of thin-walled parenchymatous cells, merging into a cylinder of thick-walled cortical cells surrounded by 0--4 layers of thin-walled inflated cells, superficial layer of cells usually aporose, but may be porose. Stem leaves may be less fibrillose or efibrillose and less porose or aporose compared to branch leaves, often septate, a distinct border of narrow linear chlorophyllous cells often along margins and at base, and with a greater width:length ratio than branch leaves in anisophyllous forms, partly differentiated in hemiisophyllous forms, and identical in isophyllous forms. Branches typically dimorphic as spreading and pendent branches, but some species lack branches or branches are not clearly differentiated, pendent branches typically more slender than spreading branches and with a tendency to adhere to and cover the stem. Branch fascicles typically with 2 spreading and 1--2 pendent branches, but there may be to 12(14) per fascicle. Branch stems typically green, with a superficial layer of inflated retort cells; these grouped or solitary, usually porose at the distal end with a conspicuous or inconspicuous neck. Branch leaves with 2/5 phyllotaxy, of a 1-stratose network of alternating chlorophyllous and hyaline cells; hyaline cells usually S-shaped, rarely rhomboidal, nearly always strengthened with conspicuous spiral fibrils, small to large round to elliptic and sometimes ringed pores occur along commissures or rarely on cell lumen, convex surface typically with more pores per cell than concave surface; chlorophyllous cells may be enclosed on both surfaces, more broadly exposed on one surface or equally exposed on both surfaces as viewed in transverse section, adjacent cell walls typically smooth, but various types of cell wall projections may be clearly visible in transverse section. Sexual condition dioicous or monoicous, stalked globose antheridia borne at the tips of branches usually with swollen colored tips of branches near capitulum, long-necked archegonia borne on short branches singly surrounded by perichaetial leaves that are typically longer than branch leaves. Sporophyte a spherical capsule with pseudostomata on capsule surface, a very short seta, and a foot, exserted on a pseudopodium of gametophyte tissue. Capsule spherical, brown to black, lacking an annulus or peristome with a operculum convex; calyptra membranous; spore sac amphithecial in origin, over arching columella. Spores tetrahedral, with prominent trilete mark, fine to coarse superficial surface, distal surface may have raised Y-mark, bifurcated Y-mark sculpture, or none. Protonema thallose, typically 1-stratose, gametophyte developing from lateral margin.

Species 250 (88 in the flora); primarily in boreal regions$ but also in cool, moist montane and oceanic habitats such as nutrient poor and acidic wetlands and mires; worldwide in distribution, except for Antarctica.

The concept of species in the genus is controversial. We have followed the lead of P. Isoviita (1966) and K. I. Flatberg (1994) in the recognition of species. H. A. Crum (1984) and others (R. E. Daniels and A. Eddy 1985; A. L. Andrews 1958, 1959) have adopted more conservative taxonomic species concepts for species in the Northern Hemisphere. Discussion of the spores above is from T. Cao and D. H. Vitt (1986); for additional discussion of the protonema see C. McQueen (1988).

Microscopic features can be observed by using a concentrated aqueous or alcohol solution of Crystal Violet. A 50% solution of alcohol and Methylene Blue or Safranin Red can be used, but these usually do not stain features such as minute pores, fibrils, wall thinnings, and surface sculpture on the chlorophyllous cells. The number and kinds of branches should be determined, individual stem and branch leaves (from the middle of a spreading branch) should be examined from the distal 2 cm of the plant, and the superficial surface of stem cortical cells may need examination as well as cross sections of branch leaves and stems.


Andrus, R. E. 1980. Sphagnaceae (Peat Moss Family) of New York State. New York State Mus. Bull. 442.
Crum, H. A. 1984. Sphagnopsida, Sphagnaceae. North American flora, Series II, Part 11. New York Botanical Garden, Bronx, New York.
Daniels, R. E. and A. Eddy. 1990. Handbook of European Sphagna. Institute of Terrestrial Ecology, Huntingdon.
Flatberg, K. I. 2002. The Norwegian Sphagna: A field colour guide. NTNU Vitenskapsmuseet Rapp. Bot. Ser. 2002-1: 1--44 + 54 plates.
Isoviita, P. 1966. Studies on Sphagnum L. 1. Nomenclatural revision of the European taxa. Ann. Bot. Fennici 3: 199--264.
McQueen, C. B. 1990. Field Guide to the peat mosses of Boreal North America. London.
Nyholm, E. 1969. Illustrated moss flora of Fennoscandia II. Musci 6: 647--799. Lund.


Andrews, A. L. 1958. Notes on American Sphagnum. X. Review. Bryologist 61: 269--276.
Andrews, A. L. 1959. Notes on North American Sphagnum. Sphagnum subsecundum. Bryologist 62: 87--96.
Andrews, A. L. 1960. Notes on North American Sphagnum. XII. Sphagnum cyclophyllum. Bryologist 63: 229--234.
Andrus, R. E. 1979. Sphagnum subtile (Russow) Warnst. and allied species in North America. Syst. Bot. 4: 351--362.
Andrus, R. E. 1980. Sphagnaceae (peat moss family) of New York State. N.Y. State Mus. Bull. 442. Albany, NY.
Andrus, R.E. 1987. Nomenclatural changes in Sphagnum imbricatum sensu lato. Bryologist 90: 217--220.
Bryan, V. 1955. Chromosome studies in the genus Sphagnum. Bryologist 58: 16--39.
Cao, T. & D. H. Vitt. 1986. Spore surface structure of Sphagnum. Nova Hedwigia 43: 191--220.
Cronberg, N. 1997. Genotypic differentiation between the two related peat mosses, Sphagnum rubellum and S. capillifolium in northern Europe. J. Bryology 19: 715--729.
Cronberg, N. 1998. Population structure and interspecific differentiation of the peat moss sister species Sphagnum rubellum and S. capillifolium (Sphagnaceae) in northern Europe. Plant Syst. Evol. 102: 589--614.
Crum, H. 1984. Sphagnopsida. Sphagnaceae. North American Flora. Series II, Part II. The New York Botanical Garden. Bronx, New York. Crum, H. 1997. A seasoned view of North American Sphagna. J. Hattori Bot. Lab. 82: 77--98.
Daniels, R. E. & A. Eddy. 1985. Handbook of European Sphagna. Institute of Terrestrial Ecology. Huntingdon, England.
Flatberg, K. I. 1984. A taxonomic revision of the Sphagnum imbricatum complex. K. Norske Vidensk. Selsk. Skr. 3: 1--80. Flatberg, K. I. 1985. Studies in Sphagnum subfulvum Sjörs, and related morphotypes. Lindbergia 11: 38--54.
Flatberg, K. I. 1987. Taxonomy of Sphagnum majus (Russ.) C. Jens. K. Norske Vidensk. Selsk. Skr. 2: 1--42.
Flatberg, K. I. 1988. Sphagnum viridum sp. nov., and its relation to S. cuspidatum. K. norske Vidensk. Selsk. Skr. 1: 1--63.
Flatberg, K. I. 1989. Sphagnum (Cuspidata) pacificum, sp. nov. Bryologist 92: 116--119.
Flatberg, K. I. 1992. The European taxa in the Sphagnum recurvum complex. 1. Sphagnum isoviitae sp. nov. J. Bryology 17: 1--13.
Flatberg, K. I. 1993. Sphagnum rubiginosum (Sect. Acutifolia), sp. nov. Lindbergia 18: 59--70.
Flatberg, K. I. 1994. Norwegian Sphagna. A field colour guide. Universitetet I Trondheim, Vitenskapsmusseet Rapport Botanisk Serie 1994--3. Trondheim, Norway.
McQueen, C. B. 1985. Spore morphology of four species of Sphagnum in section Acutifolia. Bryologist 88: 1--4.
McQueen, C. B. 1988. Growth and development of Sphagnum subtile protonemata. Evansia 5: 17--21.
McQueen, C. B. 1989. A biosystematic study of Sphagnum capillifolium sensu lato. Bryologist 92: 1--24.

1 Outer stem cortical cell walls reinforced with spiral fibrils.   1a Sphagnum sect. Sphagnum
+ Outer stem cortical cell walls smooth.   (2)
2 (1) Outer cortical cells of branches nearly all porose at distal end; branch leaves with denticulate margins and bordered with resorption furrow.   Sphagnum sect. Rigida
+ Outer cortical cells of branches of two kinds, smaller aporose cells and larger retort-shaped cells with pore at apical end; branch leaf margins usually entire.   (3)
3 (2) Fascicles of 7 or more branches.   Sphagnum sect. Polyclada
+ Fascicles of 6 or fewer branches.   (4)
4 (3) Branch leaf hyaline cells efibrillose.   Sphagnum sect. Isocladus
+ Branch leaf hyaline cells fibrillose.   (5)
5 (4) Branch and stem leaves isophyllous; branches in fascicles of 2--3, spreading and pendent branches similar, or plants may have single or no branches; hyaline cells of branch leaves usually with numerous pores along the commissures, giving a bead-like appearance; chlorophyllous cells of branch leaves in transverse section barrel-shaped, truncate-elliptic to trapezoidal, exposed equally on both surfaces or slightly more broader on the convex surface.   Sphagnum sect. Subsecunda
+ Branch and stem leaves usually anisophyllous; 3--6 branches per fascicle, spreading branches clearly differentiated from pendent branches; hyaline cells of branch leaves with scattered pores along the commissures; chlorophyllous cells of branch leaves in transverse section triangular, truncate-trapezoidal to elliptical and may be more broadly exposed on the either surface.   (6)
6 (5) Branch leaf chlorophyllous cells triangular to trapezoidal, exposed much more broadly on concave or convex surface.   (7)
+ Branch leaf chlorophyllous cells lenticular, truncate-elliptic to trapezoidal; exposed more or less equally on both surfaces or slightly more broadly on convex surface.   (8)
7 (6) Chlorophyllous cells of branch leaves triangular to trapezoidal in transverse section, more broadly exposed on the concave surface; in plants with stellate capitula, the branches between the rays of the capitulum single; stem leaves upright on the stem.   Sphagnum sect. Acutifolia
+ Chlorophyllous cells of branch leaves triangular to trapezoidal in transverse section, more broadly exposed on the convex surface; in plants with stellate capitula, the branches between the rays of the capitulum occur in pairs; stem leaves often hanging downward on the stem.   Sphagnum sect. Cuspidata
8 (6) Stem leaves with apex broad and fimbriate; branch leaves often squarrose from an enlarged clasping base; interior surface of chlorophyllous cells often finely papillose.   Sphagnum sect. Squarrosa
+ Stem leaves with apex obtuse and entire to erose; branch leaves straight, slightly subsecund, or slightly recurved; interior surface of chlorophyllous cells always smooth.   (9)
9 (8) Branch leaves with broad truncate toothed apex,hyaline cells with pores in cell ends and angles.   Sphagnum sect. Insulosa
+ Branch leaves with rounded, untoothed or weakly toothed apex, hyaline cells on convex surface with numerous pores along commissures.   Sphagnum sect. Subsecunda

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