BFNA Title: Tomentypnum
Author: J. Faubert 
Date: September 8, 2004
Edit Level: R

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

BFNA Web site:


Return to Home

Amblystegiaceae -- Tomentypnum


XXX. TOMENTYPNUM Loeske, Deutsch. Bot. Monatsschr. 22 : 82. 1911 * [Latin, tomentosus felty, refering to the felted rhizoids, and Greek, hypnos, sleep, in antiquity applied to various mosses or lichens]   

Jean Faubert

Camptothecium sect. Tomentella Kindberg, Eur. N. Amer. Bryin. 1 :86. 1897; Homalothecium subgen. Tomentypnum (Loeske) H. Robinson [as "Tomenthypnum"]


Plants robust, erect, forming loose to dense turfs or hummocks, golden to yellow-green or golden-brown, glossy when dry. Stems  (4--)5--9(--13) cm; pinnately or subpinnately branched in one plane, branches horizontal, straight to arcuate; epidermis of small and thick-walled cells, central strand present, cells of inner cortex thin-walled; paraphyllia absent, pseudoparaphyllia foliose; rhizoids smooth, sometimes warty-papillose at base, abundant (sometimes reduced or absent) much branched, reddish brown forming a conspicuously tomentum over the entire length of one side of the stem; rhizoids or rhizoid initials on stem and abaxially on costa, smooth, strongly branched (often forming tomentum); axillary hairs 2--5(--6)-celled. Stem leaves crowded, erect to erect-spreading, straight or falcate-secund, little changed when wet, long-lanceolate, slenderly acuminate, non-decurrent, strongly plicate, (2--)2.5--4 mm; margins plane or narrowly and tightly recurved, entire or sinuose; costa single, ending near the leaf apex; laminal cells long-linear to vermicular, cell walls incrassate, nodose, becoming porose in proximal parts of leaves; one or two rows of shorter and sometimes colored cells at insertion; alar cells not or scarcely different from other cells at leaf insertion. Branch leaves smaller but otherwise little different from stem leaves. Specialized asexual reproduction not seen.  Sexual condition dioicous, often sterile; perichaetial leaves long-lance-subulate, to 7 mm, strongly plicate, margin entire, costa single and ending far beyond mid leaf; paraphyses present on vaginula. Seta 2.5--4.5(--5) cm, smooth, straight to somewhat flexuose, slightly twisted when dry, reddish brown, darker below, lighter above. Capsule inclined to horizontal, smooth, oblong-cylindric, arcuate, contracted below mouth when dry, neck short, wrinkled when dry; stomates few, long-pored; annulus separating, of 3--4 rows of cells; operculum conic to long-conic, apiculate; peristome perfect; exostome teeth lanceolate, basally reticulate, distally papillose, bordered and trabeculate, brownish yellow; endostome with high basal membrane, segments narrowly split along midlines, cilia 2--3(--4), well developed, nodulose. Calyptra cucullate, naked. Spores 12--18 µm, granulose to minutely papillose.


Species 2 (2 in the flora): widely distributed in the Holarctic.


The major characters of Tomentypnum are the erect habit, thick rhizoidal tomentum on one side of stem, presence of rhizoids on the proximal abaxial surface of the costa, strongly pluriplicate leaves, absence of clearly differentiated alar cells, and the presence of a stem central strand that can vary from sharply defined to barely discernible on the same stem. However, in Arctic-alpine environments, plants of both species will be found without tomentum or with reduced tomentum. These plants were at times described as varieties of T. nitens but are now considered phenotypes of harsh environments. Contrariwise, plants with tomentum around the whole circumference of the stems are sometimes encountered. Shape of the leaves is the major character separating the two species. As pointed out by R. Gauthier (1987), some variability in the curvature of the leaves is occasionally present on some plants but atypical leaves are usually localized to a few branches or to a sector of the stem. There is little difference in size of leaves or stems that can be used to separate the two species. Sporophytes are uncommon. An invalid orthographical variant ("Tomenthypnum") is widely used in North America. The spelling retained here is Loeske’s original. Tomentypnum occurs from lowlands to alpine summits, in swampy grounds, wetlands, and peatlands. The habitat preferences of the two species, although quite distinct, do overlap to some extent as suggested by the existence of a number of intermixed populations, usually from moderately rich fen habitats (D. H. Vitt and C. D. Hamilton 1975; R. Gauthier 1987). One species, T. nitens, is very common in boreal and Arctic-alpine areas of North America.


SELECTED REFERENCES  Vitt, D. H. and C. D. Hamilton. 1975. Taxonomic Status of Tomenthypnum falcifolium. Bryologist 78: 168--177.  Vitt, D. H., T. Cao, M. K. Campenot and R. Gauthier. 1990. The genus Tomentypnum in north-east China. J. Bryol. 16 :79--87.


1. Leaves falcate-secund, often twisted in their distal portions, widest just above the base; rhizoid initials restricted to proximal portion of stem leaves, stems smooth; usually in Sphagnum-dominated vegetation . . . . 1. Tomentypnum falcifolium

1. Leaves straight, not or little twisted in their distal portions, widest at base; rhizoids initials on proximal portion of stem leaves and on stems just below leaf insertions; rich fens . . . . 2. Tomentypnum nitens


1. Tomentypnum falcifolium (Nichols) Tuomikoski in Ahti & Fagerstén, Ann. Bot. Fenn. 4 : 435. 1967


Camptothecium nitens var. falcifolium Nichols, Rhodora 15 :12, 1913; Homalothecium nitens var. falcifolium (Nichols) Wijk & Margadant; Tomentypnum nitens var. falcifolium (Nichols) Podpěra


Stems smooth, rhizoids restricted to the proximal part of stem leaf costa. Leaves falcate-secund, distal portions often twisted, narrowly ovate-lanceolate, gradually narrowed to slender acuminate apex, widest above base, slightly narrowed to insertion.


Capsules mature early to mid summer. Acidic, oligotrophic environments, often associated with Sphagnum species on hummocks and turfs; Greenland; Alta., B.C., Man., N.B., Nfld. & Labr., N.W.T., N.S., Nunavut, Ont., Que., Sask., Conn., Maine, Mich., Minn., N.Y.; Asia (China, Siberia).


The shape of the leaf base is best observed while the leaves remain attached to the stem. Tomentypnum falcifolium is widespread but more sporadic than T. nitens, occurring across the boreal and sub-Arctic areas of Canada, extending south into the northeastern United States.


2. Tomentypnum nitens (Hedwig) Loeske, Deutsch. Bot. Monatsschr. 22: 82. 1911


Hypnum nitens Hedwig, Sp. Musc. Frond. 255. 1801; Camptothecium nitens (Hedwig) Schimper; Homalothecium nitens (Hedwig) H. Robinson; Tomentypnum nitens var. involutum (Limpricht) C. E. O. Jensen


Stems with rhizoides in 1(--2) transverse rows just below leaf inservations, rhizoids also occurring abaxially on the proximal portions of stem leaf costa. Leaves erect to erect-spreading, straight, tapering from the bases to a long-acuminate apex.


Capsules mature early to mid summer. Forming turfs and hummocks in calcareous to intermediately mineral-rich, mesotrophic in association with other calciphiles, usually found with mosses such as Paludella squarrosa and species of Aulacomnium; Greenland; St..Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. & Labr., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Conn., Idaho, Ill., Maine, Mass., Mich., Minn., Mont., N.H., N.J., N.Mex., N.Y., N.Dak., Ohio, Oreg., Pa., Utah., Vt., Wash., W.Va., Wis., Wyo.; n and c Europe; n Asia; Atlantic Islands (Iceland); Pacific Islands (Aleutian Islands).


Common and widespread across boreal and arctic areas of the Northern Hemisphere, reaching the high Arctic and extending south to New Mexico in high mountains. In Arctic-alpine conditions a form is often encountered characterized by stem without rhizoids, leaves closely appressed, branches straight, erect and close to the stem.




Gauthier R. 1987. La répartition et l’habitat du Tomenthypnum falcifolium au Québec-Labrador. Can. J. Bot. 65 :286--298.