Greek dicranon, pitchfork

Robert R. Ireland

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

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

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

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

EXCLUDED TAXA

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).

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.

OTHER REFERENCES

Briggs, D. 1965. Experimental taxonomy of some British species of the genus Dicranum. New Phytol. 64: 366--386.
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Eversman, S. and A.J. Sharp. 1980. First checklist of Montana mosses. Proc. Montana Acad. Sci. 39: 12--24.
Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University Press, Provo.
Haring, I.M. 1961. A checklist of the mosses of the state of Arizona. The Bryologist 64 (2--3):222--240.
Hegewald, E. 1972. Dicranum groenlandicum in Finland. Memo. Soc. Fauna Flora Fenn. 48: 85--87.
Hilferty, F.J. 1960. The mosses of Massachusetts. A county catalogue with annotations. Rhodora 62: 145--173.
Holzinger, J.M. 1925. Dr. Brotherus’ treatment of Dicranum. The Bryologist 28: 22.
Ireland, R.R. 1966 (1965). Dicranum pallidisetum in western North America. The Bryologist 68(4): 446--450.
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Mönkemeyer, W. 1927. Die Laubmoose Europas, Andreaeales-Bryales. In L. Rabenhorst, Kryptogamen-Flora von Deutschland, Österreich und der Schweiz. Vol. 4. Leipzig.
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Podpêra, J. 1954. Conspectus muscorum Europaeorum. Czechoslovakia Academy, Prague.
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Sérgio, C., R. Ochyra and A. Séneca. 1995. Dicranum crassifolium (Musci, Dicranaceae), a new species from southern Europe. Fragm. Flor. Geobot. 40(1): 203--214.
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Snider, J.A. & B.K. Andreas. 1996. A catalogue and atlas of the mosses of Ohio. Ohio Biological Survey, Misc. Contr. No. 2. Ohio State University, Columbus.
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Worley, I.A. and Z. Iwatsuki. 1970. A checklist of the mosses of Alaska. Bryologist 73(1): 59--71.