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 XX.     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, margins plane to incurved or involute, entire to serrate in distal part, entire proximally, apex acute to obtuse, tips sometimes deciduous, apparently a means of asexual reproduction; laminae 1- or 2-stratose at margins or sometimes near costa; costa single, ending before apex to excurrent, smooth or toothed on abaxial surface, sometimes with 2–4 serrated ridges abaxially, 1–2 rows of guide cells, 2 well-developed stereid bands above and below, sometimes slightly differentiated or lacking, extending to apex, or ending before the apex, 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, erect, twisted when dry, yellow, brown or reddish, elongate, smooth.  Capsule erect or inclined, straight or arcuate, cylindric, 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 or, rarely, 3 divisions, vertically pitted-striolate proximally, papillose above, reddish brown.  Spores spheric, 12–30 µm, finely papillose.  Calyptra fugacious, cucullate, smooth, naked, covering most of capsule,

Species ca. 140 (26 in the flora): North America, Central America, 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 debated 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. Podpera 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.

SELECTED REFERENCES    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.

1.     Leaves mostly straight, erect-spreading, the tips deciduous and lacking.

2.     Costa lacking stereid bands, with 1–2 layers of cells above and below the guide cells in the basal part of leaf; alar cells 1-stratose; capsule straight, erect; w North America..........................
.......................................................................................................................... 24.   Dicranum tauricum

2.     Costa with stereid bands, although sometimes weak, with 2–3 layers of cells above and below the guide cells in the basal part of leaf; alar cells 1- or 2-stratose; capsule straight and erect or arcuate; w or more often e North America.

3.     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.........................................
............................................................................................................ 21.   Dicranum fragilifolium

3.     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................ 23.   Dicranum viride

1.     Leaves rarely straight, usually crisped or falcate, the tips mostly present.

4.     Distal leaf cells usually elongate, sinuose, pitted.

5.     Costa with 2 rows of guide cells, without abaxial ridges; leaves 10–15 mm; setae often aggregate......................................................................................................... 6.   Dicranum majus

5.     Costa with 1 row of guide cells, often with abaxial ridges; leaves often less than 10 mm; setae solitary or aggregate.

6.     Leaves keeled distally, margins strongly serrate to toothed in distal 1/2; costa with 2–4 well-developed dentate ridges on abaxial surface in distal part of leaf.

7.     Leaves spreading, strongly undulate; setae aggregate, 3–5 per perichaetium..... 1.   Dicranum polysetum

7.     Leaves falcate-secund, not or slightly undulate; setae solitary, rarely 2 per perichaetium.

8.     Interior perichaetial leaves gradually acuminate; endemic to w NorthAmerica.............................................................................................. 3.   Dicranum howellii

8.     Interior perichaetial leaves abruptly acuminate; throughout most of North America........................................................................... 2.   Dicranum scoparium

6.     Leaves tubulose to somewhat keeled distally, margins entire to serrate in distal 1/2; costa without or with poorly developed dentate ridges distally on abaxial surface.

9.     Costa subpercurrent to percurrent; alar cells usually 1-stratose, rarely 2-stratose inpart; capsule slightly arcuate to straight and erect.

10.   Leaves spreading to slightly falcate-secund, margins serrate near apex; capsule 2–4 mm; endemic to w North America. 7.   Dicranum rhabdocarpum

10.   Leaves erect-spreading to erect-appressed, margins entire; capsule 1.5–2 mm; across n North America............................. 20.   Dicranum groenlandicum

9.     Costa subpercurrent to excurrent; alar cells 2-stratose; capsule slightly to strongly arcuate.

11.   Leaves with a long, narrow subula, apex acute to somewhat obtuse...............
....................................................................................... 17.   Dicranum spadiceum

11.   Leaves with a short subula, apex obtuse to somewhat acute.

12.   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......................................... 5.   Dicranum leioneuron

12.   Leaves seldom or never with twisted apex when dry; without julaceous portions of stems; proximal leaf margins flat.

13.   Leaves rugose-undulate, shiny, cells smooth on abaxial surface................... 4.   Dicranum bonjeanii

13.   Leaves not or little rugose-undulate, dull, cells often somewhat rough on abaxial surface.................................................... 2.   Dicranum scoparium (form)

4.     Distal leaf cells usually short (quadrate, rectangular, or irregularly angled), neither sinuose nor pitted (or with few pits).

14.   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.   Leaf lamina mostly 2-stratose above, costa usually more than 1/4 width of leaf base; usually on rock, rarely on corticolous substrates......................... 22.   Dicranum fulvum

15.   Leaf lamina 1-stratose above, costa less than 1/4 width of leaf base; common on wood and humus, sometimes on soil or rock.

16.   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.................................... 26.   Dicranum flagellare

16.   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............................................... 25.   Dicranum montanum

14.   Proximal leaf cells pitted; alar cells 1- or often 2-stratose; capsule generally arcuate; plants averaging 3–8 cm.

17.   Leaves tubulose in distal 1/2; costa often indistinct and scarcely prominent on abaxial surface.

18.   Leaf cells strongly papillose in distal 1/2 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............................................................ 16.   Dicranum pallidisetum

18.   Leaf cells smooth or weakly papillose in distal 1/2 of leaf; costa with stereid bands in distal part of leaf as well as proximally, adaxial and abaxial epidermal layer of cells sometimes differentiated; capsule not strumose, solitary; across North America.

19.   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.................................................... 18.   Dicranum muehlenbeckii

19.   Leaves erect-appressed or slightly curled when dry; distal leaf cells elliptic 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.   Proximal leaves with acute apices; proximal leaf cells usually less than 40 μm, median cells pitted mainly proximal to middle of leaf.................. 19.   Dicranum elongatum

20.   Proximal leaves often with blunt apices; proximal leaf cells usually morethan 40 µm, median cells pitted well distal above middle of leaf.. 20.   Dicranum groenlandicum

17.   Leaves keeled in distal 1/2; costa prominent and rounded on abaxial surface.

21.   Leaves plane or indistinctly undulate near apex.

22.   Leaves strongly cirrate to crisped when dry, proximal cells usually less than 45 µm; capsule 3–4 mm............................................. 13.   Dicranum brevifolium

22.   Leaves straight to ± curled when dry, proximal cells usually more than 45 µm; capsule 1–3 mm.

23.   Leaves with distal margins ± involute, laminae with few 2-stratoseregions on margins in distal part; leaf cells smooth to slightly papillose on abaxial surface in distal part of leaf 14.   Dicranum acutifolium

23.   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..................................................................... 15.   Dicranum fuscescens

21.   Leaves undulate or rugose (Dicranum condensatum indistinctly undulate).

24.   Costa ending well before apex, rarely nearly percurrent 8.   Dicranum undulatum

24.   Costa percurrent to excurrent.

25.   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 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.........................................
..................................................................... 10.   Dicranum drummondii

26.   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.   Leaves ovate to ovate-lanceolate, concave and arched, loosely imbricate when dry.................... 12.   Dicranum spurium

27.   Leaves broadly lanceolate, not arched, slightly crisped when dry, not imbricate............................ 11.   Dicranum condensatum

25.   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.   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.................. 9.   Dicranum ontariense

28.   Leaf margins slightly serrate distally, laminae smooth to slightly rough distally on abaxial surface; seta always solitary; capsule ± strumose.

29.   Leaves strongly crisped to cirrate when dry, proximal leaf cells usually less than 45 µm; stems densely tomentose................ 13.   Dicranum brevifolium

29.   Leaves straight to curled when dry, proximal leaf cells often more than 45 µm; stems somewhat tomentose 14.   Dicranum acutifolium

1.   Dicranum polysetum   Swartz, Monthl. Rev. 34: 538.  1801

Dicranum rugosum (Funck) Bridel

Plants in loose tufts, light green, glossy.  Stems 4–15 cm, densely tomentose with whitish or reddish rhizoids.  Leaves erect to spreading, ± flexuose, little changed when dry, strongly undulate, (5.5–)7–9.5(–10.5) × 1–2 mm, lanceolate, concave proximally, keeled above, acute, margins strongly toothed in distal 1/2; laminae 1-stratose; costa ending before apex, occupying ca. 1/16–1/8 of leaf base, strong, with 2 toothed ridges distally on abaxial surface, with 1 row of guide cells, 2 stereid bands, adaxial epidermal layer of cells not differentiated, abaxial layer with a few cells enlarged; cell walls between lamina cells not bulging; leaf cells smooth; alar cells 2-stratose, well differentiated, not extending to costa; proximal laminal cells elongate, pitted, (45–)78–129(–156) × (5–)9–10(–14) µm; distal laminal cells shorter, sinuose, pitted, (42–)64–68(–115) × (4–)9–10(–13) µm.  Sexual condition pseudomonoicous; dwarf male plants on stem rhizoids of female plants; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta usually aggregate, 3–6 per perichaetium, brown or reddish brown, 1.5–4 cm.  Capsule arcuate, inclined to horizontal, yellowish brown or reddish brown, 2–3.5 mm, furrowed when dry; operculum 2–4 mm.  Spores 12–24 µm.

Capsules mature in spring.  Commonly on humus, soil over acidic or calcareous rocks, and decaying wood in deciduous or more often coniferous forests, occasionally in bogs, fens, and swamps; 10–2100 m; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Alaska, Colo., Conn., Idaho, Ill., Ind., Iowa, Ky, Maine, Md., Mass., Mich., Minn., Mo., Mont., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Oreg., Pa., S.Dak., Tenn., Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; Asia.

This Dicranum is the largest, the most conspicuous and the most easily recognized species in the genus in North America.  The species is immediately recognized by the large stems, 4–15 cm, with a dense mat of whitish or reddish tomentum, giving the stems a thickened appearance, by the shiny, strongly undulate, wide-spreading leaves with margins strongly toothed in distal 1/2 and by the clustered sporophytes (3–6 per perichaetium).  Microscopically, the species is readily distinguished by the elongate, abundantly pitted cells throughout the leaf and by the toothed ridges on the abaxial surface of the costa in the distal part of the leaf.  Dicranum polysetum is one of the few species in North America that has no apparent intergradations with any other species of Dicranum. 

Dicranum polysetum is common in southeastern Canada, northeastern United States and the Canadian Rocky Mountains where it extends south to Wyoming and Colorado, occurring in both states in a small number of localities.  It is rare west of the Rockies where it is known from only a few localities in northwestern Montana, southern Idaho and northeastern Washington and Oregon.  The Nunavut record is from W. Peterson (1979).

2.   Dicranum scoparium   Hedwig, Spec. Musc. 126.  1801

Dicranum latifolium J. J. Amann

Plants in loose to dense tufts, light to dark green, glossy to sometimes dull.  Stems 2–10 cm, tomentose with white to brown rhizoids.  Leaves very variable, usually falcate-secund, rarely straight and erect, slightly contorted and crisped when dry, sometimes slightly rugose or undulate, (4–)5–8.5(–15) × 0.8–1.8 mm, concave proximally, keeled above, lanceolate, apex acute to somewhat obtuse, margins strongly serrate in distal 1/3 or rarely slightly serrulate; laminae 1-stratose; costa percurrent, excurrent, or ending before apex, 1/10–1/5 width of leaves at base, usually with 2–4 toothed ridges above on abaxial surface, with a row of guide cells, 2 thin stereid bands, adaxial epidermal layer of cells not differentiated, abaxial layer interrupted by several enlarged cells that form part of the abaxial ridge, not extending to the apices; cell walls between lamina cells not bulging; leaf cells smooth; alar cells 2-stratose, well- differentiated, sometimes extending to costa; proximal laminal cells linear-rectangular, pitted, (25–)47–100(–132) × (5–)7–12(–13) µm; distal laminal cells shorter, broad, sinuose, pitted, (11–)27–43(–53) × (5–)8–12(–20) µm.  Sexual condition pseudomonoicous or dioicous; dwarf males on rhizoids of female plants or male plants as large as females; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta solitary, rarely 2 per perichaetium, yellowish brown to reddish brown, 2–4 cm.  Capsule arcuate, inclined to horizontal, yellowish brown or reddish brown, 2.5–4 mm, smooth to striate when dry; operculum 2–3.5 mm.  Spores 14–24 µm.

Capsules mature in spring.  Soil, humus, humus over rocks, decaying stumps and logs, tree bases in dry to mesic woodlands; sometimes bogs, fens and swamps; 50–2900 m; Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico; Europe; Asia; Australia; New Zealand.

Undoubtedly the most polymorphic species of Dicranum in North America.  It is commonly called the broom moss because the leaves are “swept” or turned in the same direction.  However, the habit of the leaves varies from strongly falcate-secund, i.e., the swept state, to straight and erect, especially prevalent in northern plants.  The leaf shape varies from the typical lanceolate and long-acuminate to the odd ovate-lanceolate and short-acuminate.  The leaves are typically smooth, in sharp contrast to the strongly undulate leaves of D. polysetum, but on rare occasion they can be somewhat undulate-rugose.  The leaf margins are usually distinctly toothed in the distal third but at times plants in some populations have extremely weak serrations, appearing nearly entire.  The costae vary in extent from subpercurrent to shortly excurrent.  The abaxial surface of the costae have two to four toothed ridges, compared to the two in D. polysetum, but in some forms they are almost nonexistent.  The distal areolation of the leaves seems to remain constant in the myriad forms of D. scoparium, the cells are short-sinuose with pitted walls, generally containing conspicuous oil-drops.

Plants growing in Arctic North America and those in extremely wet habitats, such as bogs, often have a different superficial appearance.  The leaves are straight, erect, ovate-lanceolate, short-acuminate with weak serrations on the margins, and the abaxial ridges on the costae are poorly developed.  Sometimes the plants have distal shoots with abnormal appearing leaves that are shorter and broader than those below.  Some of these collections have been referred to D. latifolium J. J. Amann, a species that I consider to be a synonym of D. scoparium.  Further field and laboratory studies are required to clarify the taxonomic status of these plants. In the sterile state, large-leaved plants of D. scoparium can be confused with D. majus.  The latter is immediately distinguished by a double row of guide cells, instead of the single row in the former, thicker stereid bands, distal cells that are narrower and more elongate and costae that have small teeth or serrulations distally on the abaxial surface instead of the characteristic 2–4-toothed ridges of D. scoparium. When fruiting, the solitary, rarely paired, sporophytes of D. scoparium distinguish it from D. majus which has multiple sporophytes, 2–5 per perichaetium.

3.   Dicranum howellii   Renauld & Cardot, Rev. Bryol. 15: 70.  1888    E

Plants in loose to dense tufts, green to yellowish green, glossy.  Stems 2–8 cm, densely tomentose with white to reddish brown rhizoids.  Leaves falcate-secund to straight and erect, sometimes slightly crisped, smooth, (5–)8–10(–12) ´ 0.8–1.5 mm, concave proximally, keeled or tubulose above, lanceolate, apex acute, margins strongly serrate in distal part, entire proximally; laminae 1-stratose; costa ending before apex to shortly excurrent, 1/12–1/5 width of leaves at base, with 2, rarely 4, toothed ridges on abaxial surface extending from ca. leaf middle nearly to apex, rarely almost smooth, with a row of guide cells, 2, thin stereid bands, adaxial epidermal layer of cells not differentiated, abaxial layer interrupted by several enlarged cells that form part of abaxial ridge, not extending to apices; cell walls between lamina cells not bulging; leaf cells smooth; alar cells 2-stratose, well differentiated, sometimes extending to costa; proximal laminal cells linear-rectangular, pitted, (52–)65–105(–120) × (10–)12–18(–22) µm; distal laminal cells shorter, sinuose, pitted, (42–)54–90(–108) × (10–)12–14(–16) µm.  Sexual condition pseudomonoicous or dioicous; dwarf males on rhizoids of female plants or male plants as large as females and growing intermixed or in ± separate tufts; interior perichaetial leaves gradually acuminate, not or partially convolute-sheathing.  Seta solitary, sometimes 2 per perichaetium, yellow to reddish brown, 1.5–4 cm.  Capsule arcuate, inclined to horizontal, yellow to dark reddish brown, 2–3.8 mm, smooth to striate when dry; operculum 2–3.8 mm.  Spores 18–26 µm.

Capsules mature in spring.  Soil, humus, humus over rocks, rotting logs and stumps, tree trunks and bases of trees, sometimes in bogs; 20–600 m; B.C.; Alaska, Calif., Idaho, Mont., Oreg., Wash.

Dicranum howellii is one of five endemic species of North America, occurring only in the northwestern part of the continent.  It is closely related to the common and nearly ubiquitous D. scoparium.  The shape of the interior perichaetial leaves is the most reliable way to distinguish the two.  Gradually acuminate interior perichaetial leaves that loosely surround the seta are characteristic of D. howellii while D. scoparium has abruptly acuminate interior perichaetial leaves that are convolute-sheathing around the seta.  The exterior perichaetial leaves also exhibit the same characteristic but to a lesser extent.  The interior perichaetial leaves of D. howellii are also longer and narrower than those of the latter.  Other less significant features of D. howellii are the consistently glossy, long leaves, mostly 8–10 mm, with long distal cells, averaging 54–90 mm, and the common occurrence of only two, rarely four, serrated ridges on the abaxial surface of the costae.  Dicranum scoparium by comparison has glossy to sometimes dull leaves that are often shorter, mostly 5–8.5 mm, with shorter distal cells, averaging 27–43 mm, and the costae usually have four, rarely two, serrated ridges on the abaxial surface.  The perichaetial leaves are undoubtedly the most important feature separating the two species, as well as being the easiest to observe.  Eastern North American plants of D. scoparium all have the abruptly acuminate perichaetial leaves that are characteristic of the species as do plants elsewhere in the world.  The perichaetial leaf character was one reason D. howellii was believed to be a distinct species by F. Renauld and J. Cardot (1889, Pl. 12B) who first illustrated that character and this remains the most significant reason for maintaining it as a distinct species.

4.   Dicranum bonjeanii   De Notaris in Lisa, Elenco Muschi Torino 29.  1837

Plants in loose tufts, yellow to yellowish green, glossy.  Stems 2–8 cm, scarcely tomentose with whitish to reddish brown rhizoids.  Leaves erect-spreading, sometimes nearly appressed, flexuose, little changed when dry, undulate or rugose, (3.5–)4–5.5(–6) × 1–1.5 mm, flat to ± concave proximally, subtubulose above, from a lanceolate base to a short, broadly acute apex, distal part of stem often with ovate, short-subulate, blunt leaves, margins serrate in distal 1/2; laminae 1-stratose; costa ending just before the apex, sometimes with 2 poorly developed toothed ridges above on abaxial surface, 1/13–1/8 width of leaves at base, row of guide cells, 2 thin stereid bands, adaxial epidermal layer of cells not differentiated, abaxial layer with a few (usually 2) cells differentiated in distal part of leaves; cell walls between lamina cells not bulging; leaf cells smooth; alar cells 2-stratose, well-differentiated, sometimes extending to costa; proximal laminal cells long, sinuose, pitted, (28–)47–71(–113) × (–5)9–11(–14) µm; distal laminal cells short-linear, sinuose, pitted, (25–)36–51(–73) × (5–)8–14(–20) µm.  Sexual condition pseudomonoicous; dwarf males on rhizoids of female plants; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta solitary, rarely 2 per perichaetium, yellowish brown to reddish brown, 2.5–3.5 cm.  Capsule arcuate, inclined to horizontal, yellow-brown, 2.5–3 mm, striate when dry; operculum 1.7–3 mm.  Spores 14–28 µm.

Capsules mature in spring.  Mainly in eutrophic fens, sometimes on calcareous soil or rocks; 60–1300 m; Greenland; Alta, B.C., Man., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask.; Alaska, Colo., Idaho, Maine, Mich., Ohio, Oreg., Mass., Pa., Vt., Wash., Wis., Wyo.; Europe; Asia.

Dicranum bonjeanii is a difficult species to distinguish from the myriad forms of the polymorphic D. scoparium.  Indeed, few of the many herbarium collections from North America named D. bonjeanii are actually that species or at least what is known as that species.  It has been noted before (R. R. Ireland 1982) that it may be merely an enviromental form growing in a calcareous, often hydric habitat.  Most Europeans (e.g., A. J. E. Smith 1978; E. Nyholm 1986) recognize the species as it occurs in Europe and some that come to North America to collect (e.g., R. Tuomikoski et al. 1973) find the species to be distinct on this continent.  However, H. A. Crum and L. E. Anderson (1981) and other North American bryologists have synonymized the species with D. scoparium.  D. Briggs (1965), who cultivated and studied British plants of both D. bonjeanii and D. scoparium under controlled environmental conditions, found that while they show wide intraspecific variation, especially in regard to the leaf habit and undulation, he thought they should be kept as separate taxa because each species maintains a distinctive array of gametophytic characters. Also, both species are distinctive ecologically:  D. bonjeanii prefers eutrophic fens, whereas D. scoparium usually grows in decidedly dry to mesic woodlands, on soil, humus, humus over rock, stumps and logs, tree bases, etc.

The species is best known by its glossy, mostly erect, nearly straight, undulate leaves with broadly acute apices, weakly developed marginal teeth and, what is most important, two poorly developed ridges present only near the leaf apex on the abaxial surface of the costa. The two ridges on the costa, best seen in cross section, will distinguish the species most of the time from D. scoparium which usually has four ridges on its costae. Its preference for eutrophic fens and other calcareous habitats, while avoiding acid substrates, is important from an ecological standpoint and helps give a clue to the identity of the species.

The Maine record is from B. Allen (1998b).

5.   Dicranum leioneuron   Kindberg in Macoun, Bull. Torrey Bot. Club 16: 92.  1889

Plants in loose tufts, yellowish green, glossy.  Stems 5–8 cm, scarcely tomentose with whitish to reddish brown rhizoids.  Leaves erect or spreading, distal leaves with twisted apices when dry, slightly rugose, (3.5–)5–7(–8) × 1–1.5 mm, concave proximally, tubulose above, from an ovate-lanceolate base to a long or short subula, broadly acute, some leaves short, ovate, somewhat obtuse, forming julaceous regions, in the middle or basal part of the stems, margins not or slightly serrate in distal part, somewhat involute in the middle part; laminae 1-stratose; costa ending before the apex, 1/13–1/8 width of leaves at base, smooth or sometimes distal part with 2 weakly serrated ridges on abaxial surface, row of guide cells, 2 stereid bands, adaxial and abaxial epidermal layers of cells not differentiated or sometimes a few cells in the abaxial layer differentiated; cell walls between lamina cells not bulging; leaf cells smooth; alar cells 2-stratose, differentiated, not extending to costa; proximal laminal cells elongate-sinuose, pitted, (42–)75–87(–107) × (7–)8–10(–16) µm; distal laminal cells short, sinuose, pitted, (16–)30–65(–79) × (7–)9–13(–16) µm.  Sexual condition pseudomonoicous; dwarf males on rhizoids of female plants; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta solitary, yellow, yellowish brown or reddish yellow, 2–4 cm.  Capsule arcuate, inclined, yellow to yellowish brown, 2–3.5 mm, smooth, ± furrowed when dry; operculum 1.5–2 mm.  Spores 14–24 µm.

Capsules mature in spring.  Primarily in hummocks in ombrotrophic and oligotrophic peatlands; 10–1100 m; B.C., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., swYukon; s Alaska; nw Europe.

This species is apparently closely related to Dicranum bonjeanii.  It is best distinguished by the subulate leaves with twisted apices when dry, the usual occurrence of julaceous stem portions with broad, short, concave, and somewhat obtuse leaves in contrast to the longer, narrower, subulate, and acute leaves of the other stem portions. Its occurrence only in hummocks in peatlands also is a clue to its identity.  The plants rarely produce sporophytes but in any event they cannot be distinguished from those of the other species in section Dicranum.  The species probably occurs in peatlands in northeastern United States and it should be looked for in that region.

6.   Dicranum majus   Turner, Muscol. Hibern. Spic. 58.  1804

Plants in loose tufts, green to light green, glossy to somewhat dull.  Stems 3–16 cm, naked or with a few whitish rhizoids, rarely moderately tomentose, rhizoids(micronemata) in rows above each leaf.  Leaves somewhat sparse, falcate-secund or erect-patent, flexuose or straight, little changed when dry, usually smooth, (6–)8–11.5(–15) × 1–2 mm, concave proximally, tubulose above, from a lanceolate to ovate-lanceolate base, gradually narrowed to a long, falcate-secund or straight, acute apex, margins serrate in distal 1/2, sometimes slightly serrulate above to almost entire; laminae 1-stratose or with few 2-stratose regions on or near the margins; costa percurrent to shortly excurrent, 1/12–1/7 width of leaves at base, toothed distally or serrulate to nearly smooth on abaxial surface, with a double row of guide cells that is sometimes interrupted, 2 stereid bands extending to apex, adaxial epidermal layer of cells with some cells differentiated, abaxial layer completely differentiated; cell walls between lamina cells not bulging; leaf cells smooth or abaxially prorate or toothed above; alar cells 2-stratose or multistratose, well differentiated, not extending to costa; proximal laminal cells elongate, pitted, (42–)71–112(–140) × (5–)9–10(–15) µm; distal laminal cells shorter, linear to oval, pitted, (42–)47–61(–99) × (7–)10–11(–17) µm.  Sexual condition pseudomonoicous; dwarf males among rhizoids of female plants; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta aggregate, 2–5 per perichaetium, rarely solitary, yellow to light brown, 2.5–5 cm.  Capsule arcuate, inclined to horizontal, dark brown or yellowish brown, 2–3.5 mm, smooth to faintly striate when dry; operculum 2–3 mm.  Spores 14–19 µm.

Varieties number worldwide? (2 in the flora): North America, Europe, Asia.

This is the only North American species of Dicranum with a double row of guide cells.  It is a distinctive species with oceanic tendencies and, in North America it commonly grows in northern coastal localities on both sides of the continent, occasionally occurring inland in very moist habitats.

1.   Leaves falcate-secund, 8–15 mm, margins serrate in distal 1/2; costa toothed distally on abaxial surface, with a double row of guide cells...................................
                                  6a.   Dicranum majus var. majus

1.   Leaves erect-patent, 6–8 mm, margins slightly serrulate above to almost entire; costa serrulate to nearly smooth distally on abaxial surface, with an interrupted double row of guide cells...........................
                      6b.   Dicranum majus var. orthophyllum

6a.    Dicranum majus   Turner var. majus

Plants in loose tufts, green to light green, glossy.  Leaves falcate-secund, flexuose, 8–11.5(–15) mm, margins serrate in distal 1/2; costa percurrent to shortly excurrent, toothed distally on abaxial surface, with a double row of guide cells.

Capsules mature in spring.  Humus, soil, soil over rocks, rotten wood in coniferous woods, bogs, and tundra; 0–1500 m; Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Yukon; Alaska, Maine, Mass., R.I., Wash.; Europe; Asia.

The var. majus is known by its glossy, long (8–15 mm), falcate-secund leaves with serrate margins in the distal half, by its costae with two rows of guide cells (seen in cross section), the abaxial surface toothed and not ridged distally, and by its aggregate setae (2–5 per perichaetium).

6b.    Dicranum majus var. orthophyllum   Milde, Bryol. Siles. 71.  1869

Plants in loose tufts, mostly light green, somewhat dull.  Leaves erect-patent, 6–8 mm, margins slightly serrulate distally to almost entire; costa serrulate to nearly smooth distally on abaxial surface, with an interrupted double row of guide cells.

Capsules mature in spring.  Humus, sand, and rock in the tundra; 40–1500 m; B.C., Man., N.W.T., Que., Yukon; Alaska; Europe.

This is an extremely weak Arctic variety that differs from the typical var. majus in only a few minor characters.  The plants immediately appear different because of the erect-patent, short leaves instead of the long, falcate-secund leaves of the typical var. majus.  More collections are needed from many Arctic localities to better understand this variety, which may only be an environmental form.  The Alaska record is from I. A. Worley & Z. Iwatsuki (1970).

7.   Dicranum rhabdocarpum   Sullivant, Mem. Amer. Acad. 4: 172.  1849

Orthodicranum rhabdocarpum (Sullivant) Holzinger

Plants in dense tufts, green to yellowish green or brownish, ± glossy.  Stems 2–8 cm, tomentose with reddish brown rhizoids.  Leaves straight or nearly so, spreading, little changed when dry, smooth, 3–5.5 × 0.6–1.2 mm, concave or tubulose proximally, tubulose to slightly keeled above; ovate-lanceolate, apex obtusely acute, margins serrate near apex; laminae 1-stratose; costa subpercurrent to percurrent, 1/10–1/8 width of leaves at base, smooth or weakly toothed on abaxial surface near apex, with a row of guide cells, 2 weak stereid bands, at least in basal part of leaf, adaxial and abaxial epidermal layers of cells not differentiated; cell walls between lamina cells not bulging; leaf cells smooth; alar cells 1- or 2-stratose in part, differentiated, not extending to costa; proximal laminal cells linear-rectangular, pitted, (45–)65–120(–150) × (13–)16–17(–19) µm; distal laminal cells shorter, narrow, pitted or with few pits, (20–)30–45(–60) × (5–)8–10(–13) µm.  Sexual condition dioicous; male plants about as large as the female or slightly smaller; interior perichaetial leaves ± abruptly acuminate, convolute-sheathing.  Seta solitary, rarely 2 per perichaetium, yellow to reddish brown, 1.5–3 cm.  Capsule erect, straight or nearly so, brown, 1.5–3.5 mm, furrowed when dry; operculum 1.6–2.8 mm.  Spores 13–19 µm.

Capsules mature in summer.  Soil, soil over rocks, peaty soil or rotten wood; 1600–3300 m; Ariz., Colo., N.Mex., Wyo.; Mexico (Chihuahua, Tamaulipas); West Indies (Dominican Republic); Central America (Guatemala).

This is easily recognized species that occurs in the flora area only in the Rocky Mountains and the mountains of Arizona.  It is the only species in the section Dicranum that has erect, straight to weakly arcuate capsules.  Other important distinguishing features are the ovate-lanceolate, straight, obtusely acute, 1-stratose leaves with alar cells 1- or 2-stratose in part and the subpercurrent to percurrent costae that are smooth or weakly toothed on the abaxial surface near the leaf apex.  Dicranum rhabdocarpum has been placed in the segregate genus Orthodicranum by J. M. Holzinger (1925) and other bryologists mainly because of its straight and erect capsules.  However, it differs from taxa commonly placed in that genus, i.e., D. flagellare, D. fulvum, D. montanum, D. strictum and D. viride, by the elongate, pitted cells and the alar cells that are sometimes 2-stratose.

8.   Dicranum undulatum   Bridel, J. f. Bot.  1800, 1(2): 294.  1801, not G. F. Weber & C. Mohr  1803

Dicranum bergeri Blandow

Plants in dense compact tufts, green to yellowish brown, shiny, rarely somewhat dull.  Stems 3–8(–17) cm, densely tomentose with reddish brown rhizoids.  Leaves erect-appressed or sometimes slightly falcate or flexuose, somewhat contorted when dry, apex often twisted, weakly to strongly undulate, (4.5–)5–7.5(–11) × 0.7–1.2 mm, concave proximally, keeled above, lanceolate to oblong-lanceolate, broadly acute, rarely narrowly acute, margins plane, sometimes involute at base, broadly recurved at apex, entire proximally, serrulate to serrate in distal 1/2; laminae 1-stratose, sometimes with a few 2-stratose regions; costa strong, ending before apex, sometimes nearly percurrent, 1/6–1/3 width of leaves at base, smooth to serrulate above on abaxial surface, with a row of guide cells, 2 stereid bands extending to apex, adaxial epidermal layer of cells not differentiated, abaxial layer diffferentiated; cell walls between lamina cells weakly to strongly bulging abaxially and adaxially; leaf cells smooth to ± papillose near apex on abaxial surface; alar cells 2-stratose, differentiated, not extending to costa; proximal laminal cells elongate, incrassate, pitted, (22–)38–61(–79) × (2)4–6(8) µm; median laminal cells rectangular, pitted; distal laminal cells short-rectangular to irregularly angled, not pitted, (7–)11–14(–28) × (4–)11–12(–17) µm.  Sexual condition pseudomonoicous; dwarf males on stem rhizoids of female plants; interior perichaetial leaves abruptly acuminate, convolute-sheathing.  Seta solitary, yellow to brown, 2–4 cm.  Capsule arcuate, inclined, yellow to yellowish brown or reddish brown, 2–2.8 mm, furrowed when dry, ± contracted below mouth; operculum 2–3 mm.  Spores 14–28 µm.

Capsules mature in spring.  Usually in wet habitats, especially bogs in Sphagnum hummocks, fens, swamps, marshes, margins of lakes; sometimes on or among rocks, rock outcrops and cliffs; occasionally in mesic woods or on dry bluffs on soil, rotten wood, or humus; 10–2200 m; Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Alaska, Calif., Colo., Conn., Ind., Maine, Mass., Mich., Minn., Mont., N.H., N.J., N.Y., N.C., Ohio, Pa., S.Dak., Vt., Wash., W.Va., Wis.; Europe; Asia.

This is a boreal species that is distinctive because of the yellowish green or yellowish brown, shiny, erect-appressed, lanceolate to oblong-lanceolate, undulate, keeled leaves, the leaf margins that are serrulate to serrate, and broadly recurved in the distal half, the leaf apices that are usually broadly acute, rarely narrowly acute, and the costae that are mostly subpercurrent or sometimes percurrent, smooth to serrulate above on abaxial surface.  When the leaf apices are narrow, ± acute, and the costa percurrent, as some D. undulatum plants are on rare occasion, the species when sterile can be confused with D. ontariense.  Dicranum undulatum has shiny leaves with twisted apices when dry compared to the more dull leaves that are variously contorted in D. ontariense.  When sporophytes are present the aggregate setae (2–5 per perichaetium) of D. ontariense will immediately distinguish it from D. undulatum which has solitary setae. 

This species recently has been introduced on the University of California Berkeley Campus in a lawn-landscaping area; this is the only California locality where it has been found.  The plants are sterile but appear morphologically similar to those growing in native habitats in other parts of North America.  The Colorado record is from R. R. Ireland in E. Lawton (1971).

9.   Dicranum ontariense   W. L. Peterson, Canad. J. Bot. 55: 988.  1977    E

Dicranum drummondii Sullivant not J. K. A. Müller

Plants in loose tufts, dark to light green, dull.  Stems 3–8 cm, densely tomentose below with reddish brown rhizoids. Leaves falcate-secund, flexuose, contorted when dry, slightly undulate, (5–)6.5–9(–10) mm × 1–1.5 mm, concave below, keeled above, from a lanceolate base to a long-acuminate apex, margins plane, strongly serrate above; laminae 1-stratose, rarely with 2-stratose regions on margins or near costa; costa percurrent to slightly excurrent, 1/6–1/5 width of leaves at base, papillose to spinose above on numerous, low abaxial ridges, with a row of guide cells, 2 thick, well-developed stereid bands above and below extending to apex, adaxial epidermal layer of cells not differentiated, abaxial layer differentiated; cell walls between lamina cells not bulging or weakly bulging; leaf cells prorate on abaxial surface, sometimes papillose adaxially; alar cells 2-stratose, rarely 3-stratose in parts, differentiated, not extending to costa; proximal laminal cells rectangular, pitted, (22–)40–64(–126) × (2–)7–8(–10) µm; distal laminal cells short-rectangular to rectangular, not pitted, ± in longitudinal rows, marginal cells usually more elongate, some distal cells with long tooth-like projections, scattered on abaxial surface, (7–)12–18(–42) × (5–)8–12(–16) µm.  Sexual condition pseudomonoicous; dwarf males on stem rhizoids of female plants; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta often aggregate 2–5 per perichaetium, sometimes solitary, yellow, brown, or reddish yellow, 2–3.5 cm.  Capsule arcuate, inclined to horizontal, yellow to light brown, 2–3 mm, furrowed when dry; operculum 1.5–3 mm.  Spores 9–20 µm.

Capsules mature in spring.  Humus, soil, or soil over rocks, rarely rotten logs or stumps, usually in mesic to dry coniferous woods, sometimes swamps and bogs; 60–1200 m; Alta., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Sask.; Maine, Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., Tenn., W.Va., Wis., Wyo.

This North American endemic species was previously mistaken for Dicranum drummondii J. K. A. Müller, a predominately Eurasian species which was unknown on this continent until it was discovered just recently on the Aleutians Islands.  W. Peterson (1977) clarified the taxonomic position of D. ontariense, while P. Isoviita (1977) amplified on the complex nomenclatural details of why it must be recognized as a species distinct from D. drummondii.  The main distinguishing features of D. ontariense are the dark to light green, dull, falcate-secund, flexuose tipped, slightly undulate leaves, contorted when dry, keeled above from a lanceolate base to a long-acumination, the leaf apices papillose to spinose above on abaxial surface, the laminae 1-stratose except for occasional 2-stratose regions on margins, the leaf margins plane, strongly serrate above, and the usually multiple sporophytes, 2–5 per perichaetium.

This species is sometimes confused with an environmental form of D. undulatum that has nearly percurrent costae and more-or-less acute apices.  The aggregate setae of D. ontariense will immediately distinguish it from that form which has solitary setae.  The dull leaves that are contorted when dry, and the leaf apices that are long-acuminate, abundantly spinose on the abaxial surface, are other superficial features to distinguish it from D. undulatum, which has shiny, usually broadly acute, smooth or serrulate leaf apices.  Also, on occasion, D. ontariense can be confused with large forms of D. condensatum when sterile.  The thin-walled, short-rectangular to quadrate distal-median cells in more or less regular rows of the former will distinguish it from the latter, which has irregularly shaped cells that are thick-walled and usually not in well defined rows.  When fruiting, the aggregate setae on some of the plants of D. ontariense will immediately distinguish it from D. condensatum, which has solitary setae.

The Alberta record is from W. Peterson (1979).

10.   Dicranum drummondii   J .K .A. Müller, Syn. 1: 356.  1848

Dicranum elatum Lindberg; D. robustum Bruch, Schimper & W. Gümbel

Plants in loose tufts, yellowish green to yellowish brown below, shiny to dull.  Stems 5–11 cm, densely tomentose below with reddish brown rhizoids.  Leaves erect and compressed to somewhat flexuose, curled to flexuose at apices when dry, undulate or rugose, (7–) 8–10 (–12) mm × 1.5–2 mm, concave below, keeled above, from an oblong-ovate base to a long-acuminate apex, margins incurved to tubulose below, plane and strongly serrate above; laminae 1-stratose below, sometimes a few scattered 2-stratose regions above; costa percurrent to shortly excurrent, 1/6 –1/10 width of leaves at base, papillose to serrate above on abaxial surface, without lamellae, with a row of guide cells, 2 stereid bands above and below extending to apex, adaxial epidermal layer of cells with a few cells slightly larger than the stereids differentiated, abaxial layer completely differentiated with cells slightly larger than the stereids; cell walls between lamina cells not bulging; leaf cells smooth or a few cells prorate on abaxial surface; alar cells 2-stratose, differentiated, extending to costa; proximal laminal cells irregularly rectangular, often narrowed at ends, narrow and elongate on margins, pitted, (67–) 82–98 (–112) × (5–) 6–8 (–9) µm; distal laminal cells round, oblong, somewhat rectangular, with a few pits (9–) 13–19 (–30) × (3–) 6–9 (–12) µm.  Sterile, no sex organs seen.  [Sexual condition pseudomonoicous, male plants on leaves of female plants. Interior perichaetial leaves abruptly subulate, convolute-sheathing.  Seta 2–3 per perichaetium, sometimes solitary, yellowish, 3–5 cm.  Capsule arcuate, inclined to horizontal, yellowish brown, 2.5–3.5 mm, striate when dry; operculum 2.3–3 mm.  Spores 14–18 µm.

?Mature capusules unknown.  Large clones in mesic mire; Alaska; Europe; Asia (China, Japan, Korea, Russia).

Dicranum drummondii, primarily an Eurasian species, was for years confused with the endemic North American species, Dicranum ontariense W. L. Peterson (see discussion under D.ontariense).  It was only recently (August 2000) that W. B. Schofield, S. S. Talbot and S. L. Talbot made the first and only collection of the species, which was sterile, from Attu Island in the Aleutian Islands, Alaska.  The species is best recognized by its robust size, stems 5–11 cm, its leaves yellowish green to yellowish brown, undulate or rugose, erect and compressed, becoming flexuose at the tips when dry, concave below and keeled above, with an oblong-ovate base, becoming long-acuminate at apex, margins strongly toothed above, and costa percurrent to shortly excurrent, without lamellae.  Microscopically, distinguishing characters are the leaves in the distal part with round, oblong, somewhat rectangular cells with few pits, cells smooth or prorate on abaxial surface, in cross section the lamina with a few scattered 2-stratose cells, cells walls between the lamina cells not bulging, and costa with a few cells differentiated on the adaxial epidermal surface.

11.   Dicranum condensatum   Hedwig, Spec. Musc. 139.  1801, not plate 34    E

Dicranum sabuletorum Renauld & Cardot

Plants in ± dense tufts, light green to yellowish brown, dull.  Stems 1–9 cm, densely tomentose below with reddish brown rhizoids.  Leaves erect-spreading, flexuose, ± curled at the tips when dry, slightly undulate or rugose, (2–)3.5–4.5(–7) × 0.5–1 mm, concave below, strongly keeled above, oblong-lanceolate, with a broad lanceolate base gradually narrowing to a short-acuminate apex, margins serrulate in distal 1/2, involute in central part; laminae 1-stratose, with a few 2-stratose regions; costa percurrent to shortly excurrent, 1/10–1/5 width of leaves at base, strong, smooth or papillose to toothed above on abaxial surface, abaxial ridges lacking, with a row of guide cells, 2 thick stereid bands extending well into the apex, adaxial epidermal layer of cells not differentiated, abaxial layer differentiated; cell walls between lamina cells strongly bulging; leaf cells papillose above on abaxial surface, sometimes nearly smooth; alar cells 2-stratose, differentiated, not extending to costa; proximal laminal cells elongate, pitted, (25–)41–56(–112) × (5–)6–7(–10) µm, abruptly shorter towards the apex; distal laminal cells quadrate, irregularly angled, rounded or rectangular, not or indistinctly pitted, cell walls unequally thickened, (5–)7–8(–20) × (5)7–8(12) µm.  Sexual condition pseudomonoicous; dwarf males on stem rhizoids of female plants; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary, rarely 2 per perichaetium, yellowish, 1–4 cm.  Capsule arcuate, inclined to horizontal, yellowish brown, 1.5–3 mm, furrowed when dry, slightly contracted below the mouth; operculum 1.5–2.5 mm.  Spores 19–26 µm.

Capsules mature in spring.  Exposed sandy soil, often in pine woods, frequently over sandstone and limestone; 0–700 m; N.B., N.S, Que.; Ala., Ark., Del., D.C., Fla., Ga., Ill., Kans., Ky., La., Maine, Md., Mass., Mich., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va.

This is a common species endemic to eastern North America.  It is known in the field by its occurrence on sandy soil, by its light green to yellowish brown, dull plants in compact, dense tufts, by its erect-spreading, oblong-lanceolate leaves, narrowing to a short-acuminate apex, keeled above, somewhat undulate or rugose, curled at tips when dry and by its solitary setae with an arcuate, inclined to horizontal capsule.  The papillose leaf cells with strongly bulging walls between the cells and the irregularly angled median and distal cells with nonpitted walls are distinctive microscopic characters. 

Dicranum spurium is the species most commonly confused with D. condensatum. Both species occur on sandy soil with their ranges overlapping.  The former occurs farther northward, where it is found in Newfoundland, while the latter occurs farther to the south, where it extends its range to the tip of Florida.  Dicranum spurium has broader leaves, the broadest point near the leaf middle rather than near the base like D. condensatum, and leaves that are tubulose above (most noticeable when wet) rather than keeled.  Rarely, D. condensatum can be mistaken for D. ontariense as discussed under that species.

12.   Dicranum spurium   Hedwig, Spec. Musc. 141.  1801

Plants in loose tufts, green to yellowish green or yellowish brown, dull.  Stems 2–11 cm, densely tomentose below with reddish brown rhizoids, interruptedly foliate, the leaves crowded in some parts forming swollen, globose regions.  Leaves erect-spreading, arched and loosely imbricate with contorted apices when dry, ± undulate to rugose, (2.5–)5–6.5(–9) × 1–1.7 mm, concave below, tubulose above, acute, ovate at base, widest point at or somewhat below middle, margins serrulate to serrate in distal 1/2, plane to involute; laminae 1-stratose or with 2-stratose regions near costa and on margins; costa percurrent to shortly excurrent, 1/8–1/4 width of leaves at base, serrulate or toothed above on abaxial surface, abaxial ridges lacking, with a row of guide cells, 2 stereid bands extending to apex, adaxial epidermal layer of cells not differentiated, abaxial layer differentiated; cell walls between lamina cells weakly to strongly bulging; leaf cells strongly papillose above on abaxial surface, sometimes a few papillae on adaxial surface; alar cells 2-stratose, distinctly differentiated, not extending to costa; proximal laminal cells elongate, pitted, (30–)49–68(–101) × (5)10–11(15) µm, abruptly shorter in distal 1/2 of leaf; distal laminal cells short, not or indistinctly pitted, cell walls irregularly thickened, (7–)11–12(–23) × (5–)7–13(–20) µm.  Sexual condition pseudomonoicous; dwarf males on rhizoids of female plants; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary, reddish yellow or brown, 1–3 cm.  Capsule arcuate, inclined to horizontal, yellowish brown to brown, 1.5–2.5 mm, contracted below mouth and furrowed when dry; operculum 1.5–2.5 mm.  Spores 16–24 µm.

Capsules mature in spring.  Sandy soils, decayed logs, acidic rock, humus over exposed bluffs or outcrops, in pine woods, sometimes bogs; 0–1400 m; Nfld. and Labr., N.S., Ont., P.E.I., Que.; Ark., Conn., Ga., Ill., Ky., Maine, Mass., Md., Mich., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., Tenn., Vt., Va., W.Va.; Europe.

This species is easily recognized by the turgid aspect of the plants with arched, imbricate leaves and with interruptedly foliate stems, i.e., some regions that appear swollen or globose as a result of several growth periods.  It is only likely to be confused with Dicranum condensatum (see discussion under that species).

13.   Dicranum brevifolium   (Lindberg) Lindberg, Musci Scand. 24.  1879

Dicranum muehlenbeckii var. brevifolium Lindberg, Bot. Not. 1865: 80.  1865

Plants in dense tufts, light to dark green, dark brown or sometimes nearly black, dull.  Stems 2–8 cm, densely tomentose with brown to orange rhizoids nearly to stem apex.  Leaves falcate-secund to erect-spreading, often at wide angles from stems, strongly crisped when dry, often with a few undulations in distal 1/2, (3–)5.5–6.5(–8.5) × 0.4–0.8 mm, concave below, keeled above, lanceolate, acute, margins entire below, serrulate above, incurved in middle of leaf; laminae 1-stratose or with 2-stratose regions in distal 1/2 of leaf, especially on margins, sometimes with entire laminae 2-stratose, rarely margins 3-stratose; costa percurrent or shortly excurrent, 1/6–1/4 width of leaves at base, very prominent and rounded on abaxial surface, smooth or slightly rough above on abaxial surface, abaxial ridges lacking, shaped like a pair of tongs, with 1 row of guide cells, 2 well-developed and thick stereid bands extending to the apex, adaxial epidermal layer of cells not differentiated, abaxial layer differentiated; cell walls between lamina cells strongly bulging; leaf cells smooth to papillose above on abaxial surface; alar cells 2-stratose, differentiated, sometimes extending to costa; proximal laminal cells elongate-rectangular, pitted or not pitted, (15–)31–46(–75) × (5–)7–9(–12) µm; distal laminal cells short, irregularly quadrate-rectangular, not pitted, (5–)7–14(–37) × (4)8–9(13) µm.  Sexual condition pseudomonoicous; dwarf males on stem rhizoids of female plants; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary, yellowish to brown, 1.3–3.5 cm.  Capsule arcuate, inclined to horizontal, yellowish brown to dark brown, long-cylindric, 2–4 mm, not or slightly strumose, striate to furrowed when dry; operculum 1–2.5 mm.  Spores 14–30 µm.

Capsules mature in summer.  Humus or soil over rocks, rarely rotted wood, exposed to protected bluffs or cliffs, 70–3700 m; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo., Mich., Mont., N.Mex., S.Dak.; Europe; Asia.

The distinctive leaves are 4–8 mm, acute, often weakly undulate in the distal part, crisped when dry, standing out from the stems often at wide angles, concave below, keeled above, the laminae are often 2-stratose above, especially on margins and near costa, sometimes entirely 2-stratose with 3-stratose margins (sometimes apparent on plants at relatively high altitudes in the mountains in Alberta) and the costa is excurrent, very prominent and conspicuously rounded, especially noticeable below the leaf middle.  The leaves in cross section are very distinctive, being shaped like a pair of tongs; abaxial epidermal layer of costal cells is differentiated but no adaxial epidermal layer cells are enlarged, and the cell walls between the lamina cells are almost always strongly bulging.  Dicranum brevifolium has commonly been confused with three other species, namely D. muehlenbeckii, D. acutifolium and D. fuscescens.  Dicranum muehlenbeckii has only 1-stratose leaf laminae and the costae are much less prominent on the abaxial leaf surface than those of D. brevifolium.  A cross section of the distal half of the leaves of D. muehlenbeckii shows a tubular outline with the cell walls between the lamina cells smooth and adaxial epidermal layer of costal cells differentiated, while the leaves of D. brevifolium are tong-shaped in outline with the cell walls between lamina cells strongly bulging and the adaxial epidermal layer of costal cells undifferentiated.  Dicranum acutifolium differs from D. brevifolium by its erect-spreading to slightly curled leaves when dry, instead of crisped leaves standing out from the stems at wide angles, its costae that are usually moderately distinct and sometimes nearly flat on the abaxial surface, instead of being prominent and conspicuously rounded, its V-shaped leaves in cross section, instead of tong-shaped leaves, and its shorter capsules, 2–2.5 mm, compared to 3–4 mm.  Dicranum fuscescens differs from D. brevifolium by its much less prominent costae on the abaxial leaf surface, by its V-shaped leaves in cross section, instead of tong-shaped leaves, and by its weakly bulging cell walls as seen in cross section.

The 2- or occasionally 3-stratose leaf laminae are unusual in the genus Dicranum.  The only other species in North America with laminae often completely 2-stratose in the distal half is D. fulvum. No 3-stratose leaf laminae have been seen in that species, however. A recently described species in the section Dicranum, D. crassifolium C. Sérgio, R. Ochyra & A. Séneca (1995), from Portugal, Spain, and Italy, has 2–3-stratose leaves.  It is very unusual for a species in the type section to have anything but 1-stratose leaves.

14.   Dicranum acutifolium   (Lindberg & Arnell) C. E. O. Jensen in A. H. Weimarck, Foert. Skand. Vaext. Moss. 2: 18.  1937

Dicranum bergeri var. acutifolium Lindberg & Arnell, K. Svensk. Vet. Ak. Handl. 23(10): 79.  1890

Plants in dense to loose tufts, light green to light brown, dull.  Stems 1.5–7 cm, generally branched above, somewhat tomentose with reddish brown rhizoids.  Leaves erect-spreading, slightly curled to ± straight when dry, usually with a few undulations in distal part, (3.5–)5–8(–10) mm × 0.5–1 mm, concave below, keeled above, sometimes margins ± involute, lanceolate, narrowly acute to acuminate, margins serrulate to serrate above; laminae 1-stratose or with few 2-stratose regions on or near distal margins; costa percurrent to shortly excurrent, 1/6–1/4 width of leaves at base, smooth to slightly papillose above on abaxial surface, abaxial ridges lacking, with a row of guide cells, 2 stereid bands extending to the apex, adaxial epidermal layer of cells not differentiated, abaxial layer differentiated; cell walls between lamina cells not or slightly bulging; leaf cells smooth to weakly papillose above on abaxial surface; alar cells 2-stratose, differentiated, often extending to costa; proximal laminal cells linear-rectangular, pitted, (22–)41–60(–90) × (5–)6–8(–12) µm; distal laminal cells short-rectangular, irregularly angled or rounded, not pitted, (7–)12–20(–32) × (4–)8–9(–14) µm.  Sexual condition pseudomonoicous; dwarf males on stem rhizoids of female plants; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary, yellow to reddish yellow, 1.2–2.5 cm.  Capsule arcuate, inclined to horizontal, brown to reddish brown, 2–2.7 mm, furrowed when dry, rarely slightly strumose; operculum 1.5–2.5 mm.  Spores 14–28 µm.

Capsules mature in summer.  Somewhat calcareous soils, boulders, rock outcrops and cliff ledges, sometimes humus, rarely rotten logs; 700–2500 m; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo., Maine, Mont., N.H., N.Y., N. Mex., Wyo.; Europe; Asia.

This Arctic-alpine species is recognized by its erect-spreading leaves, slightly curled when dry, keeled and often weakly undulate above, lanceolate, narrowly acute to acuminate, by its percurrent to shortly excurrent costae, smooth to slightly papillose above, and by its leaf cross section that shows only the abaxial row of cells differentiated, a few 2-stratose marginal cells and the cell walls between lamina cells smooth to slightly bulging.  Dicranum acutifolium has often been confused with D. fuscescens but the latter species has a longer, rougher subula that in leaf cross section in the distal half reveals very large and obvious papillae, compared to the smaller and less distinct ones in the former, and margins that are almost completely 2-stratose, while those of D. acutifolium are mostly 1-stratose.  It has also been confused with D. brevifolium and for distinctions see discussion under that species.

The Colorado record is from W. A. Weber (1973).  The New York, New Mexico, and Wyoming records are from W. Peterson (1979).

15.   Dicranum fuscescens   Turner, Muscol. Hibern. Spic. 60.  1804

Dicranum fuscescens var. congestum (Bridel) Husnot; D. sulcatum Kindberg

Plants light green to dark brownish green, dull, in loose tufts.  Stems 1–6(–18) cm, tomentose to scarcely tomentose with white or reddish brown rhizoids.  Leaves falcate-secund, often strongly so, sometimes somewhat sparse, distal leaves curled, proximal leaves with flexuose apices, slightly to strongly curled and crisped when dry, smooth, (3–)4–7(–10) × 0.6–1 mm, concave below, keeled above, from a lanceolate base to a gradually narrowed, fine, keeled subula, margins entire proximally, serrulate to strongly serrate in distal 1/2, sometimes nearly entire throughout; laminae 1-stratose and usually 2-stratose above on one or both margins, rarely some 2-stratose regions near costa; costa excurrent, 1/6–1/4 width of leaves at base, strong, terete, papillose to spinose distally on abaxial surface, occasionally almost smooth, sometimes extending to costa, abaxial ridges lacking, with a row of guide cells, 2 well-developed stereid bands extending to distal part of leaf, adaxial epidermal layer of cells not differentiated, abaxial epidermal layer differentiated; cell walls between lamina cells slightly bulging; leaf cells smooth to slightly papillose below on abaxial surface, papillose to spinose prorate above on abaxial surface; alar cells 2-stratose, strongly differentiated, sometimes extending to costa; proximal laminal cells elongate, pitted, (19–)43–62(–93) × (2–)6–8(–12) µm; distal laminal cells irregularly rounded, elliptic, short-rectangular to quadrate, not pitted, (7–)9–23(–36) × (4–)8–12(–14) µm.  Sexual condition dioicous; male plants as large as females, growing intermixed or in separate patches; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary, yellow, reddish yellow, or brown, 1–3.5 cm.  Capsule arcuate, inclined to horizontal, dark brown to reddish brown, 1–3 mm, strumose, strongly furrowed when dry, somewhat contracted below mouth; operculum 1–2 mm.  Spores 14–24 µm.

Varieties ?number worldwide (2 in the flora): North America, Europe, Asia.

l.    Plants small, stems 1–6 (–10) cm, usually densely foliate; leaf margins serrulate to strongly serrate in distal 1/2; costa papillose to spinose distally on abaxial surface; distal laminal cells short-rectangular to quadrate, mostly 18–23 μm; seta mostly shorter than2.5 cm....................................................................
                  15a.   Dicranum fuscescens var. fuscescens

1.   Plants large, stems 8–18 cm, sparsely foliate; leaf margins nearly entire; costa almost smooth on abaxial surface; distal laminal cells irregularly rounded, elliptic or short- rectangular, mostly 9-19 μm; seta usually 2.5 cm or longer............................................................
                    15b.   Dicranum fuscescens var. flexicaule

15a.    Dicranum fuscescens   Turner var. fuscescens

Plants in loose tufts.  Stems 1–6 (–10) cm, tomentose with white or reddish brown rhizoids.  Leaves falcate-secund, usually densely foliate, margins serrulate to strongly serrate in distal 1/2; costa papillose to spinose distally on adaxial surface; proximal leaf cells elongate, pitted, (25–)43–62(–93) × (2–)6–8(–12) μm; distal laminal cells short-rectangular to quadrate, not pitted, (8–)18–23(–31) × (5–)8–12(–14) μm.  Seta 1–3.5 cm.

Capsules mature in spring.  Coniferous or deciduous tree trunks and bases of trees, rotten logs, stumps, soil, boulders, rock outcrops, cliff shelves, and humus in woodlands, or sometimes bogs; 10–2300 m; Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Alaska, Calif., Colo., Ga., Idaho, Ky., Maine, Mass., Mich., Minn., Mont., N.H., N.Mex., N.Y., N.C., Ohio, Oreg., Pa., S.Dak., Tenn., Vt., Va., Wash., W.Va., Wis., Wyo.; Europe; Asia.

The var. fuscescens is highly variable but is best known by the loose tufts of green to brownish green, dull plants, the slender, falcate-secund leaves ending in a slender, keeled subula, slightly to strongly crisped when dry, the strongly serrated, often 2-stratose distal leaf margins, the excurrent costa that is conspicously rough above with papillae and spines on the abaxial surface, the nonpitted, short-rectangular, quadrate or irregularly angled distal leaf cells, and the solitary, often strumose, capsules that are inclined to horizontal.

Some plants of D. fuscescens, especially those in the northern part of Canada, may be confused with D. acutifolium.  The latter, however, usually has a few undulations on the leaves and the leaf cross section often reveals larger, more rounded bulging cell walls between the lamina cells and fewer 2-stratose regions on the margins than D. fuscescens. 

Dicranum sulcatum Kindberg, considered a synonym here and by R. S. Williams (1913), has been recognized by W. Peterson (1979) as a distinct species.  The diagnostic features are duller color due to a greater degree of papillosity, long-excurrent costa, wider costa at mid-leaf, and presence of more rows of stereid cells, 3–5 rows compared to 2–3 rows in D. fuscescens.  Dicranum sulcatum is reported to occur usually on living coniferous trees in the Pacific Northwest, from southern Alaska south to central California, inland to northern Idaho and northwestern Montana.  All of the diagnostic characters are too variable to be important in maintaining this species.  Furthermore, they are all quantitative characters, which makes it difficult to establish a distinct species without at least one good qualitative character.  Further studies could help to establish it as a variety.

The Kentucky record is from J. A. Snider et al. (1988), the Massachussetts record is from F. J. Hilferty (1960), and Ohio record is from J. A. Snider and B. K. Andreas (1996).

15b.    Dicranum fuscescens var. flexicaule   (Bridel) Wilson, Bryol. Brit. 77.  1855

Dicranum flexicaule Bridel, Bryol. Univ. 1: 421.  1826

Plants in loose tufts.  Stems 8-18 cm, scarcely tomentose.  Leaves strongly falcate-secund, somewhat sparse, margins nearly entire; costa almost smooth on abaxial surface; proximal laminal cells elongate, (19–)42–54(–84) × (5–)7–9(–12) µm; distal laminal cells irregularly rounded, elliptic or short-rectangular, (7–)9–19(–36) × (4–)8–9(–13) µm.  Seta 2.5–3.5 cm.

Capsules mature in summer.  Moist humus banks, humus on coniferous forest floors, and bogs on small conifers (often black spruce); 900–1300 m; B.C., N.W.T., Que., Yukon; Europe.

This is an Arctic-alpine variety that needs further collecting and study to determine its taxonomic status. J. Kucyniak (D. Löve et al. 1958) called attention to it in the Quebec bryoflora (G. Bellolio-Trucco and R. R. Ireland 1990) and, many European bryologists recognize it as a form (W. Mönkemeyer 1927), variety (J. Podpêra 1954; L. I. Savich-Lyubitskaya and Z. N. Smirnova 1970; V. M. Melnichuk 1970) or species (E. Nyholm 1986).  It is immediately noticed because of the large size of the plants whose stems are up to 18 cm, sparsely foliated with strongly falcate-secund leaves, and the long seta, 2.5–3.5 cm.  It is further recognized microscopically by the irregular shape of the distal leaf cells, the nearly entire leaf margins, and the costa almost smooth on the abaxial surface.

16.   Dicranum pallidisetum   (J. W. Bailey) Ireland, Bryologist 68: 446.  1965

Dicranum fuscescens f. pallidiseta J. W. Bailey in Holzinger, Musci Acro. Bor.-Amer. & Eur. 653.  1929

Plants in loose tufts, dark green to yellowish green, dull to glossy.  Stems 1–6 cm, tomentose with white or reddish brown rhizoids.  Leaves often secund, straight or nearly so, often crisped when dry, smooth, 4–8 × 0.5–1 mm, lanceolate, acute, tubulose to apex, margins entire below, serrulate ot serrate near apex; laminae 1-stratose or sometimes 2-stratose on distal margins; costa excurrent, 1/5–1/3 width of leaves at base, abaxially papillose or toothed from leaf middle to apex, abaxial ridges lacking. with a row of guide cells, stereid bands often present and well developed in proximal part of leaf, lacking in distal 1/4–1/3 of leaf, cells above and below guide cells large and thin walled; cell walls between lamina cells not or slightly bulging; leaf cells smooth or often strongly papillose in distal 1/2 of leaf; alar cells 2-stratose, differentiated, often extending to costa, abaxial ridges lacking; proximal laminal cells linear to rectangular, with or without pits, (26–)58–95(–130) × (10–)12–14(–16) µm; distal laminal cells quadrate, rounded, irregularly angled or short-rectangular, not pitted, (10–)15–26(–38) × (8–)9–11(–12) $$$m.  Sexual condition dioicous; male plants as large as female plants; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary or sometimes 2, rarely 3 per perichaetium, yellow, rarely reddish yellow or brown with age, 1–2.5 cm.  Capsule arcuate, inclined, often with a small struma, yellow or yellowish brown, rarely reddish yellow or brown with age, 1.5–3.5 mm, strongly furrowed when dry, contracted below mouth; operculum 1.5–2.5 mm.  Spores 14–20 µm.

Capsules mature in summer.  Humus or soil over rocks, rarely rotting logs or decayed wood; 500–2000 m; Alta., B.C.; Alaska, Idaho, Mont., Oreg., Wash.

This is an endemic northwestern North American species that has often been confused with Dicranum fuscescens, being considered a form of it for many years (R. R. Ireland 1966).  Unlike that species, which often occurs at low altitudes below 800 m, D. pallidisetum occurs predominately at high elevations, 800–2000 m, rarely being found as low as 500 m. It is distinguished from D. fuscescens by its tubulose leaves, usually 1-stratose or rarely 2-stratose on the margins, by its costa cross section that shows no stereid bands in distal 1/3 of the leaf, and by its yellow or yellow-brown capsules that are sometimes 2–3 per perichaetium.  In contrast, D. fuscescens has leaves keeled above, usually 2-stratose on both margins, rarely 1-stratose on one margin, stereid bands present throughout the leaf and dark brown to reddish brown capsules that are solitary or rarely 2 per perichaetium.

17.   Dicranum spadiceum   J. E. Zetterstedt, K. Svensk. Ak. Handl. 5(10): 20.  1865

Dicranum angustum Lindberg; D. laevidens R. S. Williams

Plants in loose to dense tufts, green to yellowish green or brown, glossy.  Stems 2.5–7 cm, densely tomentose with reddish brown rhizoids.  Leaves straight, erect-spreading, little changed when dry, smooth, (4–)5.5–8(–9) × 0.5–1 mm, concave below, tubulose above, from a lanceolate base to a long-acuminate subula, apices acute or sometimes ± blunt, margins entire or slightly serrate in distal 1/3; laminae 1-stratose; costa percurrent to shortly excurrent, 1/10–1/6 width of leaves at base, smooth to slightly rough above on abaxial surface, abaxial ridges lacking, with a row of guide cells, 2 well-developed stereid bands extending almost to apex, abaxial epidermal layer of cells differentiated, rarely some cells in adaxial epidermal layer enlarged; cell walls between lamina cells not or slightly bulging; leaf cells smooth; alar cells 2-stratose, well differentiated, not extending to costa; proximal laminal cells elongate, pitted, (16–)36–62(–112) × (3–)7–8(–20) µm; distal laminal cells short-rectangular to irregularly angled, pitted, (9–)10–17(–31) × (3–)7–8(–18) µm.  Sexual condition pseudomonoicous; dwarf males on rhizoids of female plants; interior perichaetial leaves abruptly acuminate, convolute-sheathing.  Seta solitary, rarely 2 per perichaetium, yellow to reddish yellow, 2.5–3.5 cm.  Capsule arcuate, inclined, light to dark brown, 2–3.5 mm, furrowed when dry; operculum 1.5–2.8 mm.  Spores 14–22 µm.

Capsules mature in summer.  Fens, wet meadows, willow thickets, or humus or soil on or around rocks at lake margins, occasionally drier habitats, such as beach ridges; 10–2300 m; Greenland; Alta., B.C., Man., Nfld. and Labr., Nunavut, Ont., Que., Sask., Yukon; Alaska, Colo., Mont., Utah, Wyo.; Europe; Asia.

This is an Arctic-alpine species known principally by the 4–9 mm, straight, erect-spreading leaves, scarcely changed when dry, concave below, tubulose above, narrowed from a lanceolate base to a long-acuminate subula ending in an acute to ± blunt apex; the elongate, pitted cells throughout the leaf; and the costa that is smooth to somewhat rough above on the abaxial surface. 

Dicranum angustum Lindberg, often considered distinct because of its blunt leaf apices, is considered a synonym after examination of its type from Europe (see discussion by G. Bellolio-Trucco and R. R. Ireland 1990).

The Saskatoon record is from G. Bellolio-Trucco and R. R. Ireland (1990), the Colorado record is from W. Peterson (1979), Montana record is from S. Eversman and A. J. Sharp (1980), and the Utah record is from S. Flowers (1973).

18.   Dicranum muehlenbeckii   Bruch, Schimper & W. Gümbel, Bryol. Eur. 1: 142. 78.  1847 (fasc. 37-40. Mon. 38.30)

Plants in dense tufts, green to yellowish green, dull.  Stems 3–7 cm, densely tomentose with reddish brown rhizoids.  Leaves erect-spreading, strongly cirrate to crisped when dry, smooth, (4–)5–6.5(–8) × 0.5–1 mm, concave below, tubulose above, lanceolate, acute, margins entire below, slightly serrate to entire above; laminae 1-stratose; costa excurrent, 1/6–1/4 width of leaves at base, smooth or weakly toothed above on abaxial surface, abaxial ridges lacking, with a row of guide cells, 2 stereid bands extending to apex, adaxial and abaxial epidermal layers of cells differentiated; cell walls between lamina cells slightly bulging; leaf cells smooth to slightly rough above on abaxial surface; alar cells 2-stratose, differentiated, sometimes extending to costa; proximal laminal cells rectangular, pitted, (19–)37–55(–73) × (5–)9–12(–14) µm; distal laminal cells short, irregularly quadrate-rectangular, not pitted, (7–)11–12(–23) × (6–)8–9(–13) µm.  Sexual condition pseudomonoicous; dwarf males on stem rhizoids of female plants; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary, yellowish to yellowish brown, 1.3–3 cm.  Capsule arcuate and inclined to ± straight and nearly erect, yellowish brown, long-cylindric, 2–4 mm, smooth, striate when dry; operculum 1.5–2.5 mm.  Spores 14–24 µm.

Capsules mature in summer.  Humus and sandy soil on cliffs, bluffs, often over boulders and among rocks in open woods or exposed sites; 10–3100 m; Greenland; Alta, B.C., Man., N.B., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo., Mass., Mont., Nebr., N.J., N.Mex., N.Y., N.Dak., S.Dak., Vt., Wyo.; Europe; Asia.

This is a somewhat rare species throughout North America where it is often misidentified as other species of Dicranum.  There should be no reason for its misidentification if its important characters are utilized for recognition.  Smooth, erect-spreading leaves, cirrate to crisped when dry and tubulose above, smooth leaf cells, 1-stratose laminae, and cross section of the costa showing the abaxial and adaxial rows of cells differentiated, all combine to make the gametophytes different from all other North American species of the genus.  Sporophytes are rarely produced but the 2–4 mm, solitary, long-cylindric, slightly strumose capsules, which are suberect to slightly arcuate and weakly striate when dry, are distinctive.

19.   Dicranum elongatum   Schwägrichen, Spec. Musc. Suppl. 1(1): 171.  1811

Plants in compact tufts, yellowish green to light green, glossy.  Stems 2–10 cm, tomentose throughout with reddish brown rhizoids.  Leaves erect-spreading, erect-appressed to rarely spreading when dry, apex sometimes flexuose, smooth, (2.5–)3–4.5(–6) × 0.3–0.5 mm, from a lanceolate base to a long, fine, tubulose subula, apex usually acute, sometimes apical leaves of stems blunt, julaceous, margins entire, rarely slightly denticulate at apex; laminae 1-stratose; costa percurrent or shortly excurrent, 1/6–1/4 width of leaves at base, smooth or weakly rough above on abaxial surface, abaxial ridges lacking, with a row of guide cells, 2 stereid bands not extending to apex, adaxial and abaxial epidermal layers of cells usually not differentiated or sometimes a few cells in both layers enlarged; cell walls between lamina cells slightly bulging; leaf cells smooth; alar cells 1-stratose or 2-stratose, well differentiated, not extending to costa; proximal laminal cells usually elongate, pitted, (14–)24–36(–49) × (2–)4–6(–9) µm; distal laminal cells short-rectangular, quadrate, rounded, or sometimes irregularly shaped, incrassate, not pitted, (5–)12–17(–23) × (4–)6–8(–9) µm.  Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta  solitary, yellowish to yellowish brown or reddish yellow, 1.5–2 cm.  Capsule nearly straight and erect to slightly arcuate, yellowish brown, 1.2–1.8 mm, striate when dry; operculum 1.2–1.8 mm.  Spores 17–22 µm.

Capsules mature in summer.  Common in arctic or alpine tundra, soil, rocks or soil over rocks, rock ledges, cliff shelves, rarely decayed wood and stumps, sometimes in bogs and fens; 30–3700 m; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Colo., Maine, Minn., Mont., N.H., N.Y.; Europe; Asia.

This is an Arctic-alpine species that is easy to recognize because the plants are relatively small, slender, glossy and grow in dense, compact tufts.  The leaves are short, narrow, usually less than 6 ´ 0.5 mm, ending in a long, fine, tubulose subula, acute at the apex, smooth or nearly so on the abaxial surface, and have entire margins or rarely some denticulations at the apex.  Capsules, which are not uncommon on plants in some Arctic localities, are short, less than 2 mm, straight and erect to slightly arcuate, smooth but striate when dry.

Dicranum elongatum can readily be confused with a closely related species D. groenlandicum.  They both are Arctic-alpine species sharing nearly the same type of habitat with almost the same distribution.  They can usually be readily distinguished in their typical form but there appear to be many intergradations that cause difficulty.  Dicranum groenlandicum has narrowly obtuse leaf apices and cells that are pitted to well above the middle of the leaf in contrast to the acute leaf apices and cells that are pitted only up to the middle of the leaf in D. elongatum.  E. Hegewald (1972) found that the pits in the leaf are the most reliable means of separating difficult specimens of Finnish plants.  H. A. Crum and L. E. Anderson (1981) have expressed doubt as to whether the two are genetically different.  Both D. elongatum and D. groenlandicum often bear at the apex of some stems julaceous shoots with small, ovate, broad leaves with obtuse apices.  This can lead to the misidentification of some plants of D. elongatum unless the leaves in the basal part of the stems are always used to determine the shape of the leaf apices.

20.   Dicranum groenlandicum   Bridel, Mant. Musc. 4: 68.  1819

Plants in dense tufts, light green, glossy.  Stems 4.5–10 cm, tomentose throughout with brown to red rhizoids.  Leaves erect-spreading, erect-appressed when dry, smooth, (2.5–)3–4(–6.5) × 0.3–0.5 mm, from an ovate-lanceolate base to a tubulose subula, narrowly obtuse at apex, rarely acute, sometimes apical leaves of stems julaceous, margins entire; laminae 1-stratose, occasional 2-stratose regions near costa in proximal part of leaf; costa subpercurrent to percurrent, 1/10–1/6 width of leaves at base, smooth, abaxial ridges lacking, with a row of guide cells, 2 well-developed and thick stereid bands (5–6 cells thick), adaxial epidermal layer of cells not differentiated, abaxial layer usually with a few cells enlarged; cell walls between lamina cells slightly bulging; leaf cells smooth; alar cells 1- or 2-stratose, well-differentiated, not extending to costa; proximal laminal cells elongate-sinuose, strongly pitted, (36–)54–65(–98) × (2–)5–6(–9) µm; distal laminal cells (11–)17–26(–42) × (2–)5–6(–12) µm.  Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly short-acuminate, convolute-sheathing.  Seta solitary, yellow to reddish yellow, 1.5–2 cm.  Capsule nearly straight and erect to slightly arcuate, yellowish brown, 1.5–2 mm, ± striate when dry; operculum 1–1.7 mm.  Spores 14–19 µm.

Capsules mature in summer.  Arctic or alpine tundra, soil, humus or rocks, sometimes in bogs and fens; 10–3800 m; Greenland; Alta., B.C., Man. Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo., N.Y.; Europe; Asia.

This Arctic-alpine species is sometimes not a very distinct species, often being difficult to separate from its nearest relative, D. elongatum. For distinctions see the discussion under that species.

21.   Dicranum fragilifolium   Lindberg, Bot. Not. 1857: 146.  1857

Plants in compact tufts, light green to yellowish brown, glossy.  Stems 1.5–6 cm, densely tomentose with dark brown to red rhizoids.  Leaves straight, erect-spreading, rigid, appressed when dry, smooth, (5–)6–7(–7.5) × 0.4–0.6 mm, most of the leaf tips deciduous and lacking, concave below, canaliculate above, from a lanceolate base to a long subula formed by excurrent costa, apex acute, margins entire to somewhat serrulate above; laminae 1-stratose or some 2-stratose regions near costa; costa excurrent, 1/4–1/3 width of leaves at base, smooth or slightly rough above on abaxial surface, abaxial ridges lacking, with a row of guide cells, 2 thin stereid bands (2–3 cells thick), adaxial and abaxial epidermal layers not differentiated or sometimes with a few cells in both layers enlarged; cell walls between lamina cells slightly bulging; leaf cells smooth; alar cells 1-stratose, sometimes with some 2-stratose regions, well differentiated, sometimes extending to costa; proximal laminal cells elongate-rectangular, usually pitted or indistinctly pitted, (25–)39–55(–84) × (5–)7–8(–10) µm; median laminal cells rectangular, not pitted, (11–)21–22(–37) × (4–)7–8(–10) µm; distal laminal cells nearly elliptic, incrassate.  Sexual condition dioicous; male plants as tall as females, usually more slender; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta solitary, yellowish to brown, 1.5–2.5 cm.  Capsule arcuate to nearly straight, ± erect, yellowish brown, 1.8–2 mm, smooth, sometimes striate when dry; operculum 1–2 mm.  Spores 16–28 µm.

Capsules mature in summer.  Rotten logs and stumps, humic soil, humus over rocks, usually in coniferous woods, occasionally in mixed woods and bogs; 30–1900 m; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., Ont., Que., Sask.,Yukon; Alaska, Mich.; Europe; Asia.

This is a rare boreal species with shiny, light green to yellowish brown, erect-spreading leaves.  The distal portion of the leaves is fragile and often broken off, thereby giving the plants a distinctive appearance.  The deciduous leaf apices presumably serve as a type of asexual reproduction by regenerating to produce new plants.  The species is often confused with D. tauricum, another species with deciduous leaf tips, but D. tauricum occurs only in western North America. Where their ranges overlap they frequently are difficult to tell apart.  When sporophytes are present the straight capsules of D. tauricum are distinctive from the usually arcuate ones of D. fragilifolium, which unfortunately rarely produces them.  When sterile, the best way to separate the two is by the costa cross section in the proximal half of the leaf:  Dicranum fragilifolium has stereid cells in two thin bands while D. tauricum has none.  Also, in Dicranum fragilifolium there are 2–3 layers of cells above and below the guide cells, while in D. tauricum there are 1 or rarely 2 layers of cells.  One other species with deciduous leaf tips that has sometimes been confused with D. fragilifolium is D. viride of eastern North America.  It has a straight capsule like D. tauricum but as in D. fragilifolium capsules are rarely produced.  The broad costa of D. viride, covering one third or more of the leaf base, will distinguish it from D. fragilifolium, the costa of which covers one fourth or less of the leaf base.

22.   Dicranum fulvum   Hooker, Musci Exot. 2: 149.  1819

Plants in loose tufts, dark green above, blackish green below, dull.  Stems 1.5–3.5 cm, sparsely tomentose with light- to reddish-brown rhizoids.  Leaves erect-spreading, some weakly falcate-secund, crisped when dry, smooth, (3–)4–5(–7) × 0.5–0.8 mm, some leaf tips broken off, concave below, subtubulose above, narrowly lanceolate to a long, narrow subula occupied mainly by the excurrent costa, apex acute, margins serrate to serrulate in distal 1/2; laminae 1- or 2-stratose above, sometimes 2-stratose in patches; costa excurrent, 1/4–1/3 width of leaves at base, abaxially toothed or papillose in distal 1/2, abaxial ridges lacking, with a row of guide cells, 2 stereid bands not extending above leaf middle, adaxial and abaxial epidermal layers of cells somewhat differentiated or with a few cells enlarged in both layers, cell walls between lamina cells strongly bulging in distal part of leaf lamina; leaf cells smooth or abaxially prorate above; alar cells mostly 1-stratose or sometimes with a few 2-stratose cells, distinctly differentiated, often extending to costa; proximal laminal cells elongate-rectangular, not pitted or with few pits, (19–)24–33(–42) × (4–)5–6(–9) µm; distal laminal cells regularly quadrate to short-rectangular, not pitted, (5–)10–11(–16) × (4)5–6(9) µm.  Sexual condition dioicous; male plants as tall as female plants but usually more slender; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta solitary, brown or reddish brown, 1–2 cm.  Capsule straight and erect, reddish brown, 1.5–3 mm, smooth, slightly furrowed when dry; operculum 1.5–2 mm.  Spores 14–28 µm.

Capsules mature in spring.  Sandstone, limestone or acidic rock outcrops, bluffs, cliff faces, and boulders in deciduous woodlands, especially along streams; rarely on bases of tree trunks, fallen trees and logs; 200–1900 m; N.B., N.S., Ont., Que.; Ala, Ark., Conn., D.C., Ga., Ill., Ind., Iowa , Ky., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.; Europe; Asia.

This eastern North American species, occurring primarily on rock, has dull, blackish green plants, especially evident from the leaves on the basal part of the stems, crisped leaves when dry, broad costae that cover 1/4–1/3 the width of the leaves at base, laminae that are mostly 2-stratose in the distal half of the leaf, and erect, cylindrical capsules that are slightly furrowed when dry.  The species is sometimes confused with Dicranum fuscescens but that species has keeled leaves in the distal half, with 2-stratose regions restricted to the margins, and horizontal capsules, whereas D. fulvum has subtubulose leaves, with almost entirely 2-stratose laminae above, and erect capsules.  When D. fulvum has some of its leaf apices broken off, which is not uncommon, it can be confused with D. viride, which has the majority of its leaf tips lacking.  The usual occurrence on rock of plants of D. fulvum as opposed to the usual occurrence on bases of tree trunks of D. viride often gives some clue to their identity. Morphologically, the proximal leaf cells of the two differ:  D. fulvum has shorter cells, averaging 24–33 µm, compared to the longer cells of D. viride, averaging 33–42 µm.

23.   Dicranum viride   (Sullivant & Lesquereux) Lindberg, Hedwigia 2: 70.  1863

Campylopus viridis Sullivant & Lesquereux, Musc. Bor. Amer. 18. 1856; Dicranum fulvum subsp. viride (Sullivant & Lesquereux) Lindberg; D fulvum var. viride (Sullivant & Lesquereux) Frye

Plants in loose to dense tufts, yellowish to dark green, glossy to dull.  Stems 1.5–4.5 cm, sparsely tomentose with whitish to reddish brown rhizoids.  Leaves erect-spreading or somewhat falcate-secund, rigid, erect below and flexuose above when dry, smooth, (3–)4–6(–7) × 0.5–0.8 mm, most of the leaf tips broken off, concave below to canaliculate above, from a lanceolate base to a long-acuminate, acute apex (when present), margins entire, sometimes slightly denticulate at apex; laminae 1-stratose or with some 2-stratose regions in patches between margin and costa; costa excurrent, 1/5–1/4 width of leaves at base, smooth or slightly rough on abaxial surface in distal 1/2, abaxial ridges lacking, with a row of guide cells, 2 weakly developed stereid bands above and below, not extending above leaf middle, adaxial and abaxial epidermal layers of cells not differentiated or with a few cells enlarged in both layers; cell walls between lamina cells not or weakly bulging; leaf cells usually smooth; alar cells 1-stratose or with a few 2-stratose regions, well-differentiated, often extending to costa; proximal laminal cells rectangular to short-rectangular, not pitted or with few pits, (11–)33–42(–51) × (7–)9–10(–13) µm; median laminal cells regularly quadrate, not pitted, (9–)15–22(–26) × (5–)7–8(–11) µm; distal laminal cells small, quadrate, not pitted.  Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta solitary, yellow to reddish brown, 1–1.6 cm.  Capsule straight, erect, brown to reddish brown, 1.5–2.5 mm, smooth, slightly furrowed when dry; operculum 1–1.5 mm.  Spores 9–22 µm.

Capsules mature in spring. ommonly growing on the base of trees (usually deciduous but sometimes coniferous, especially Thuja), rotten logs, stumps, rarely soil and acidic or limestone rocks; 40–1400 m; N.B., N.S., Ont., P.E.I., Que.; Alaska, Ill., Ind., Iowa, Ky., Maine , Md., Mass., Mich., Minn., N.H., N.Y., N.C., Ohio, Pa., Tenn., Vt., Va., W.Va., Wis.; Europe; Asia.

This is not an uncommon species of the eastern United States and southeastern Canada. It rarely produces sporophytes and is a distinctive species because of the fragile, deciduous leaf tips, which probably serve as a means of asexual reproduction.  It has on occasion been confused with Dicranum fulvum, which has nearly the same distribution, and rarely with D. fragilifolium where their ranges overlap in the Great Lakes region.  For distinctions see the discussion under those species.

The Alaska record is from I. A. Worley and Z. Iwatuski (1970), and the Kentucky record is from Smider et al. (1988).

24.   Dicranum tauricum   Sapjegin, Bot. Jahrb. 46 (Beibl. 105): 10.  1911

Dicranum strictum D. Mohr

Plants in dense tufts, light green to yellowish green, glossy.  Stems 0.5–3 cm, tomentose below with whitish or reddish brown rhizoids.  Leaves straight, erect-spreading, little changed when dry, smooth, 4–6 × 0.2–0.4 mm, most of the leaf tips deciduous and lacking, lanceolate, concave below, tubulose above, apex acute, margins entire or serrulate at apex; laminae 1-stratose or with 2-stratose regions near apex; costa long-excurrent, 1/6–1/4 width of leaves at base, abaxial ridges lacking; leaf cells smooth, guide cells, no stereid bands, 1 or 2 rows of cells above and below guide cells with slightly thickened walls and large lumens, the adaxial and abaxial epidermal layers of cells not differentiated; cell walls between lamina cells not bulging; alar cells 1-stratose, differentiated, not extending to costa; proximal laminal cells rectangular to linear, with a few pits, (46–)60–105(–120) × (4–)6–16(–22) µm; distal laminal cells quadrate, rounded or short-rectangular, not pitted, (12–)17–25(–32) × (8–)10–11(–12) µm.  Sexual condition dioicous; male plants as large as females; interior perichaetial leaves gradually narrowed to a subulate apex, convolute-sheathing.  Seta solitary, yellow to light brown, 1.5–2.5 cm.  Capsule straight and erect, yellow to light brown, 1.4–2.5 mm, smooth, often irregularly wrinkled when dry; operculum 1–1.8 mm.  Spores 10–18 µm.

Capsules mature in summer.  Frequently on rotten logs, stumps, or tree bases in woodlands, sometimes on humus or humus over rocks; 100–2200 m; Alta., B.C., N.W.T., Sask.; Alaska, Calif., Colo., Idaho, Mont., nw Nebr., Oreg., S.Dak., Utah, Wash., Wyo.; Europe.

Dicranum tauricum is a western North American species, occurring primarily on trees and rotten wood. It is recognized as glossy plants with broken off leaf tips and straight, erect capsules.  It can be confused with D. fragilifolium which also has broken off leaf tips and whose range overlaps with D. tauricum. For distinctions see discussion under D. fragilifolium.

The Utah record is from S. Flowers (1973).

25.   Dicranum montanum   Hedwig, Spec. Musc. 143.  1801

Plants in dense tufts, usually with weak, clustered branchlets near stem apices with small, linear, erect-spreading, costate leaves, strongly crisped when dry, yellowish green to dark green, dull,.  Stems 0.5–3(–5) cm, densely tomentose with white to reddish brown rhizoids.  Leaves erect-spreading, cirrate to strongly crisped when dry, smooth, (1–)2–3(–4) × 0.2–0.5 mm, concave below, subtubulose to keeled above, lanceolate at base, acuminate above to an acute apex, rough above on abaxial surface, margins irregularly serrate to serrulate in distal 1/2 of leaves; laminae 1-stratose; costa percurrent to shortly excurrent, 1/6–1/4 width of leaves at base, rough with papillae or teeth on abaxial surface in distal 1/2 of leaf, abaxial ridges lacking, with a row of guide cells, 2 weakly developed stereid bands above and below, not extending to leaf middle, adaxial and abaxial epidermal layers of cells not differentiated or with a few cells enlarged in both layers; cell walls between lamina cells not bulging; leaf cells smooth below, mammillose or usually abaxially prorate or toothed in distal 1/2 of leaves, giving leaves a dull appearance; alar cells 1-stratose, differentiated or sometimes indistinctly differentiated, not extending to costa; proximal laminal cells rectangular to oblong-rectangular, not pitted or with few pits, (10–)20–32(–50) × (4–)6–8(–13) µm; distal laminal cells usually quadrate to short-rectangular, some cells transversely elongate, not pitted, (5–)8–10(–26) × (2)3–6(9) µm.  Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly acuminate, convolute-sheathing.  Seta solitary, rarely 2 per perichaetium, yellowish to reddish brown, 0.5–1.5 cm.  Capsule straight and erect to slightly inclined, rarely somewhat arcuate, light yellowish brown, 1.2–2 mm, smooth, striate when dry; operculum 1–1.5 mm.  Spores 12–24 µm.

Capsules mature in spring.  Rotting stumps and logs, tree bases (usually deciduous trees), occasionally soil or humus over rocks, especially boulders and cliff ledges, in dry to mesic woods, rarely swamps; 0–2800 m; B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask.; Alaska, Ariz, Ark., D.C., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mo., Nebr., N.H., N.Mex., N.Y., N.C., Ohio, Okla., Pa., Tenn., Vt., Va., W.Va., Wis.; Europe; Asia.

This is one of the smallest species of the genus in North America.  It can best be recognized by the small plants, often only 1–2 cm, the dull, yellowish green to dark green leaves that are strongly crisped when dry, the lanceolate, acuminate leaves that are subtubulose to keeled above, rough on the abaxial surface near the apex, and the straight, erect capsules.  Also aiding in its recognition are the occasional presence of small, delicate, clustered branchlets with linear leaves that are readily detachable (probably a means of asexual reproduction), which occur near the stem apices.  The detached leaves from the branchlets leave characteristic scars on the denuded portions.  Dicranum montanum can sometimes be mistaken for D. flagellare, its closest relative, especially when the latter species does not have its typical flagelliform branchlets in the leaf axils or when they have been overlooked.

Dicranum montanum has leaves with a keeled subula in the distal half, with a strongly papillose or toothed abaxial surface near the apex and distal leaf cells that are regularly quadrate. Dicranum flagellare, in contrast, has leaves with a tubulose subula above, with the abaxial surface usually smooth, and mostly short-rectangular leaf cells.

26.   Dicranum flagellare   Hedwig, Spec. Musc. 130.  1801

Dicranum flagellare var. minutissimum Grout

Plants in dense tufts, usually bearing 2–6 dark green, stout, terete branchlets, 1–4 mm, in the axils of distal leaves, each flagelliform branchlet with short, ovate to lingulate, broadly acute to obtuse, ecostate or shortly and indistinctly costate leaves closely appressed to the axis, yellowish green to dark green, glossy.  Stems 0.5–6 cm, densely tomentose with light brown to reddish brown rhizoids.  Leaves falcate-secund to nearly straight, crisped to weakly crisped when dry, smooth, (1–)2–4(–5) × 0.3–0.6 mm, concave below, tubulose above, from a lanceolate or ovate-lanceolate base to an acuminate subula, apex acute, margins smooth to serrulate above; laminae 1-stratose; costa percurrent or sometimes ending just before apex, 1/6–1/4 width of leaves at base, smooth to ± rough with papillae or small teeth on abaxial surface near apex of leaf, abaxial ridges lacking, with a row of guide cells, 2 stereid bands above and below not extending above leaf middle, adaxial epidermal layer of cells not differentiated, abaxial layer with some cells differentiated; cell walls between lamina cells not bulging; leaf cells smooth or weakly abaxially prorate above; alar cells 1-stratose, distinctly differentiated, not extending to costa; proximal laminal cells elongate-rectangular, not pitted or with few pits, (12–)24–38(–70) × (4–)10–15(–18) µm; distal laminal cells short-rectangular to quadrate, not pitted, (5–)12–14(–23) × (5–)7–12(–14) µm.  Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing.  Seta solitary, yellowish to brown, 1–2.5 cm.  Capsule straight and erect or nearly so, yellowish brown to brown, 1.5–3 mm, striate when dry; operculum 0.5–l.6 mm.  Spores 12–19 µm.

Capsules mature in spring.  Rotting wood, especially stumps and logs, base of trees, exposed tree roots, soil or humus over boulders usually in mesic woods, sometimes swamps and bogs; 0–1300 m; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask.; Ala., Ariz., Ark., Colo., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Vt., Va., W.Va., Wis.; Mexico (Chihuahua, Coahuila, Durango, Jalisco, Nuevo León, Tamaulipas); West Indies; Central America (Costa Rica, Guatemala, Panama); Europe; Asia.

Dicranum flagellare is easily recognized because of the presence of unique axillary, flagelliform branchlets, in clusters of 2–6, which almost always some plants in each colony possess.  The branchlets are deciduous and represent another type of asexual reproduction present in species of Dicranum, e.g., deciduous branchlets with linear, crisped leaves in D. montanum, and deciduous leaf tips in D. fragilifolium, D. tauricum and D. viride.  C. Correns (1899) discusses the flagelliform branchlet type of asexual reproductive in D. flagellare as well as the other types of asexual reproduction occurring in the genus.  The only species likely to be confused with D. flagellare if the flagelliform branchlets are overlooked or cannot be found is D. montanum.  For distinctions see the discussion under that species.

The Northwest Territory record is from W. Peterson (1979), and the Arizona record is from I. M. Haring (1961).

 

Excluded species:

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).