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BFNA | Family List | BFNA Vol. 1 | Dicranaceae

Dicranum Hedwig, Spec. Musc. 126. 1801.

Greek dicranon, pitchfork

Robert R. Ireland

Plants in loose to dense tufts, yellowish green to dark green, dull or shiny. Stems (0.5--)2--12(--18) cm, erect, simple or forked, densely tomentose with white or reddish brown, smooth to papillose rhizoids, these sometimes nearly lacking, rhizoids arising at bases of branches (macronemata) and sometimes in rows scattered along stems (micronemata). Leaves usually lanceolate, rarely ovate, proximal part concave, rarely flat, distal subula keeled to tubulose, erect-appressed, erect-patent or spreading, straight, weakly curled, crispate or cirrate when dry, generally falcate-secund, less often straight, undulate, rugose or smooth; apices acute to obtuse, tips sometimes deciduous, apparently a means of asexual reproduction; margins plane to incurved or involute, entire to serrate in distal part, entire below; laminae 1- or 2-stratose at margins or sometimes near costa; costa single, ending below apex to excurrent, smooth or toothed on abaxial surface, sometimes with 2--4 serrated ridges abaxially, 1--2 rows of guide cells, two well-developed stereid bands above and below, sometimes slightly differentiated or lacking, extending to apex, or ending below, adaxial and (or) abaxial epidermal layers of cells differentiated or undifferentiated, sometimes only a few cells in both layers enlarged; laminal cell walls weakly to strongly bulging, or bulges lacking; leaf cells pitted or nonpitted, smooth or sometimes abaxially, rarely adaxially, mammillose, papillose or toothed by projecting cell ends, walls often thickened; distal and median laminal cells short or long, quadrate, rectangular or irregularly angled, proximal cells rectangular to linear, alar cells inflated, 1- or 2-stratose, rarely more, generally orange to brown, rarely poorly differentiated. Specialized asexual reproduction lacking or as clusters of 1--6, deciduous, terete, flagelliform branchlets, borne in axils of distal leaves. Sexual condition dioicous or pseudomonoicous; male plants as large as female plants or dwarfed and epiphytic on stem rhizoids of female plants; perigonial leaves ovate, concave, short-acuminate; perichaetial leaves convolute-sheathing, abruptly subulate or rarely interior leaves gradually acuminate. Seta solitary or up to 6 per perichaetium, smooth, elongate, erect, twisted when dry, yellow, brown or reddish. Capsule erect or inclined, cylindric, straight or arcuate, smooth, striate or furrowed when dry, annulus of 1--3 rows of usually large, deciduous or persistent cells, sometimes indistinctly differentiated; operculum long-rostrate, straight or arcuate; peristome single, 16 teeth, split 1/3--1/2 their length into 2, rarely 3, divisions, vertically pitted-striolate below, papillose above, reddish brown. Spores 12--30 µm, spherical, finely papillose. Calyptra cucullate, smooth, naked, covering most of capsule, fugacious.

Species ca.140 (26 in the flora): North, Central and South America, Europe; Asia, Africa, and Australia.

For this flora the segregate genus Orthodicranum is not recognized. Whether to recognize this genus or not has been debatable for years. W. Peterson (1979) listed the following six characters that he considered important in separating this segregate from Dicranum: (1) capsules straight vs. capsules curved; (2) capsules smooth to slightly wrinkled vs. capsules ribbed; (3) alar cells 1-stratose vs. alar cells 2-stratose; (4) peristome teeth relatively narrow (ca. 60 µm) vs. peristome teeth relatively wide (70--95 µm or more); (5) specialized asexual reproduction by broken leaf tips or flagellated branches common vs. specialized asexual reproduction rare; (6) specialized habitat of rocks and wood vs. habitat of wood or rock rare, usually on soil or humus. The species placed in Orthodicranum by him as well as by other bryologists are D. flagellare, D. fulvum, D. montanum, D. tauricum and D. viride. Dicranum fragilifolium is another species in our flora that has been placed there by some bryologists (e.g., J. Podpěra 1954). The problem with recognizing the genus Orthodicranum is that some of the members otherwise remaining in Dicranum share one or more of the six character states Peterson outlined for the segregate genus. Dicranum fragilifolium and D. rhabdocarpa are two of the species that commonly have some of the characters of Orthodicranum and some of those of Dicranum. Other species in Dicranum less commonly have characters of both genera. If for no other reason but the sake of utility it is more practical at this time to leave all the species in one genus so they can be keyed out together and compared more readily. Perhaps when a world monograph of the genus Dicranum is done it will become more evident whether it is important to recognize Orthodicranum and perhaps even other segregate genera.

Leaf cross sections of the leaves employed in this treatment are necessary to observe cell features of the costa and laminal cells. The costa stereid and guide cells, the adaxial and abaxial epidermal cells, the number of layers of alar and laminal cells and the bulges in the cell walls between the laminal cells are all observable in cross section. These characters are extremely important because they can reliably differentiate many species of Dicranum. The leaf cross section characters are usually less variable and less influenced by the environment than other gametophytic characters, such as leaf habit, shape, margins and costa length characters, and are utilized to a great extent since they are considered much more dependable in species identification than some of the other characters in the genus.


Dicranum arcticum Schimper, Musci Eur. Nov. Bryol. Eur. Suppl. fasc. 3-4 Mon. Dicranum 3.3. 1866 = Kiaeria glacialis (Berggren) I. Hagen, K. Norsk. Vid. Selsk. Skrift. 1914 (1): 125. 1915 (Dicranum glaciale Berggren, Lunds Univ. Års-skr. Afd. Math. Nat. 2(7): 19. 1-9. 1866). Dicranum longifolium Hedwig, Spec. Musc.130. 1801 = Paraleucobryum longifolium (Hedwig) Loeske, Hedwigia 47: 171. 1908. Dicranum subporodictyum (Brotherus) C. H. Gao & T. Cao, Bryobrothera 1: 218. 1992 (Dicranodontium subporodictyon Brotherus, Symb. Sin. 4: 20. 1929) = Campylopus subporodictyon (Brotherus) B. H. Allen & Ireland, Lindbergia (In press).


Allen, B. 1998a. The genus Orthodicranum (Musci: Dicranaceae) in Maine. Evansia 15(1): 9--20. Allen, B. 1998b. The genus Dicranum (Musci: Dicranaceae) in Maine. Evansia 15(2): 45--80. Bellolio-Trucco, G. and R. R. Ireland. 1990. A taxonomic study of the moss genus Dicranum (Dicranaceae) in Ontario and Quebec. Canadian Journal of Botany 68(4): 867--909. Chien, G., D.H. Vitt and S. He. 1999. Dicranum. Pp. 163--193. In G. Chien and M.R. Crosby(Editors), Moss Flora of China, Vol. 1. Sphagnaceae-Leucobryaceae. Bejing, New York and St. Louis. Crum, H. A. and L. E. Anderson. 1981. Mosses of Eastern North America. Vol. 1. New York. Ireland, R. R. 1971. Dicranum. In E. Lawton, Moss Flora of the Pacific Northwest. Pp. 72--81, pl. 29--33. The Hattori Botanical Laboratory, Nichinan, Japan. Ireland, R. R. 1982. Moss Flora of the Maritime Provinces. National Museums of Canada , Nat. Mus. Nat. Sciences, Publs. in Botany, No. 13. Ottawa. Nyholm, E. 1986. Illustrated flora of Nordic mosses. Fasc. I. Fissidentaceae-Seligeriaceae. Odense. Peterson, W. 1979. A revision of the genera Dicranum and Orthodicranum (Musci) in North America north of Mexico. 453 pp. Ph.D. thesis, University of Alberta, Edmonton. Williams, R. S. 1913. Dicranaceae. N. Amer. Flora 15(2): 77--166.


Briggs, D. 1965. Experimental taxonomy of some British species of the genus Dicranum. New Phytol. 64: 366--386.
Correns, C. 1899. Untersuchungen über die Vermehrung der Laubmoose durch Brutorgane und Stecklinge. Jena.
Eversman, S. and A.J. Sharp. 1980. First checklist of Montana mosses. Proc. Montana Acad. Sci. 39: 12--24.
Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University Press, Provo.
Haring, I.M. 1961. A checklist of the mosses of the state of Arizona. The Bryologist 64 (2--3):222--240.
Hegewald, E. 1972. Dicranum groenlandicum in Finland. Memo. Soc. Fauna Flora Fenn. 48: 85--87.
Hilferty, F.J. 1960. The mosses of Massachusetts. A county catalogue with annotations. Rhodora 62: 145--173.
Holzinger, J.M. 1925. Dr. Brotherus’ treatment of Dicranum. The Bryologist 28: 22.
Ireland, R.R. 1966 (1965). Dicranum pallidisetum in western North America. The Bryologist 68(4): 446--450.
Isoviita, P. 1977. On Dicranum drummondii and D. ontariense (Musci). Ann. Bot. Fenn. 14: 153--156.
Löve, D., J. Kucyniak, and D. Gordon. 1958. A plant collection from interior Quebec. Nat. Can. (Que.) 85: 25--69.
Melnichuk, V.M. 1970. Classification key of the frondiferous mosses of the central and south regions of the European USSR. Akademia Nauk Ukrainskoi SSSR, Kiev.
Mönkemeyer, W. 1927. Die Laubmoose Europas, Andreaeales-Bryales. In L. Rabenhorst, Kryptogamen-Flora von Deutschland, Österreich und der Schweiz. Vol. 4. Leipzig.
Peterson, W. 1977. Dicranum ontariense Peterson: a new name for a North American endemicmoss. Can. J. Bot. 55: 986--991.
Podpêra, J. 1954. Conspectus muscorum Europaeorum. Czechoslovakia Academy, Prague.
Renauld, F. and J. Cardot. 1889. New mosses of North America. II. Bot. Gaz. 14: 91--100.
Savich-Lyubitskaya, L.I. and Z.N. Smirnova. 1970. The handbook of the mosses of the U.S.S.R. Komarov Botanical Institute, Leningrad.
Sérgio, C., R. Ochyra and A. Séneca. 1995. Dicranum crassifolium (Musci, Dicranaceae), a new species from southern Europe. Fragm. Flor. Geobot. 40(1): 203--214.
Smith, A.J.E. 1978. The Moss Flora of Britain and Ireland. London.
Snider, J.A. & B.K. Andreas. 1996. A catalogue and atlas of the mosses of Ohio. Ohio Biological Survey, Misc. Contr. No. 2. Ohio State University, Columbus.
Snider, J.A., S.M. Studlar and M. Medley. 1988. A list of the bryophytes of Kentucky. The Bryologist 91(2): 98--105.
Tuomikoski, R., T. Koponen and T. Ahti. 1973. The mosses of the island of Newfoundland. Ann. Bot. Fennici 10: 217--264.
Weber, W.A. 1973. Guide to the mosses of Colorado. Occas. Pap. Inst. Arctic Alpine Res. 6. 48 pp.
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1 Leaves mostly straight, erect-spreading, the tips deciduous and lacking.   (2)
+ Leaves rarely straight, usually crisped or falcate, the tips mostly present.   (4)
2 (1) Costa lacking stereid bands, with 1--2 layers of cells above and below the guidecells in the basal part of the leaf; alar cells 1-stratose; capsule straight, erect; w North America.   Dicranum tauricum
+ Costa with stereid bands, although sometimes weak, with 2--3 layers of cells above and below the guide cells in the basal part of the leaf; alar cells 1- or 2-stratose; capsule straight and erect or arcuate; w or more often e North America.   (3)
3 (2) Leaves shiny, with proximal cells pitted, distal cells rectangular, alar cells 2-stratose or with a few 1-stratose regions, lamina rarely with 2-stratose regions.   Dicranum fragilifolium
+ Leaves dull, with proximal cells not pitted (or with few pits), distal cells quadrate, alar cells 1-stratose or with few 2-stratose regions, lamina often with 2-stratose regions.   Dicranum viride
4 (1) Distal leaf cells usually elongate, sinuose, pitted.   (5)
+ Distal leaf cells usually short (quadrate, rectangular, or irregularly angled), neither sinuose nor pitted (or with few pits).   (14)
5 (4) Costa with 2 rows of guide cells, without abaxial ridges; leaves 10--15 mm; setae often aggregate.   Dicranum majus
+ Costa with 1 row of guide cells, often with abaxial ridges; leaves often less than 10 mm; setae solitary or aggregate.   (6)
6 (5) Leaves keeled distally, margins strongly serrate to toothed in distal half; costa with 2--4 well-developed dentate ridges on abaxial surface in distal part of leaf.   (7)
+ Leaves tubulose to somewhat keeled distally, margins entire to serrate in distal half; costa without or with poorly developed dentate ridges distally on abaxial surface.   (9)
7 (6) Leaves spreading, strongly undulate; setae aggregate, 3--5 per perichaetium.   Dicranum polysetum
+ Leaves falcate-secund, not or slightly undulate; setae solitary, rarely 2 per perichaetium.   (8)
8 (7) Interior perichaetial leaves gradually acuminate; endemic to w NorthAmerica.   Dicranum howellii
+ Interior perichaetial leaves abruptly acuminate; throughout most of North America.   Dicranum scoparium
9 (6) Costa subpercurrent to percurrent; alar cells usually 1-stratose, rarely 2-stratose inpart; capsule slightly arcuate to straight and erect.   (10)
+ Costa subpercurrent to excurrent; alar cells 2-stratose; capsule slightly to strongly arcuate.   (11)
10 (9) Leaves spreading to slightly falcate-secund, margins serrate near apex; capsule 2--4 mm; endemic to w North America.   Dicranum rhabdocarpum
+ Leaves erect-spreading to erect-appressed, margins entire; capsule 1.5--2 mm; across n North America.   Dicranum groenlandicum
11 (9) Leaves with a long, narrow subula, apex acute to somewhat obtuse.   Dicranum spadiceum
+ Leaves with a short subula, apex obtuse to somewhat acute.   (12)
12 (11) Leaves usually with twisted apex when dry; portion of some stemsjulaceous and composed of short, broad, concave, appressed, somewhat obtuse leaves; proximal leaf margins ± involute.   Dicranum leioneuron
+ Leaves seldom or never with twisted apex when dry; without julaceous portions of stems; proximal leaf margins flat.   (13)
13 (12) Leaves rugose-undulate, shiny, cells smooth on abaxial surface.   Dicranum bonjeanii
+ Leaves not or little rugose-undulate, dull, cells often somewhat rough on abaxial surface (form).   Dicranum scoparium
14 (4) Proximal leaf cells not pitted (or with few pits); alar cells usually 1-stratose, rarely 2-stratose; capsule generally straight; plants averaging 2--4 cm.   (15)
+ Proximal leaf cells pitted; alar cells 1- or often 2-stratose; capsule generally arcuate; plants averaging 3--8 cm.   (17)
15 (14) Leaf lamina mostly 2-stratose above, costa usually more than 1/4 the width of leaf base; usually on rock, rarely on corticolous substrates.   Dicranum fulvum
+ Leaf lamina 1-stratose above, costa less than 1/4 the width of leaf base; common on wood and humus, sometimes on soil or rock.   (16)
16 (15) Plants with 2--6 flagelliform branchlets (rigid and terete branches with appressed leaves) in the distal leaf axils; brood branches lacking; leaves tubulose distally and slightly papillose on abaxial surface, curled to crisped when dry; distal leaf cells short-rectangular to quadrate.   Dicranum flagellare
+ Plants lacking flagelliform branchlets; usually with weak, slender, broodbranches with linear, strongly crisped leaves when dry; leaves semi-keeled distally and strongly papillose on abaxial surface, generally strongly cirrate when dry; distal leaf cells regularly quadrate.   Dicranum montanum
17 (14) Leaves tubulose in distal half; costa often indistinct and scarcely prominent on abaxial surface.   (18)
+ Leaves keeled in the distal half; costa prominent and rounded on abaxial surface.   (21)
18 (17) Leaf cells strongly papillose in distal half of leaf; costa without stereids in distal 1/4--1/3 of leaf, adaxial and abaxial epidermal layer of cells not or scarcely differentiated; capsule sometimes strumose, 1--3 per perichaetium; endemic to nw North America.   Dicranum pallidisetum
+ Leaf cells smooth or weakly papillose in distal half of leaf; costa with stereid bands in distal part of leaf as well as below, adaxial and abaxial epidermal layer of cells sometimes differentiated; capsule not strumose, solitary; across North America.   (19)
19 (18) Leaves cirrate to crisped when dry; distal leaf cells short-rectangular to quadrate, with thin walls, proximal cells 9--12 ìm wide; costa with adaxial epidermal layer of cells enlarged (seen in cross section near leaf middle); capsule 2--4 mm.   Dicranum muehlenbeckii
+ Leaves erect-appressed or slightly curled when dry; distal leaf cells elliptical to rectangular, with thick walls, proximal cells 5--6 µm wide; costa with only a few cells in adaxial epidermal layer enlarged; capsule 1--2 mm.   (20)
20 (19) Proximal leaves with acute apices; proximal leaf cells usually less than 40 µm, median cells pitted mainly proximal to middle of leaf.   Dicranum elongatum
+ Proximal leaves often with blunt apices; proximal leaf cells usually morethan 40 µm, median cells pitted well distal above middle of leaf.   Dicranum groenlandicum
21 (17) Leaves plane or indistinctly undulate near apex.   (22)
+ Leaves undulate or rugose (Dicranum condensatum indistinctly undulate).   (24)
22 (21) Leaves strongly cirrate to crisped when dry, proximal cells usually more than 45 µm; cells walls between lamina cells strongly bulging as seen in cross section; capsules 3--4 mm.   Dicranum brevifolium
+ Leaves straight to ± curled when dry, proximal cells usually more than 45 µm; cell walls smooth or only slightly bulging between lamina cells as seen in cross section; capsules 1--3 mm.   (23)
23 (22) Leaves with distal margins ± involute, laminae with few 2-stratoseregions on margins in the distal part; leaf cells smooth to slightly papillose on abaxial surface in distal part of leaf.   Dicranum acutifolium
+ Leaves with distal margins erect, laminae with one or both distal margins 2-stratose; leaf cells papillose on abaxial surface in distal part of leaf.   Dicranum fuscescens
24 (21) Costa ending well before apex, rarely nearly percurrent.   Dicranum undulatum
+ Costa percurrent to excurrent.   (25)
25 (24) Leaves erect-spreading to erect and compressed when moist; distal-median leaf cells irregularly angled, with unequally thickened walls; capsule 1.5--2 mm, slightly contracted below mouth.   (26)
+ Leaves falcate-secund when moist; distal-median leaf cells short- rectangular to quadrate, with equally thickened walls; capsule 2--4 mm, not contracted below mouth.   (28)
26 (25) Leaves gradually narrowed to a long-acuminate apex; costa with a few differentiated cells in adaxial epidermal layer, cell walls between lamina cells not bulging; nw North America.   Dicranum drummondii
+ Leaves acute to gradually narrowed to a short-acuminate apex; costa lacking differentiated cells in adaxial epidermal layer, cell wallsbetween lamina cells weakly to strongly bulging; e North America.   (27)
27 (26) Leaves ovate to ovate-lanceolate, concave and arched, loosely imbricate when dry.   Dicranum spurium
+ Leaves broadly lanceolate, not arched, slightly crisped when dry, not imbricate.   Dicranum condensatum
28 (25) Leaf margins strongly toothed distally, laminae with tooth-like projections scattered distally on abaxial surface; setae often aggregate, 1--5 per perichaetium; capsule not strumose.   Dicranum ontariense
+ Leaf margins slightly serrate distally, laminae smooth to slightly rough distally on abaxial surface; seta always solitary; capsule ± strumose.   (29)
29 (28) Leaves strongly crisped to cirrate when dry, proximal leaf cells usually less than 45 µm; stems densely tomentose.   Dicranum brevifolium
+ Leaves straight to curled when dry, proximal leaf cells oftenmore than 45 µm; stems somewhat tomentose.   Dicranum acutifolium

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