BFNA Title: Orthothecium
Author: P. L. Redfearn, Jr. 
Date: February 10, 2005
Edit Level: 1 Brum+
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden
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 Hypnaceae - Orthothecium


XX. ORTHOTHECIUM Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryo. Eur. 5: 105 (fasc. 48. Monogr. 1.) 1852, conserved name * [ortho, erect, and thecium, capsule].


              Paul L. Redfearn, Jr.


Holmgrenia Lindburg. Öfers. Förhandl, Kongl. Svenska Vetensk.-Akad. 19: 605. 1863


Plants very small to robust, in loose to dense, soft, shiny, green, yellowish, golden, or reddish tufts.  Stems erect, ± straight to distinctly secund, not to sparsely branched, pseudoparaphyllia lacking, epidermal cells in 3--4 rows of small, very thick-walled cells surrounding a zone of larger, thinner-walled cells, and a central strand composed of very thin-walled cells; branches radiculose at base. Stem and branch leaves similar, erect to erect-spreading, lanceolate to ovate, acuminate, ± concave, plane to strongly plicate; margins incurved from base to middle, plane or recurved above, acumen entire or minutely serrulate; costa lacking or short and double to reaching the middle of the leaf, one fork usually longer than the other; costa cells similar to leaf cells but thick-walled and porose; distal leaf cells linear, ± flexuose, smooth, usually somewhat incrassate and porose throughout, but conspicuously so in proximal portion of leaf; alar cells not differentiated, cells across insertion often darker,  relatively short and thick-walled. Specialized asexual reproduction very rare, by axillary propagula. Sexual condition dioicous.  Perigonia and perichaetia near base of stem, perichaetial leaves lanceolate, ovate-lanceolate to ovate-triangular, acuminate, margins plane, serrulate to sharply serrate, distally, ecostate, cells linear, thick-walled, porose. Seta elongate, golden brown, purple or reddish, twisted. Capsule erect and symmetric to slightly asymmetric, cylindric to subglobose, commonly flaring at mouth; operculum conic; exothecial cells ± isodiametric to rounded; stomata few at extreme base of urn; annulus composed of 2--3 rows of ± thick-walled cells; peristome double, attached at the mouth, exostome teeth broadly lanceolate, bordered, pale yellow, papillose distally, cross-striolate proximally, segments keeled and perforate, front surface with a zig-zag center line; basal membrane of endostome low to moderately high, basal segments broad to linear, usually papillose, keeled and perforate, as long as exostome to somewhat longer, cilia present or lacking.  Calyptra cucullate, smooth and naked.  Spores 10--16 µm.


Species 10 (5 in the flora); terrestrial, calcicolous habitats from near sea level to high elevations in temperate to boreal and Arctic regions; North America, Europe, Asia, Africa.


Many authors (V. F. Brotherus 1907; E. Lawton 1971; A. Noguchi 1990; E. Nyholm 1965) have placed Orthothecium in the Entodontaceae. However, W. R. Buck (1980) concluded that Orthothecium, based on leaves with a short, double costa, undifferentiated alar cells and a hypnoid peristome, should be placed in the Hypnoideae of the Hypnaceae


SELECTED REFERENCES: Brotherus, V. F. 1907. Entodontaceae. In: A. Engler & K. Prantl, eds., Die naturlichen Pflanzenfamlien, 1(3): 870--899. Leipzig.  Buck, W. R. 1980. A generic revision of Entodontaceae. Jour. Hattori Bot. Lab. 48: 147--150.  Lawton, E. 1971.  Moss Flora of the Pacific Northwest. Miyazaki, Japan.  Noguchi, A. 1994. Illustrated Moss Flora of Japan. Part 5 Miyazaki, Japan. Nyholm, E. 1965. Illustrated Moss Flora of Fennoscandia II. Fasc. 5, 565--570.


1. Leaves distinctly plicate; stems ca. 3 mm wide and up to 10 cm long.

2.      Plants reddish to brownish green; leaves somewhat secund, with long, slender acuminate points, not decurrent,  margins plane. . . . .. 2. Orthothecium  rufescens   

2.      Plants golden; leaves with short-acuminate points, slightly decurrent, margins partially  recurved . . . . . .. . . . . 1. Orthothecium chryseum

1. Leaves not or only slightly plicate, less than 0.5 mm wide and up to 4 cm long.  

3. Leaves homomallous, narrow, long-acuminate, margins plane to somewhat

    revolute. . . . . . . . . . . . . . . . . . . . . . 3.  Orthothecium intricatum

3. Leaves straight, ovate- to ovate-lanceolate.

            4. Leaf margins partially recurved, ovate-lanceolate, ending in short, flexuose, subhyaline acumination  . . . . . . . . . . . . . .  4. Orthothecium strictum

4. Leaf margins plane, broadly ovate, abruptly short-acuminate to

   apiculate . .  . . . . . . . . . . . . . . . . . . . . . . . . 5. Orthothecium acuminatum


1. Orthothecium chryseum (Schwägrichen) Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryo. Eur. 5: 107 (fas. 48. Monogr. 3). 1851.


Plants robust, golden, forming turf. Stems ca. 3 mm wide and 5--10 cm long, erect or ascending, simple or sparingly branched. Leaves imbricate, ovate-lanceolate to ovate-triangular, short-acuminate, 1--5 mm, concave, or cochleariform, strongly plicate, slightly decurrent, margins partially recurved, entire; median leaf cells linear, ca. 84 × 6 µm; basal cells shorter and broader, thick-walled and incrassate, golden brown; costa absent or very short and double. Specialized asexual reproduction absent. Sporophytes infrequent. Perichaetial leaves ovate-triangular, interior long-acuminate, sharply toothed above, not plicate. Seta golden brown, 2--3 cm.  Capsule ovoid-cylindric, frequently slightly asymmetric, 1.5--1.8 mm, contracted  below mouth when dry and empty; annulus composed of 2 rows of cells; cilia short. Spores 14--16 µm.


1. Leaves concave .  .  . . . . . . . . . . . . . . .1a. Orthothecium chryseum var. chryseum

1. Leaves cochleariform . . . .  . . . .1b. Orthothecium chryseum var. cochlearifolium


1a. Orthothecium chryseum var. chryseum


Leaves concave.


Rarely producing sporophytes.  Moist calcareous rock ledges, faces & crevices, in depressions, along edges of streams, humus, seepage areas of talus slopes, ice wedge polygons, hummocks, dung, alpine and arctic tundra; 0--3900 m (Colorado); Greenland; Alta., B. C., Labrador, Man., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo. Mont.; n & c Europe; Atlantic Islands (Iceland); Arctic Asia (Russia).


1b. Orthothecium chryseum var. cochlearifolium (Lindberg) Limpricht, Laubm. Deutschl. Oesterr. Schweiz 3: 23. 1895


Leaves cochleariform.


Sporophytes unknown. Moist calcareous area of Arctic tundra; near sea level to 1100 m; Nunavut; Greenland (?).


Orthothecium chryseum is characterized by robust stems ca. 3 mm wide and over 4 cm long, and its distinctly golden, plicate leaves with short-acuminate points. It is by far the most common Orthothecium in North America. The var. cochlearifolium is known from a few localities in Nunavut. It is distinguished by distinctly cochleariform leaves.


2. Orthothecium rufescens (Bridel) Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryo. Eur. 5: 107, 480 (fasc. 48 Mon. 1: 3) 1851


Hypnum rufescens  Bridel, Muscologia 2(2): 139. 1801


Plants reddish  to brownish green, in robust, slightly glossy mats. Stems ca. 3 mm wide and 4--10 cm long, sparingly branched. Leaves ± appressed when dry, erect-spreading when moist, linear-lanceolate, with long, slenderly acuminate points, 3 mm, caniculate-concave, strongly plicate, not decurrent, margins plane, entire, costa absent; median and distal cells linear. 65--85 × 4--5 µm; proximal cells shorter, 20--40 µm, walls porose. Specialized asexual reproduction absent.  [Seta purple, erect. Capsule erect, operculum obliquely conic-rostrate. Spores ca. 16 µm.]


Moist tundra, on soil, granite, limestone, schist, 2--1645 m. Greenland; N.W.T., Nunavut, Yukon; Alaska; Europe; Asia (Siberia, Japan).


Plants of Orthothecium rufescens, like those of O. chryseum, are large and robust with distinctly plicate leaves, but can be distinguished from this species by the reddish color and slenderly acuminate leaves.


3. Orthothecium intricatum (Hartman) Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryo. Eur. fasc., vol. 5, 457. 1851


Leskea intricata Hartman, Skand. Fl. Ed 5: 336. 1849


Plants slender, in dense green to yellow-green mats or tufts. Stems 0.2--0.3 mm wide and up to 4 cm long, slender, yellow-brown, curved--ascending, sometimes creeping   Leaves erect to erect-spreading, narrowly lanceolate, gradually subulate, homomallous, 1--1.8 mm occasionally ± twisted-flexuose when dry, smooth or faintly striolate, margins plane to somewhat revolute, entire or somewhat sinuate, costa absent or very short and double, cells elongate, linear, ± porose, 45--75 × 4--6 µm; basal cells shorter, broader, often yellow, incrassate, porose. Specialized asexual reproduction rare, by short, filamentous propagula in axils of leaves. Seta red-brown,1.5 -- 2 cm. Capsule erect and symmetric, 1.5 --2 mm; endostome low, segments somewhat longer than teeth, cilia lacking. Spores 10--14 µm.


Rarely producing sporophytes. Moist shaded calcareous soil, granite, schist, limestone, rock ledges and vertical cliff faces, tundra, 200--1500 m. Greenland; B. C., N.W.T., Nunavut, Ont.?, Que., Yukon; Alaska; n. Eurasia, China, Japan.


Orthothecium intricatum is distinguished by leaves that are homomallous, and narrowly lanceolate with plane to slightly revolute margins.


3. Orthothecium strictum Lorentz, Moosstudien 122. 5d. 1864


Orthothecium binervulum Molendo, Moostudien 120. 1864


Plants small, in orange, glossy tufts. Stems ca.0. 5 mm wide and 1--6 cm long, erect to ascending, sparingly branched. Leaves erect-imbricate, ovate-lanceolate, ending in a short, flexuose, subhyaline acumination, ± 1 mm, not to only slightly plicate, margins partially recurved, serrulate distally, costa short and double; median leaf cells oblong-linear, 48--64 × 8 µm; proximal basal cells shorter, brownish yellow; alar cells poorly differentiated. Specialized asexual reproduction rare, by clusters of claviform, multicellular propagula in axils of leaves. Perichaetial leaves ovate-lanceolate. Sporophytes apparently very rare, not seen.


Moist tundra, humus, soil, rock ledges, crevices, 10 to 2800 m. Alta, B. C., Man., Nfld., N.S., N.W.T., Nunavat, Yukon, Que.; Alaska, Colo.; Europe


Orthothecium strictum is distinguished by stems up to 0.5 mm wide and 1--6 cm long, and the indistinctly plicate, erect-imbricate, narrowly lanceolate leaves with revolute margins, ending in a short, flexuose, subhyaline acumination. A single collection (Alaska, Steere 18846, NY) had claviform multicellular propagula present in axils of leaves.


5. Orthothecium acuminatum Bryhn, Rep. Second Norw. Arctic Exped. Fram 1898--1902 2 (11): 126 1 f. 4. 1907


Plants in very small tufts, golden--green distally, brownish proximally. Stems 0.5 mm wide and up to 3--4 cm long, sparsely branched, often with slender stoloniferous branches bearing minute leaves. Leaves closely appressed--imbricate, margins plane, broadly ovate, abruptly very short-acuminate to apiculate, 0.6--0.8 mm, slightly serrate above; median leaf cells oblong to oblong-rhombic, ca. 35--40 × 9 µm; basal cell shorter, incrassate and deeply colored, obscure; alar cells scarcely differentiated; costa lacking. Specialized asexual reproduction absent.  Sporophytes unknown.


Wet calcareous habitats, arctic tundra; Greenland; N.W.T., Nunavut; Alaska.


Orthothecium acuminatum is distinguished by narrow stems 0.5 mm wide and up to 4 cm long, with straight, broadly ovate, abruptly short-acuminate to apiculate leaves. It is known in North America only from a few localities in the Northwest Territories and one locality in Alaska. William Weber (personal communication to R. R. Ireland) suggested that O. diminutivum (Grout) H. A. Crum & L. E. Anderson, described from Colorado, is synonymous with Isopterygiopsis puchella (Hedwig) Z. Iwatsuki. R. R. Ireland (2003) accepted this suggestion.




Ireland, R. R. 2003. Isopterygiopsis. Bryophyte Flora of North America, Provisional Publication, Version 2. BFNA Web Site, Missouri Botanical Garden