Dicranodontium P. Bruch, W. P. Schimper & W. Gümbel, Bryol. Eur. 1: 159. 1847 (fasc. 41 Mon. 1).
Greek dicranon, pitchfork, and odon, tooth
Robert R. Ireland
Plants medium-sized to large, in loose to dense tufts, yellowish brown to dark green. Stems erect, simple or sparingly branched; rhizoids smooth, scattered along stems or present on branch bases. Leaves gradually or abruptly narrowed, tubulose to subtubulose proximally, weakly concave to subtubulose distally, lamina unistratose, acute, erect-flexuose to falcate-secund, occasionally somewhat spreading, sometimes somewhat auriculate at base; margins incurved, serrulate to nearly entire near apex; leaf apex setaceous; costa single, excurrent, broad, filling 1/5--1/2 of leaf base and most of subula, sometimes indistinct, rough distally on abaxial surface, rhizoids at base occasionally on adaxial and commonly on abaxial surfaces, with a median row of guide cells, two stereid bands, epidermal cells differentiated on both surfaces; cells incrassate nearly throughout, distal rectangular to linear, smooth or prorate on abaxial surface, becoming broader toward base, often pitted, alar cells thin-walled, inflated, hyaline or sometimes reddish. Specialized asexual reproduction by deciduous leaves. Sexual condition dioicous. Perigonial leaves broad at base, more abruptly narrowed to a shorter setaceous apex than stem leaves, paraphyses filamentous, antheridia few. Perichaetial leaves often with broader and longer bases more abruptly narrowed distally than stem leaves, paraphyses lacking, archegonia few. Seta solitary, smooth, elongate, curved to cygneous, erect-sinuous when dry. Capsule erect and symmetric, oblong-cylindric, smooth; annulus and stomata lacking; operculum long-rostrate; peristome single, teeth 16, inserted below mouth, divided nearly to base, vertically striolate nearly to tips. Calyptra cucullate, smooth, entire at base, naked. Spores spherical, smooth.
Species 7 (3 in the flora): terrestrial habitats in temperate to tropical regions North, Central and South America, Europe, Asia, Africa, Australia.
This is a small genus of only seven species in the world (J. P. Frahm 1997), three of which occur in North America. Dicranodontium can be confused with Campylopus but difffers primarily in two features: (1) the rhizoids, in addition to being on both surfaces of the costa in the two genera, are scattered along the stems or present at branch bases in Dicranodontium while they are only at the branch bases and branch primordia in Campylopus; and (2) Campylopus usually has ridges or low lamellae on the abaxial surface of the costa near the leaf middle while the costa in the mid-leaf region of Dicranodontium is smooth. Dicranodontium rarely produces perichaetia and perigonia so sporophytes are extremely rare in North America.
EXCLUDED SPECIES
Dicranodontium subporodictyon V.F. Brotherus, known in North America only from British Columbia, has recently been transferred to the genus Campylopus by B. H. Allen and R. R. Ireland (unpubl. ms.). The costa of D. subporodictyon has ridges or small lamellae on the abaxial surface of its costa, as well as a number of other morphological features characteristic of species of Campylopus.
SELECTED REFERENCES
Frahm, J.-P. 1997. A taxonomic revision of Dicranodontium (Musci). Ann. Bot. Fennici 34: 179--204. Ireland, R. R. 1989. The moss genus Dicranodontium (Dicranaceae) in Canada. Can. J. Bot. 67: 640--649.
OTHER REFERENCES
Crum, H. A. and L. E. Anderson. 1981. Mosses of Eastern North America. Vol. 1. Columbia University Press, New York.
Gangulee, H. C. 1971. Mosses of Eastern India and Adjacent Regions. Fasc. 2. Calcutta.
Gao, C. and T. Cao. 1992. A synopsis of Chinese Dicranum (Dicranaceae, Musci). Bryobrothera 1: 215--220.
Smith, A. J. E. 1978. The Moss Flora of Britain and Ireland. Cambridge University Press, Cambridge.
