Dicranum flagellare
Dicranum bonjeanii
dicranum moss, whip fork moss, whip heron's-bill moss
bonjean's dicranum moss, crisped heron's-bill moss
0.5–6 cm, densely tomentose with light brown to reddish brown rhizoids.
2–8 cm, scarcely tomentose with whitish to reddish brown rhizoids.
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 the width of the leaves at base, smooth to ± rough with papillae or small teeth on abaxial surface near apex of leaf, abaxial ridges absent, with a row of guide cells, two stereid bands above and below not extending above the leaf middle, adaxial epidermal layer of cells not differentiated, the 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.
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 the distal half;
laminae 1-stratose;
costa ending just before the apex, sometimes with two poorly developed toothed ridges above on abaxial surface, 1/13–1/8 the width of the leaves at base, row of guide cells, two thin stereid bands, adaxial epidermal layer of cells not differentiated, the abaxial layer with a few (usually 2) cells differentiated in distal part of the 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.
1–2.5 cm, solitary, yellowish to brown.
2.5–3.5 cm, solitary, rarely two per perichaetium, yellowish brown to reddish brown.
1.5–3 mm, straight and erect or nearly so, striate when dry, yellowish brown to brown;
operculum 0.5–l.6 mm.
2.5–3 mm, arcuate, inclined to horizontal, striate when dry, yellow-brown;
operculum 1.7–3 mm.
12–19 µm.
14–28 µm.
Dicranum flagellare
Dicranum bonjeanii
Dicranum flagellare has been reported from Northwest Territories by W. L. Peterson (1979) and Arizona by I. M. Haring (1961). It is easily recognized because of the presence of unique axillary, flagelliform branchlets, in clusters of 2–6, which some plants in each colony almost always 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. E. Correns (1899) discussed 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 25. D. montanum. For distinctions see the discussion under that species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Dicranum bonjeanii was recorded from Maine by B. H. Allen (1998b). It is difficult 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+, fasc. 1) recognize the species as it occurs in Europe, and some that come to North America to collect (e.g., R. K. 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, and thought that they should be kept as separate taxa because each 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.
Dicranum bonjeanii 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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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